WO2013014424A2

WO2013014424A2 - Network monitoring apparatuses and associated methods

Info

Publication number: WO2013014424A2
Application number: PCT/GB2012/051734
Authority: WO
Inventors: Anthony Peyton; John Kelly
Original assignee: Cable Sense Limited
Priority date: 2011-07-25
Filing date: 2012-07-19
Publication date: 2013-01-31
Also published as: GB201212602D0; GB2493259A; GB201112816D0; WO2013014424A3

Abstract

A network monitoring apparatus for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network. The network monitoring apparatus has a coupling unit associated with a first port included In a network channel of the network and a processing apparatus. The coupling unit is configured to receive a signal which has propagated along the network channel between at least two twisted pairs in the network channel. The processing apparatus is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of a signal received by the coupling unit. The processing apparatus may be used to determine whether the network channel is active or inactive, for example.

Description

NETWORK MONITORING APPARATUSES AND ASSOCIATED METHODS

This invention relates to network monitoring apparatuses for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels and/or for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, and associated methods. The determination as to whether two ports are included in the same network channel may be used to identify and/or map interconnections between a plurality of first ports and a plurality of second ports, for example.

Cables which include a plurality of twisted pairs, referred to as "twisted pair cables" herein, are well known. Such cables are commonly used for telecommunications purposes, e.g. computer networking and telephone systems. In the field of telecommunications, twisted pair cables are usually provided without shielding, i.e. as unshielded twisted pair (UTP) cables. However, twisted pair cables containing shielding ("shielded twisted pair cables" herein) are also known.

In this context, a "twisted pair" is a pair of conductors, usually a forward conductor and a return conductor of a single circuit, which have been twisted together. The conductors are usually twisted together for the purposes of cancelling out electromagnetic interference from external sources and to minimise cross-talk between neighbouring twisted pairs within a cable comprising a plurality of twisted pairs. In this way, each twisted pair provides a reliable respective communication channel for a signal, usually a differential voltage signal, to be conveyed within the twisted pair. Common forms of unshielded twisted pair cables are category 5 and category 6 unshielded twisted pairs which include eight conductors twisted together in pairs to form four twisted pairs.

The design and construction of twisted pair cables is carefully controlled by manufacturers to reduce noise due to electromagnetic interference and to reduce cross-talk between the twisted pairs within the cables. To this end, each twisted pair in a twisted pair cable normally has a different twist rate (i.e. number of twists per unit length along the cable) from that of the other twisted pairs in the cable. It is also usual for the twisted pairs to be twisted around each other within the cable. Fillets or spacers may be used to separate physically the twisted pairs.

To further reduce crosstalk between twisted pairs within a cable or to reduce crosstalk between separate cables, which is know as alien channel crosstalk, electromagnetic (or "electric") shielding or screening may be used, which typically is of electrically conductive material, usually metallic foil.

Within this application, the term "shielded twisted pair cable" is to be interpreted as a twisted pair cable that includes electromagnetic shielding, i.e. shielding for inhibiting an electromagnetic field, e.g. of electrically conductive material. The electromagnetic shielding may include electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs, e.g. with each twisted pair surrounded by its own electromagnetic shielding that shields it from the other twisted pairs, e.g. so as to prevent crosstalk between the twisted pairs. The electromagnetic shielding may additionally, or alternatively, include an outer electromagnetic shielding that surrounds all twisted pairs, e.g. so as to reduce/prevent alien channel crosstalk and/or to shield the twisted pairs from external electromagnetic interference (EMI). In order to make the electromagnetic shielding effective, it is usually connected to a ground.

The terminology used to describe shielded twisted pair cables varies from manufacturer to manufacturer. For consistency, a shielded twisted pair cable including electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs but does not include an outer electromagnetic shielding that surrounds all twisted pairs is herein referred to as an "STP" cable (outside of this patent application, such cables can sometimes be referred to as "shielded twisted pair" or "screened twisted pair cables, but this is avoided in the present application where the term "shielded twisted pair" cable is reserved for identifying a twisted pair cable that includes any form of electromagnetic shielding). A shielded twisted pair cable including an outer electromagnetic shielding (e.g. foil) that surrounds all twisted pairs but does not include electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs is herein referred to as a "foil/unshielded twisted pair" or "F/UTP" cable. A twisted pair cable including both electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs and an outer electromagnetic shielding that surrounds all twisted pairs is herein referred to as a "screened fully shielded twisted pair" or "S/FTP" cable (sometimes "S/STP" is also used to describe this type of cable).

Telecommunications networks, e.g. local area networks (LANs), are also well known. Local area networks are typically used to enable equipment such as computers, telephones, printers and the like to communicate with each other and with remote locations via an external service provider. Local area networks typically involve twisted pair network cables, usually in the form of unshielded twisted pair cables, although in some case shielded twisted pair cables such as STP or F/UTP may be employed. The twisted pair cables generally interconnect network ports within the network to form one or more network channels (or "lines") through which data can be communicated.

The network cables in a local area network are typically connected to dedicated service ports throughout one or more buildings. The network cables from the dedicated service ports can extend through the walls, floor and/or ceilings of the building to a communications hub, typically a communications room containing a number of network cabinets. The network cables from wall and floor sockets within the building and from an external service provider are also usually terminated within the communications room.

A "patch system" may be used to interconnect various network channels of the local area network within the network cabinets. In a patch system, all of the network channels can be terminated within the network cabinets in an organized manner. The terminations of the network channels are provided by the structure of the network cabinets, which are typically organised in a rack system. The racks contain "patch panels", which themselves involve sets of network ports, typically RJ45-type or screened RJ45-type connector ports, at which the network channels terminate.

Each of the network ports in each patch panel is generally wired to one of the local area network's network channels. Accordingly, each network channel is terminated on a patch panel in an organized manner. In small patch systems, all network channels may terminate on the patch panels of the same rack. In larger patch systems, multiple racks are used, wherein different network channels terminate on different racks.

The interconnections between the various network channels are made using "patch" cables, which are typically shielded or unshielded twisted pair cables including four twisted pairs. Each end of a patch cable is terminated by a connector, such as an RJ-45 type connector for inserting into an RJ- 5 type connector port as described above. One end of the patch cable is connected to the network port of a first network channel and the opposite end of the patch cable is connected to the network port of a second network channel. By selectively connecting the various network channels using the patch cables, a desired combination of network interconnections can be achieved.

Fig. 1 shows a typical patch system organised into a server row, a cross-connect row and a network row, which include four patch panels. Four patch cables are used to interconnect two network channels through the patch system.

In many businesses, employees are assigned their own computer network access number so that the employee can interface with the companies IT infrastructure. When an employee changes office locations, it is not desirable to provide that employee with newly addressed network port. Rather, to preserve consistency in communications, it is preferred that the exchanges of the network ports in the employee's old office be transferred to Ihe telecommunications ports in the employee's new location. This type of move is relatively frequent. Similarly, when new employees arrive and existing employees depart, it is usually necessary for the patch cables in the network cabinet(s) to be rearranged so that each employee's exchanges can be received in the correct location.

As the location of employees change, the patch cables in a typical cabinet are often manually entered in a computer based log. This is burdensome. Further, technicians often neglect to update the log each and every time a change is made. Accordingly, the log is often less than 100% accurate and a technician has no way of reading where each of the patch cables begins and ends. Accordingly, each time a technician needs to change a patch cable, that technician manually traces that patch cable between an internal line and an external line. To perform a manual trace, the technician locates one end of a patch cable. The technician then manually follows the patch cable until he/she finds the opposite end of that patch cable. Once the two ends of the patch cable are located, the patch cable can be positively identified. It takes a significant amount of time for a technician to manually trace a particular patch cable, especially in large patch systems. Furthermore, manual tracing is not completely accurate and a technician may accidently go from one patch cable to another during a manual trace. Such errors result in misconnected patch cables which must be later identified and corrected.

Attempts have been made in the prior art to provide an apparatus which can automatically trace the common ends of each patch cable within local area networks, thereby reducing the labour and inaccuracy of manual tracing procedures.

For example, US Patent Number 5483467 describes a patching panel scanner for automatically providing an indication of the connection pattern of the data ports within a local area network, so as to avoid the manual task of identifying and collecting cable connection information. In one embodiment, which is intended for use with shielded twisted pair cables, the scanner uses inductive couplers which are associated with the data ports. The inductive coupler is disclosed as being operative to impose a signal on the shielding of shielded network cables in order to provide an indication of the connection pattern produced by connection of the cables to a plurality of ports.

In another embodiment of US Patent Number 5483467, the scanner is coupled to each data port by "dry contact" with a dedicated conductor in a patch cable. This is difficult to implement in practice, because most network cables have to meet a particular pre-determined standard in the industry, such as RJ45, in which there is no free conductor which could be used for determining interconnectivity.

US Patent Number 6222908 discloses a patch cable identification and tracing system in which the connectors of each patch cable contain a unique identifier which can be identified by a sensor in the connector ports of a

telecommunications closet. By reading the unique identifier on the connectors of each patch cable, the system can keep track of which patch chords are being added to and removed from the system. Although this system avoids the use of dedicated conductors in the patch cable, it is difficult to implement because it requires use of non-standard patch cables, i.e. patch cables with connectors containing unique identifiers.

International Patent Application Publication Number WO00/60475 discloses a system for monitoring connection patterns of data ports. This system uses a dedicated conductor which is attached to the external surface of a network cable in order to monitor the connection pattern of data ports. Although this allows the system to be used with standard network cables, it still requires the attaching of dedicated conductors to the external surfaces of network cables and adapter jackets which are placed over the standard network cable.

US Patent Number 6285293 discloses another system and method for addressing and tracing patch cables in a dedicated telecommunications system. The system includes a plurality of tracing interface modules that attach to patch panels in a telecommunications closet. On the patch panels, are located a plurality of connector ports that receive the terminated ends of patch cables. The tracing interface modules mount to the patch panels and have a sensor to each connector port which detects whenever a patch cable is connected to the connector port. A computer controller is connected to the sensors and monitors and logs all changes to the patch cable interconnections in an automated fashion. However, this system cannot be retrofitted to an existing network and relies on the operator to work in a particular order if the patch cable connections are to be accurately monitored.

International Patent Application Publication Number WO2005/109015, by the present inventors, which relates to the field of cable state testing, discloses a method of determining the state of a cable comprising at least one electrical conductor and applying a generated test signal to at least one conductor of the cable by a non-electrical coupling transmitter. The reflected signal is then picked up and compared with expected state signal values for the cable, so that the state of the cable can be determined. The inventors have found that signals coupled to a twisted pair cable by the methods described in WO2005/109015 have a tendency to leak out from the twisted pair cable, especially when other twisted pair cables are nearby.

UK patent application GB0905361.2 (published as GB2468925), also by the present inventors, describes an invention which relates to apparatuses and methods for coupling a signal to and/or from a cable which includes a plurality of twisted pairs. In particular, this invention relates to coupling a signal to and/or from such a cable by non-contact (capacitive) coupling with the cable. Such signals may be used to determine interconnections, e.g. within a local area network. The disclosure of GB0905361.2 generally relates to a discovery that a twisted pair cable, e.g. an unshielded twisted pair (UTP) cable, provides communication channels which are additional to the respective communication channel provided within each twisted pair in the cable. In particular, it has been found that additional communication channels exist between each combination of two twisted pairs within a twisted pair cable, due to coupling between the twisted pairs. Each combination of two twisted pairs within a twisted pair cable has been termed a "pair-to-pair" combination. Therefore, the additional communication channels may be termed "pair-to-pair" channels. GB0905361.2 discloses that a signal which propagates along a twisted pair cable between two of the twisted pairs can propagate reliably and over useful distances, without significantly altering the transmission of signals within the individual twisted pairs. Consequently, the "pair-to-pair" signal can propagate in addition to the differential voltage signals which typically propagate within each twisted pair when the twisted pair cable is in use. Therefore test signals can be introduced into the "pair-to-pair" channel and these "pair-to-pair" signals can be used to monitor the operation of the network without disrupting the normal operation of the network.

UK patent application GB1009184.1 , also by the present inventors, discloses signal processing apparatuses and methods for use with a plurality of cable lines (aka "network channels" or "network channels"), such as those including one or more twisted pair cables. In particular, GB1009184.1 relates to apparatuses and methods for analysing one or more characteristics of a test signal coupled out from one of a plurality of cable lines. GB1009184.1 presents apparatuses and methods for analysing a characteristic of a test signal, which may be a "pair-to-pair" signal to determine whether that test signal has propagated directly to the coupling unit via a single cable line or has propagated indirectly to the coupling unit via crosstalk between different cable lines.

UK patent application GB1018582.5 (from which published application WO2012/0S9722 claims priority), also by the present inventors, discloses apparatuses for identifying interconnections in a network comprising a plurality of cable lines and/or for determining the physical state (i.e. condition) of cable lines in the network.

UK patent application GB1106054.8, also by the present inventors and a copy of which is annexed hereto, discloses a coupling unit for use with a twisted pair cable, preferably for use with a shielded twisted pair cable, e.g. of a type widely used in local area networks.

The content of UK patent applications GB0905361.2, GB1009184.1 , GB1018582.5 and GB1106054.8 (and any corresponding published applications, such as WO2012/059722) is incorporated herein by reference.

A limitation of the apparatuses and methods disclosed in UK patent applications GB0905361.2, GB1009184.1 , GB1018582.5, and GB1106054.8 is that these apparatuses and methods, in so far as they relate to determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, generally require a transmitter to send a signal at one port and a receiver to receive that signal at another port, so as to make the determination. This generally requires the transmitter and receiver to be synchronised, which can increase the complexity of the system architecture.

The present invention has been devised in light of the above considerations.

In general, first, second and third aspects of the invention preferably provide a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, wherein a coupling unit couples a reflectometry signal to a network channel that includes a first port and, based at least in part on reflectometry data representative of the reflected reflectometry signal (if it has been reflected), determines whether the first port is included in the same network channel as a second port of the network.

By using reflectometry data in this way, the network monitoring apparatus is able to make a determination as to whether two ports are included in the same network channel based on reflectometry techniques, without the need for a transmitter to send a signal at one port and a receiver to receive that signal at another port. This allows the architecture of a system incorporating the network monitoring apparatus to be simplified.

The determination as to whether two ports are included in the same network channel may be used to identify and/or map interconnections between a plurality of first ports and a plurality of second ports, for example. Herein, to "map" interconnections between a plurality of first ports and a plurality of second ports preferably refers to storing, e.g. in a list, one or more such interconnections.

A first aspect of the invention may provide a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to couple a reflectometry signal to the network channel that includes the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected reflectometry signal from the network channel; and

a processing apparatus configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as a second port of the network, based on an analysis of the reflectometry data.

Herein, the terms "channel", "network channel", "cable line" and "network line" preferably refer to a cable or a plurality of cables connected together by suitable connectors so as to be capable of carrying a signal. These terms may be used interchangeably. Preferably the one or more cables are twisted pair cables. The prefix "twisted pair" may be used with the terms "channel", "network channel", "cable line" and "network line" to indicate the presence of twisted pair cables within the channel.

Herein, the term "port", which may be used interchangeably with "network port", preferably refers to a interface for connecting one element of a network to another, e.g. so as to form a network channel. Such interfaces may conform to a standard, e.g. RJ45, and may be male or female. A connector may include more than one port.

One way in which the processing apparatus could be configured to determine whether the first port is included in the same network channel as the second port, based on an analysis of the reflectometry data, is by having a second coupling unit that is associated with the second port. The processing apparatus can then determine whether the first port is included in the same network channel as the second port based on both first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit and second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit.

Accordingly, the network monitoring apparatus may have:

a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to couple a first reflectometry signal to the network channel that includes the first port and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected first reflectometry signal from the network channel; and

a second coupling unit associated with a second port included in a network channel of the network, wherein the second coupling unit is configured to couple a second reflectometry signal to the network channel that includes the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the second port, to receive the reflected second reflectometry signal from the network channel;

wherein the processing apparatus is configured to produce first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit and second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit and to determine whether the first port is included in the same network channel as the second port, based on an analysis of the first and second reflectometry data. B2012/051734

Preferably, the first coupling unit and second coupling unit are configured to operate independently of each other, preferably such that the operation of one coupling unit is substantially unaffected by the operation of the other coupling unit. This may be achieved e.g. using time domain or frequency domain multiplexing, or a combination of the two. (f there are a plurality of first coupling units and second coupling units (see below), then preferably all of the first coupling units and all of the second coupling units are configured to operate independently of each other, e.g. using time domain or frequency domain multiplexing, or a combination of the two.

The analysis of the first and second reflectometry data by the processing apparatus may include comparing the first and second reflectometry data.

For example, the first and second reflectometry data may be compared using an algorithm involving cross-correlation of the first reflectometry data with the second reflectometry data.

As another example, the analysis of the first and second reflectometry data may include comparing one or more characteristics calculated based on the first reflectometry data with the same one or more characteristics calculated based on the second reflectometry data. The processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the comparison that the one or more characteristics calculated based on the first reflectometry data correspond to the same one or more characteristics calculated based on the second reflectometry data.

The first and second reflectometry data could equally be compared using other techniques/algorithms, as would be appreciated by a person skilled in the art.

Comparing the first and second reflectometry data might be computationally intensive. Accordingly, the analysis by the processing apparatus may include comparing the first and second reflectometry data only if it has been determined that the first and second ports are candidates for being included in the same network channel, e.g. based on whether it is determined that a reflected first reflectometry signal received by the first coupling unit has changed andfar whether it is determined that a reflected second reflectometry signal received by the second coupling unit has changed, e.g. as will now be described.

The analysis of the first and second data by the processing apparatus preferably includes determining if a reflected first reflectometry signal received by the first coupling unit has changed compared with a previous reflected first reflectometry signal received by the first coupling unit and/or determining if a reflected second reflectometry signal received by the second coupling unit has changed compared with a previous reflected second reflectometry signal received by the second coupling unit.

Preferably, the processing apparatus is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that a reflected first reflectometry signal received by the first coupling unit has changed compared with a previous reflected first reflectometry signal received by the first coupling unit and/or whether it is determined that a reflected second reflectometry signal received by the second coupling unit has changed compared with a previous reflected second reflectometry signal received by the second coupling unit.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the first coupling unit has changed at a time that is the same as or corresponds to a time at which a reflected second reflectometry signal received by the second coupling unit has changed. To facilitate this determination, the time at which a reflected first and/or second reflectometry signal has changed may be recorded, e.g. in the first andlor second reflectometry data, e.g. as a time stamp. Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the first coupling unit has changed in a manner that is the same as, or corresponds to, a manner in which a reflected second reflectometry signal received by the second coupling unit has changed. To facilitate this determination, a characteristic associated with the manner in which a reflected first and/or second reflectometry signal has changed may be recorded, e.g. in the first and/or second reflectometry data. The characteristic may, e.g. be an indication that a cable has been connected to or disconnected from a network channel.

Preferably, the network monitoring apparatus has a plurality of the first coupling units and a plurality of the second coupling units, preferably with the processing apparatus being configured to identify and/or map interconnections between the first ports and the second ports, based on an analysis of first and second reflectometry data produced based on reflected first reflectometry signals received by the first coupling units and reflected second reflectometry signals received by the second coupling units.

Accordingly, the network monitoring apparatus is preferably for identifying and/or mapping interconnections between a plurality of first ports and a plurality of second ports in a network that includes a plurality of network channels, the network monitoring apparatus preferably having:

a plurality of the first coupling units, each first coupling unit being associated with a respective first port included in a respective network channel of the network (e.g. with each first coupling unit being configured to couple a respective first reflectometry signal to the respective network channel that includes the respective first port and, if the respective first reflectometry signal is reflected by any one or more discontinuities in the respective network channel, to receive the respective reflected first reflectometry signal from the respective network channel); and

a plurality of the second coupling units, each second coupling unit being associated with a respective second port included in a respective network channel of the network (e.g. with each second coupling unit being configured to couple a respective second reflectometry signal to the respective network channel that includes the respective second port and, if the respective second reflectometry signal is reflected by any one or more discontinuities in the respective network channel, to receive the respective reflected second reflectometry signal from the respective network channel); wherein the processing apparatus is configured to produce first reflectometry data representative of reflected first reflectometry signals received by the first coupling units and second reflectometry data representative of reflected second reflectometry signals received by the second coupling units and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the first and second reflectometry data.

Preferably, the network monitoring apparatus is configured to repeatedly determine whether two ports are included in the same network channel. E.g. the or each first coupling unit may be configured to repeatedly couple a (respective) first reflectometry signal to a (respective) network channel. E.g. the or each second coupling unit may be configured to repeatedly couple a (respective) second reflectometry signal to a (respective) network channel. The processing apparatus may be configured to repeatedly produce first reflectometry data representative of a (respective) reflected first reflectometry signal received by the or each first coupling unit and second reflectometry data representative of a (respective) reflected second reflectometry signal received by the or each second coupling unit and to repeatedly determine whether a first port is included in the same network channel as a second port, based on an analysis of the first and second reflectometry data.

If the network monitoring apparatus for identifying and/or mapping interconnections between the first ports and the second ports in a network that includes a plurality of network channels as described above, then the processing means may be configured to repeatedly update a map of interconnections, based on an analysis of the first and second reflectometry data that includes repeatedly identifying any new interconnections between first ports and second ports and/or repeatedly identifying any lost interconnections between first ports and second ports. The "map" may be a list of interconnections, for example. The network monitoring apparatus may have a modulation unit or a plurality of modulations units, the (or each) modulation unit being configured to modulate a (respective) signal propagating in a (respective) network channel of the network, e.g. so that if a (respective) reflectometry signal is propagating in the (respective) network channel, the (respective) reflectometry signal is modulated by the modulation unit, e.g. so as to contain one or more modulations.

The processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on an analysis of the first and second reflectometry data that preferably involves one or more modulations caused by a modulation unit.

The analysis of the first and second reflectometry data may determining if a reflected first reflectometry signal received by the first coupling unit has changed compared with a previous reflected first reflectometry signal received by the first coupling unit and/or determining if a reflected second reflectometry signal received by the second coupling unit has changed compared with a previous reflected second reflectometry signal received by the second coupling unit, e.g. with the change(s) being one or more modulations caused by a modulation unit. Preferably, the processing apparatus is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that the first and/or second reflectometry signal has changed.

As another example, the analysis of the first and second reflectometry data may include determining whether the first and second reflectometry data include corresponding modulations, e.g. caused by the modulation unit or by some other mechanism, e.g. an operator bending a cable included in the network path. The processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the analysis that the first and second reflectometry data include corresponding modulations.

Instead of using the above described second coupling unit(s), another way in which the processing apparatus could be configured to determine whether the first port is included in the same network channel as the second port, based on an analysis of the reflectometry data, is by having a modulation unit associated with a second port in the network and configured to modulate a signal propagating in the network channel that includes the second port. The processing apparatus can then determine whether the first port is included in the same network channel as the second port based on an analysis of the reflectometry data that preferably involves one or more modulations caused by the modulation unit.

The network monitoring apparatus may have.

a modulation unit associated with a second port included in a network channel of the network, wherein the modulation unit is configured to modulate a signal propagating in the network channel that includes the second port (e.g. so that if a reflectometry signal is propagating in the network channel, the reflectometry signal is modulated by the modulation unit, e.g. so as to contain one or more modulations);

wherein the processing apparatus is configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that preferably involves one or more modulations caused by the modulation unit.

The analysis of the reflectometry data by the processing apparatus preferably includes determining if a reflected reflectometry signal received by the coupling unit has changed compared with a previous reflected reflectometry signal received by the coupling unit, e.g. with the change being one or more modulations caused by the modulation unit.

Preferably, the processing apparatus is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that a reflected reflectometry signal received by the coupling unit has changed compared with a previous reflected reflectometry signal received by the coupling unit, e.g. with the change being one or more modulations caused by the modulation unit.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected reflectometry signal received by the coupling unit has changed at a time that is the same as or corresponds to a time at which the modulation unit was used to modulate a signal propagating in the network channel that includes the second port, e.g. with the change being one or more modulations caused by the modulation unit. To facilitate this determination, the time at which a reflected reflectometry signal has changed may be recorded, e.g. in the reflectometry data, e.g. as a time stamp.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the coupling unit has changed in a manner that is the same as, or corresponds to, a manner in which the modulation unit was used to modulate a signal propagating in the network channel that includes the second port.

TTie processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the analysis that the first and second reflectometry data includes modulations caused by the modulation unit.

Preferably the modulation unit is configured so that the one or more modulations caused by the modulation unit are identifiable as being caused by that modulation unit, so as to allow the processing apparatus to determine whether the reflectometry data includes modulations caused by the modulation unit. For example, this may be achieved by the modulation unit being configured to cause one or more modulations at a pre-determined time, or by being configured to cause one or more modulations that are distinguishable from other features of a reflected reflectometry signal.

Preferably, the network monitoring apparatus has a plurality of the coupling units and a plurality of the modulation units, preferably with the processing apparatus being configured to identify and/or map interconnections between the first ports and the second ports, based on an analysis of reflectometry data produced based on reflected reflectometry signals received by the coupling units.

a plurality of the coupling units, each coupling unit being associated with a respective first port included in a respective network channel of the network (e.g. with each coupling unit being configured to couple a respective reflectometry signal to the respective network channel that includes the respective first port and, if the respective reflectometry signal is reflected by any one or more discontinuities in the respective network channel that includes the respective first port, to receive the respective reflected reflectometry signal from the network channel); and

a plurality of the modulation units, each modulation unit being associated with a respective second port included in a respective network channel of the network (e.g. with each modulation unit being configured to modulate a respective signal propagating in the respective network channel that includes the respective second port, e.g. so that if a reflectometry signal is propagating in the network channel, the reflectometry signal is modulated by the modulation unit, e.g. so as to contain one or more modulations);

wherein the processing apparatus is configured to produce reflectometry data representative of reflected reflectometry signals received by the coupling units and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the reflectometry data (e.g. that preferably involves one or more modulations caused by any one or more of the modulation units). B2012/051734

Preferably, the plurality of modulation units are configured so that the one or more modulations caused by each modulation unit are identifiable as being caused by that modulation unit, so as to allow the processing apparatus to determine whether the reflectometry data includes modulations caused by a particular modulation unit, e.g. so as to allow the processing apparatus to identify and/or map interconnections between the first ports and the second ports based on the reflectometry data. For example, this may be achieved by each modulation unit being configured to cause one or more modulations at a respective pre-determined time e.g. that is different for each modulation unit, or by each modulation unit being configured to cause one or more modulations that are distinguishable from other features of a reflected reflectometry signal and/or the modulations caused by other modulation units.

Preferably, the network monitoring apparatus is configured to repeatedly determine whether two ports are included in the same network channel. E.g. the or each coupling unit may be configured to repeatedly couple a (respective) reflectometry signal to a (respective) network channel. E.g. the or each modulation unit may be configured to modulate a (respective) signal propagating in the (respective) network channel that includes the (respective) second port. The processing apparatus may be configured to repeatedly produce reflectometry data representative of a (respective) reflected reflectometry signal received by the or each coupling unit and to repeatedly determine whether a first port is included in the same network channel as a second port, based on an analysis of the reflectometry data that involves one or more modulations caused by a modulation unit.

If the network monitoring apparatus is for identifying and/or mapping interconnections between the first ports and the second ports in a network that includes a plurality of network channels as described above, then the processing means may be configured to repeatedly update a map of interconnections, based on an analysis of the reflectometry data that includes repeatedly identifying any new interconnections between first ports and second ports and/or repeatedly identifying any lost interconnections between first ports and second ports. The "map" may be a list of interconnections, for example.

One or more network channels described herein may include one or more twisted pair cables including a plurality of twisted pairs, e.g. such that the one or more network channels are twisted pair channels.

One or more signals described herein may be a voltage signal.

One or more reflectometry signals described herein may be suitable for performing time domain and/or frequency domain reflectometry.

One or more first ports described herein may be located in a first patch panel of the network, with one or more aforementioned second ports located in a second patch panel of the network.

One or more coupling units described herein may be configured to couple a reflectometry signal to a network channel such that the reflectometry signal propagates along the network channel between at least two twisted pairs in the network channel, e.g. in the manner described in UK patent application GB0905361.2 or GB1106054.8. Similarly, one or more aforementioned coupling units may be configured to receive a reflected reflectometry signal which has propagated along a network channel between at least two twisted pairs in the network channel, e.g. in the manner described in UK patent application GB0905361.2 or GB1106054.8. Advantageously, this may allow the coupling units to couple reflectometry signals to and receive reflectometry signals from a network channel without disturbing any data signals, e.g. differential voltage signals, propagating within individual twisted pairs in the network channel.

One or more coupling units described herein may be configured to couple a reflectometry signal to/receive a reflected reflectometry signal from a network channel by non-contact coupling with conductors of the network channel, i.e. by coupling that does not require direct electrical ("ohmic") contact with conductors of the network channel. This may be achieved, for example, by capacitive coupling, e.g. in the manner described in UK patent application GB0905361.2 or GB1106054.8. However, it is also possible for one or more aforementioned coupling units to couple a reflectometry signal to/receive a reflected reflectometry signal from a network channel via a direct electrical ("ohmic") connection with conductors of the network channel. One or more coupling units described herein may, for example, be a coupling unit as described in UK patent application GB0905361.2 or GB1106054.8, also by the present inventors. These patent applications each describe coupling units suitable for coupling a reflectometry signal to a network channel by non-contact coupling with twisted pairs of the network channel such that the reflectometry signal propagates along the network channel between at least two twisted pairs in the network channel and suitable for receiving a reflected reflectometry signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with twisted pairs of the network channel.

One or more aforementioned modulation units described herein may be an impedance modulator configured to modulate a signal propagating in a network channel by modulating an impedance of the network channel. However, one or more aforementioned modulation units could be configured to modulate a signal propagating in a network channel by a mechanism other than by modulating an impedance of a network channel, e.g. by adding a modulating signal to the original signal.

One or more modulation units described herein may be configured to modulate a signal propagating in a network channel (e.g. by modulating an impedance of the network channel) based on a control signal, e.g. so that a signal propagating in the network channel can be modulated remotely, e.g. by the processing apparatus.

A network monitoring apparatus described herein may be configured to repeatedly (e.g. at predetermined intervals) determine whether two ports are included in the same network channel or repeatedly identify and/ r map

interconnections between first ports and second ports. This may be achieved, for example, by one or more aforementioned coupling units being configured to repeatedly couple a signal to a network channel and an aforementioned processing apparatus being configured to repeatedly produce aforementioned reflectometry data and repeatedly determine whether two ports are included in the same network channel and/or repeatedly identify and/or map interconnections between first ports and second ports.

A second aspect of the invention may provide a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to couple a first reflectometry signal to the network channel that includes the first port and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected first reflectometry signal from the network channel;

a second coupling unit associated with a second port included in a network channel of the network, wherein the second coupling unit is configured to couple a second reflectometry signal to the network channel that includes the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the second port, to receive the reflected second reflectometry signal from the network channel; and

a processing apparatus configured to produce first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit and second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit and to determine whether the first port is included in the same network channel as the second port, based on an analysis of the first and second reflectometry data.

The network monitoring apparatus according to the second aspect of the invention may have any feature associated with or described in connection with the first aspect of the invention, for example.

A third aspect of the invention may provide a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having: a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to couple a reflectometry signal to the network channel that includes the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected reflectometry signal from the network channel;

a modulation unit associated with a second port included in a network channel of the network, wherein the modulation unit is configured to modulate a signal propagating in the network channel that includes the second port; and a processing apparatus configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that preferably involves one or more modulations caused by the modulation unit.

The network monitoring apparatus according to the third aspect of the invention may have any feature associated with or described in connection with the first aspect of the invention, for example.

Fourth and fifth aspects of the invention relate to a discovery by the present inventors that the presence of data signals within the individual pairs of a network channel can be inferred based on an analysis of a signal received by a coupling unit configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel.

In other words, the inventors have surprisingly found that the presence of data signals propagating within one or more twisted pairs of a network channel can be identified based on an analysis of a "pair-to-pair" signal from the network channel.

A fourth aspect of the invention may provide a network monitoring apparatus for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the network monitoring apparatus having:

a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to receive a signal which has propagated along the network channel between at least two twisted pairs in the network channel; and

a processing apparatus configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of a signal received by the coupling unit.

Thus, by analysing a signal received by a coupling unit configured to receive a "pair-to-pair" signal from the network channel, it can be determined whether one or more data signals are propagating within the individual twisted pairs of the network channel.

A network channel in which one or more data signals are propagating within one or more twisted pairs of the network channel is herein referred to as being "active". Conversely, a network channel in which no data signals are propagating within any twisted pairs of the network channel is herein referred to as being "inactive". Thus, the processing apparatus can be used to determine whether the network channel is active or inactive.

Knowing whether a network channel is active or inactive is information that is particularly useful for network administrators and the like. A particular advantage of this aspect of the invention is that this information can be obtained independently of the systems used to send and receive data signals within the individual twisted pairs of the network channel.

Note here that one or more data signals propagating within one or more twisted pairs of the network channel are not to be confused with a signal which propagates between at least two twisted pairs in the network channel. This is because, as noted above, each twisted pair provides a respective communication channel for a respective signal, usually a differential voltage signal, to be propagated within the twisted pair. A signal which propagates between at least two twisted pairs is different from this because it propagates through an additional ("pair-to-pair") communication channel that involves more than one twisted pair.

Preferably, the processing apparatus is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of a noise floor of a signal received by the coupling unit.

A noise floor of a signal may be defined as a measure of noise contained within the signal. For example, a noise floor of a signal received by the coupling unit may be calculated as the root mean square value of the signal over a predetermined length of time and/or a predetermined frequency range. Preferably the predetermined frequency range includes 13.5MHz-14.5MHz, more preferably 13MHz-15 Hz.

For the avoidance of any doubt, the signal received by the coupling unit need not have been a signal that was coupled to the network channel by a coupling unit configured to couple a signal to a network channel such that the signal propagates along the network channel between at least two twisted pairs in the network channel. For example, the signal received by the coupling unit may be entirely noise (on the pair-to-pair channel).

Indeed, the processing apparatus is preferably configured so that the signal that is analysed by the processing apparatus (to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel) is a signal that is received by the coupling unit between any "pair-to-pair" signals that are coupled to the network channel, as this generally makes it easier to determine the noise floor of the signal.

The inventors have found that the noise floor of a signal received by a coupling unit configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel is indicative of whether one or more data signals are propagating within one or more twisted pairs of the network channel. In particular, the inventors have found that a high noise floor can indicate that one or more data signals are propagating within one or more twisted pairs of the network channel, and that a low noise floor can indicate that no data signals are propagating within any twisted pairs of the network channel.

Preferably, therefore, the processing apparatus is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of whether a noise floor of a signal received by the coupling unit exceeds a predetermined threshold.

For example, the processing apparatus may be configured to determine that one or more data signals are propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the coupling unit exceeds a predetermined threshold.

For example, the processing apparatus may be configured to determine that one or more data signals are not propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the coupling unit is less than (or does not exceed) a predetermined threshold.

The predetermined threshold may depend on a number of factors, and is therefore preferably determined empirically.

Preferably, the coupling unit is configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with conductors of the network channel, e.g. in a manner described in more detail below. In this way, it can be determined whether one or more data signals are propagating within one or more twisted pairs of the network channel in a non-invasive manner.

The network monitoring apparatus may include:

a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to receive a signal which has propagated along the network channel that includes the first port between at least two twisted pairs in the network channel that includes the first port; and

a second coupling unit associated with a second port included in a network channel of the network, wherein the second coupling unit is configured to receive a signal which has propagated along the network channel that includes the second port between at least two twisted pairs in the network channel that includes the second port; and

wherein the processing apparatus is configured to:

determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit based on an analysis of a signal received by the first coupling unit; and

determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit based on an analysis of a signal received by the second coupling unit.

Preferably, the processing apparatus is further configured to determine whether the first port is included in the same network channel as the second port, based on a comparison of one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit with one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit.

In this way, the network monitoring apparatus is able to make a determination as to whether two ports are included in the same network channel without any signals (pair-to-pair signals or otherwise) being added to any network channels by the network monitoring apparatus.

The determination as to whether two ports are included in the same network channel may be used to identify and/or map interconnections between a plurality of first ports and a plurality of second ports, for example.

Preferably, the first and second coupling units are each configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with conductors of the network channel, e.g. in a manner described in more detail below. In this way, it can be determined whether the first port is included in the same network channel as the second port in a non-invasive manner.

A fifth aspect of the invention may provide a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to receive a signal which has propagated along the network channel that includes the first port between at least two twisted pairs in the network channel that includes the first port;

a processing apparatus configured to determine whether the first port is included in the same network channel as the second port, based on a comparison of a signal received by the first coupling unit and a signal received by the second coupling unit.

Preferably, the processing apparatus is configured to determine whether the first port is included in the same network channel as the second port based on an identification of common characteristics of a signal received by the first coupling unit and a signal received by the second coupling unit. These common characteristics could, for example, be one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first and second coupling units.

Accordingly, the processing apparatus could be configured to determine whether the first port is included in the same network channel as the second port, based on a comparison of a signal received by the first coupling unit and a signal received by the second coupling unit in the manner described above with respect to the fourth aspect of the invention, e.g. with the processing apparatus being configured to:

determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit based on an analysis of a signal received by the first coupling unit; determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit based on an analysis of a signal received by the second coupling unit; and determine whether the first port is included in the same network channel as the second port, based on a comparison of one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit with one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit.

However, the processing apparatus may equally be configured to determine whether the first port is included in the same network channel as the second port based on other ways of comparing a signal received by the first coupling unit and a signal received by the second coupling unit.

For example, the processing apparatus may be configured to determine whether the first port is included in the same network channel as the second port based on a cross-correlation of a signal received by the first coupling unit and a signal received by the second coupling unit.

Preferably, one or more coupling units described in connection with the fourth and/or fifth aspects of the invention is configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with conductors of the network channel, i.e. by coupling that does not require direct electrical ("ohmic") contact with conductors of the network channel. This may be achieved, for example, by capacitive coupling, e.g. in the manner described in UK patent application GB0905361.2 or GB1106054.8. For example, one or more coupling units described in connection with the fourth and/or fifth aspects of the invention may, for example, be a coupling unit as described in UK patent application GB0905361.2 or GB1106054.8, also by the present inventors. These patent applications each describe coupling units suitable for receiving a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with twisted pairs of the network channel.

However, it is also possible for one or more aforementioned coupling units to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel via a direct electrical ("ohmic") connection with conductors of the network channel.

A sixth aspect of the invention may provide a kit of parts for forming a monitoring apparatus as described above.

For example, the sixth aspect of the invention may provide.

a kit of parts for forming a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the kit of parts having:

a coupling unit associable with a first port included in a network channel of the network, wherein the coupling unit is configured to couple a reflectometry signal to the network channel that includes the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, toreceive the reflected reflectometry signal from the network channel; and .

The kit of parts may include any feature corresponding to any feature associated with or described in connection with any aforementioned aspect of the invention. For example, the kit of parts may have:

a first coupling unit associable with a first port included in a network channel of the network, wherein the first coupling unit is configured to couple a first reflectometry signal to the network channel that includes the first port and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected first reflectometry signal from the network channel; and

a second coupling unit associable with a second port included in a network channel of the network, wherein the second coupling unit is configured to couple a second reflectometry signal to the network channel that includes the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the second port, to receive the reflected second reflectometry signal from the network channel;

wherein the processing apparatus is configured to produce first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit and second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit and to determine whether the first port is included in the same network channel as the second port, based on an analysis of the first and second reflectometry data.

For example, the kit of parts may have:

a modulation unit associable with a second port included in a network channel of the network, wherein the modulation unit is configured to modulate a signal propagating in the network channel that includes the second port; and wherein the processing apparatus is configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that preferably involves one or more modulations caused by the modulation unit.

For example, the sixth aspect of the invention may provide:

a kit of parts for forming a network monitoring apparatus for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the kit of parts having.

a coupling unit associable with a first port included in a network channel of a network, wherein the coupling unit is configured to receive a signal which has propagated along the network channel between at least two twisted pairs in the network channel; and

For example, the sixth aspect of the invention may provide:

a first coupling unit associable with a first port included in a network channel of a network, wherein the first coupling unit is configured to receive a signal which has propagated along the network channel that includes the first port between at least two twisted pairs in the network channel that includes the first port;

a second coupling unit associable with a second port included in a network channel of the network, wherein the second coupling unit is configured to receive a signal which has propagated along the network channel that includes the second port between at least two twisted pairs in the network channel that includes the second port; and

A seventh aspect of the invention may provide a method corresponding to any other aspect of the invention. For example, there may be provided:

a method of determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the method including:

coupling a reflectometry signal to a network channel that includes a first port using a coupling unit associated with the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, receiving the reflected reflectometry signal from the network channel using the coupling unit; producing reflectometry data representative of a reflected reflectometry signal received by the coupling unit; and determining whether the first port is included in the same network channel as a second port of the network, based on an analysis of the reflectometry data.

The method may include any method step implementing or corresponding to any apparatus feature described in connection with any above aspect of the invention.

For example, the method may include:

coupling a first reflectometry signal to the network channel that includes the first port using a first coupling unit and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, receiving the reflected first reflectometry signal from the network channel using the first coupling unit; and coupling a second reflectometry signal to a network channel that includes the second port using a second coupling unit associated with the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the second port, receiving the reflected second reflectometry signal from the network channel using the second coupling unit;

producing first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit and second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit; and

determining whether the first port is included in the same network channel as the second port, based on an analysis of the first and second reflectometry data.

For example, the method may include:

modulating a signal propagating in a network channel that includes the second port using a modulation unit associated with the second port;

producing reflectometry data representative of a reflected reflectometry signal received by the coupling unit; and determining whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that involves one or more modulations caused by the modulation unit.

For example, the seventh aspect of the invention may provide:

a method of determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the method including:

receiving a signal at a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel; and

determining whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of a signal received by the coupling unit.

For example, the seventh aspect of the invention may provide: a method of determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the method including:

receiving a signal at a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to receive a signal which has propagated along the network channel that includes the first port between at least two twisted pairs in the network channel that includes the first port;

receiving a signal at a second coupling unit associated with a second port included in a network channel of the network, wherein the second coupling unit is configured to receive a signal which has propagated along the network channel that includes the second port between at least two twisted pairs in the network channel that includes the second port; and

determining whether the first port is included in the same network channel as the second port, based on a comparison of a signal received by the first coupling unit and a signal received by the second coupling unit.

There may also be provided a computer-readable medium having computer-executable instructions configured to cause a computer to control a network monitoring apparatus to perform an above described method.

An aforementioned network monitoring apparatus may be configured to, or have means for, implementing any method step described in connection with any above aspect of the invention.

An aforementioned method may include any method step implementing or corresponding to any apparatus feature described in connection with any above aspect of the invention.

The apparatuses and methods described above may be used in conjunction with the apparatuses and methods taught in GB0905361.2, GB1009184.1 , GB1018582.5 and GB1106054.8, also by the present inventors.

The invention also includes any combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

Examples of our proposals are discussed below, with reference to the accompanying drawings in which:

Fig. 1 shows a typical patch system organised into a server row, a cross-connect row and a network row.

Fig. 2. shows an example network channel of a typical network.

Fig. 3 shows a first network monitoring apparatus as applied to the network channel shown in Fig. 2.

Figs. 4a-d shows how the configuration of the network channel shown in Fig. 3 might vary at the network equipment side of a second patch panel.

Figs. 5a-c show how the configuration of the network channel shown in Fig. 3 might vary at the terminal device side of a third patch panel.

Figs. 6a and 6b are plots that respectively show a simulated example of first and second ref!ectometry data produced when first and second coupling units are included in the same network channel.

Fig. 7 shows a simulation model that was used to produce the data shown in Figs. 6a and 6b.

Figs. 8a and 8b are plots that respectively show a simulated example of first and second reflectometry data produced using the simulation model shown in Fig. 7 with the patch cable removed.

Fig. 8c is a plot that shows a simulated example of first reflectometry data produced when the first coupling unit is included in different network channel to that illustrated in Fig. 3.

Fig. 9 shows an example of an algorithm for comparing first and second reflectometry data that involves cross-correlation of the first reflectometry data with the second reflectometry data. Fig. 10 shows an example of an algorithm for mapping interconnections between a plurality of first ports and a plurality of second ports in a network that includes a plurality of network channels.

Fig. 11 shows a modified first network monitoring apparatus which is the same as that shown in Fig. 3, but which has been modified to include a modulation unit configured to modulate a signal propagating in the network channel.

Fig. 12 shows a second network monitoring apparatus as applied to the network channel shown in Fig. 2.

Fig. 13 is a plot that shows an simulated example of first refiectometry data produced if the modulation unit is not modulating signals propagating within a network channel (dotted line) and if the modulation unit is modulating signals propagating in the network channel (solid line).

Figs. 14(a) and (b) are plots that show examples of noise received by a coupling unit configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel.

Fig. 15 shows a third network monitoring apparatus as applied to the network channel shown in Fig. 2.

Fig. 2 shows an example network channel 1 of a typical network, e.g. a local area network, incorporating a patch system.

The network channel 1 shown in Fig. 2 may include a connector 12 of network equipment 10, e.g. a network switch, that is connected to a terminal device connector 72 of a terminal device 70, e.g. a PC, by a series of cables 15, 25, 35, 45, 55, 65, which may be twisted pair cables, and suitable connectors 22, 32, 42, 52, 62, 72, which may be J45 type for example.

For example, the network channel 1 may include: the connector 12 of the network equipment 10, a connector 22 of a first ("connector") patch panel 20 connected to the connector 12 of the network equipment 10 by a first fly lead 15; a connector 32 of a second ("network equipment") patch panel 30 connected to the connector 22 of the first patch panel 20 by a "fixed" (or "permanently installed") lead 25; a connector 42 of a third ("horizontal") patch panel 40 connected to the connector 32 of the second patch panel 30 by a patch cable 35; a connector 52 of a ("horizontal cable") consolidation point 50 connected to the connector 42 of the third patch panel 30 by a "horizontal" cable 45; a connector 62 located in a wall/floor outlet 60 of a building, connected to the connector 52 of the consolidation point 50 by a consolidation point cable 55; and the connector 72 of the terminal device 70 connected to the connector 62 located in the wall/floor outlet 60 of the building by a second fly lead 65.

For the purposes of clarity, Fig. 2 only shows one connector of each of the network equipment 10, first patch panel 20, second patch panel 30, third patch panel 40 and consolidation point 50, whereas these components would typically each include a plurality of such connectors. Also for the purposes of clarity, Fig. 2 only shows one network channel 1 of the network, though it should be appreciated that the network would typically include a plurality of such network channels.

It should be appreciated that Fig. 2 represents only one possible arrangement of a network channel, and that many other arrangements are possible. For example, the first patch panel 20 could be omitted, with the connectors 12 of the network equipment 10 being connected directly to the connectors 32 of the second patch panel 30. Similarly, the consolidation point 50 could be omitted, with the connectors 62 of the wall/floor outlets 60 being directly connected to the connectors 42 of the third patch panel 40.

Fig. 3 shows a first network monitoring apparatus 100 as applied to the network channel 1 shown in Fig. 2.

The first network monitoring apparatus 100 preferably includes a first coupling unit 1 10, a second coupling unit 120 and a processing apparatus. The processing apparatus preferably includes a first refiectometry scanner 130, a second refiectometry scanner 140 and an analysis unit 150, e.g. a computer.

Whilst the first refiectometry scanner 130, second refiectometry scanner 140 and analysis unit 150 of the processing apparatus are shown in Fig. 3 as being separate elements, it should be appreciated that these three elements could be provided as a single unit. The first coupling unit 110 is preferably associated with a first port in the network. The first port may e.g. be an interface included in the connector 32 of the second patch panel 30 and may e.g. be for connecting the connector 32 of the second patch panel 30 to the patch cable 35. Although the first coupling unit 110 is preferably associated with the first port in the network channel 1 , and may e.g. be located adjacent to the first port and/or may be located on the same side of the patch cable 35 as the first port, the first coupling unit 1 0 need not be physically coupled to the first port. For example, Fig. 3 shows the first coupling unit 110 as being physically coupled to the fixed lead 25 that connects the connector 32 of the second patch panel 30 to the connector 22 of the first patch panel 20. Other arrangements are possible, and the first coupling unit 110 need not be physically coupled to any component of the network channel 1 , e.g. if it is configured to couple a signal to the network channel 1 by non-contact coupling, e.g. as described below.

The second coupling unit 120 is preferably associated with a second port in the network. The second port may e.g. be an interface included in the connector 42 of the third patch panel 40 and may e.g. be for connecting the connector 42 of the third patch panel 40 to the patch cable 35. Although the second coupling unit 120 is preferably associated with the second port in the network channel 1 , and may e.g. be located adjacent to the second port, and/or may be located on the same side of the patch cable 35 as the second port, the second coupling unit 120 need not be physically coupled to the second port. For example, Fig. 3 shows the second coupling unit 120 as being physically coupled to the horizontal cable 45 that connects a connector 52 of the consolidation point 50 to the connector 42 of the third patch panel 40. Other arrangements are possible, and the second coupling unit 120 need not be physically coupled to any component of the network channel 1 , e.g. if it is configured to couple a signal to the network channel 1 by non-contact coupling, e.g. as described below.

The first coupling unit 110 is preferably configured to couple a first reflectometry signal to the network channel that includes the first port and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected first reflectometry signal from the network channel.

Similarly, the second coupling unit 120 is preferably configured to couple a second reflectometry signal to the network channel that includes the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel, to receive the reflected second reflectometry signal from the network channel.

In the example shown in Fig. 3, the first and second ports are included in the same network channel 1 , but it should be appreciated that the first and second ports could equally be connected to different network channels including different patch cables 35. This possibility is acknowledged in Fig. 3 by showing the patch cable 35 as a dotted line.

Either/both of the first coupling unit 110 and second coupling unit 120 may be a coupling unit as described in UK patent application GB0905361.2 or GB1 06054.8, also by the present inventors. These patent applications each describe coupling units suitable for coupling a reflectometry signal to a network channel by non-contact coupling with twisted pairs of the network channel such that the reflectometry signal propagates along the network channel between at least two twisted pairs in the network channel and suitable for receiving a reflected reflectometry signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with twisted pairs of the network channel. Advantageously, this may allow the first and/or second coupling units 10, 120 to couple reflectometry signals to and receive reflectometry signals from the network channel 1 without disturbing any data signals, e.g. differential voltage signals, propagating within individual twisted pairs in the network channel 1.

For the avoidance of any doubt, the first coupling unit 110 and/or second coupling unit 120, need not be provided as a single distinct unit contained within a single housing. For example, the first coupling unit 110 and/or second coupling unit 120 may include a separate transmitter unit (not shown) configured to couple a reflectometry signal into a network channel, and a separate receiver unit (not shown) configured to receive a reflectometry signal from a network channel.

The first reflectometry scanner 130 is preferably configured to produce (e.g. repeatedly) a first reflectometry signal to be coupled to the network channel 1 by the first coupling unit 10. The first reflectometry scanner 130 is preferably configured to produce first reflectometry data representative of a reflected first reflectometry signal received by the first coupling unit 110.

Similarly, the second reflectometry scanner 140 is preferably configured to produce (e.g. repeatedly) a second reflectometry signal to be coupled to the network channel 1 by the second coupling unit 120. The second reflectometry scanner 140 is preferably configured to produce second reflectometry data representative of a reflected second reflectometry signal received by the second coupling unit 120.

The first and/or second reflectometry scanners 130, 140 may be configured to produce a reflectometry signal suitable for performing time domain and/or frequency domain reflectometry. For example, the reflectometry signal produced by the first andfor second reflectometry scanners 130, 140 may be a frequency sweep or "broadband" frequency sweep, which may include a sequence of signals each having a different frequencies over a defined range, e.g. a sequence of sine waves signals having different frequencies between 20 MHz and 120 MHz, e.g. at spaced intervals, e.g. of 0.5 MHz. The first and/or second reflectometry scanners 130, 140 may be configured to produce reflectometry data representative of the reflected reflectometry signal in the frequency domain by measuring the intensity of a received reflectometry signal at each frequency in a frequency sweep. Data representative of a reflected reflectometry signal in the frequency domain may be referred to as "frequency domain reflectometry data". An inverse Fourier transform can be used to convert frequency domain reflectometry data into the time domain. Data representative of a reflected reflectometry signal in the time domain may be referred to as "time domain reflectometry data". Of course, this is only an example, and other types of reflectometry signal (e.g. pseudorandom noise), and other measuring techniques could equally be used to produce the reflectometry data, as would be appreciated by a person skilled in the art.

Reflectometry devices capable of producing a reflectometry signal and/or producing data representative of a received reflectometry signal are well known in the art and are sometimes referred to as "reflectometers". One or more such devices may be included in the above-described first and second reflectometry scanners 130, 140.

Preferably, the first and/or second reflectometry scanners 130, 140 shown in Fig. 3 are time domain reflectometry scanners capable of producing time domain reflectometry data.

The analysis unit 150, which may be a computer, is preferably configured to determine whether the first port is included in the same network channel as the second port, based on an analysis of the first and second reflectometry data. An explanation of how the analysis unit 150 may be configured in to make such a determination based on the first and second reflectometry data is explained in more detail below.

Preferably, the first coupling unit 110 and second coupling unit 120 are configured to operate independently of each other, preferably such that the operation of one coupling unit is substantially unaffected by the operation of the other coupling unit. This may be achieved e.g. using time domain or frequency domain multiplexing, or a combination of the t o.

For example, the first coupling unit 110 and second coupling unit 120 may be configured to couple reflectometry signals to/receive reflected reflectometry signals from a network channel simultaneously but using different frequencies (frequency domain multiplexing). For example, the first and second reflectometry signals could be a frequency sweep over the same range of frequencies. Equally, the first and second coupling units 110, 120 could be configured to use different frequencies in that range at different times.

For example, the first coupling unit 110 and second coupling unit 120 may be configured to couple reflectometry signals to/receive reflectometry signals from a network channel at different times (time domain multiplexing). For example, the first coupling unit 1 0 and second coupling unit 120 could be configured to couple reflectometry signals to/receive reflected reflectometry signals from a network channel one at a time, or by interleaving the reflectometry signals.

Figs. 4a-d shows how the configuration of the network channel 1 shown in Fig. 3 might vary at the network equipment side of the second patch panel 30. Fig. 4a shows the same configuration of the network channel 1 as Fig. 3. In use, a first reflectometry signal coupled to the network channel 1 by the first coupling unit 110 will generally result in a reflected first reflectometry signal that contains large reflections from the ends of the network channel 1 , which in this case are at the connector 12 of the network equipment 10 and the connector 72 of the terminal device 70. Smaller reflections, caused by intermediate connectors in the network channel 1 will generally also be present. If the network equipment 10 is transmitting data (e.g. within the twisted pairs of the network channel 1), then the reflected first reflectometry signal will generally also contain a small amount of noise caused by the transmission of this data. This noise is usually apparent on reflectometry data, e.g. TDR plots, produced using the network monitoring apparatus and can provide an indication that the data channel is "live".

Fig. 4b shows the same configuration as Fig. 4a, but with the terminal equipment 10 disconnected or turned off. In this case, the reflected first reflectometry signal will generally not contain noise caused by the transmission of data by the network equipment 10.

Fig. 4c shows the same configuration as Fig. 4a, but with the patch cable 35 disconnected. In this case, the reflected first reflectometry signal will generally contain large reflections from the ends of the network channel 1 , which in this case are at the connector 12 of the network equipment 10 and the connector 32 of the second patch panel 30. Since the length of the network channel 1 is significantly reduced compared to Fig. 4a, the reflected first reflectometry signal will generally contain lots of closely spaced large reflections caused by the first reflectometry signal bouncing back and forth between the ends of the network channel 1.

Fig. 4d shows the same configuration as Fig. 4b, but with the first patch panel 20 omitted such that the network equipment 10 is connected directly to the second patch panel 30, and with the patch cable 35 disconnected from the connector 32 of the second patch panel 30. In this case, the reflected first reflectometry signal will generally contain large reflections from the ends of the network channel 1 , which in this case are at the connector 12 of the network equipment 10 and the connector 32 of the second patch panel 30. Since the length of the network channel 1 is significantly reduced compared to Fig. 4a, the reflected first reflectometry signal will generally contain lots of closely spaced large reflections caused by the first reflectometry signal bouncing back and forth between the ends of the network channel 1. Also, because the first patch panel 20 has been omitted, any smaller reflections caused by the connector 22 of the first patch panel 20 will in general not be contained in the reflected first reflectometry signal.

Figs. 4a-d demonstrate that the reflected first reflectometry signal received by the first coupling unit 110 will in general contain different features depending on the configuration of the network channel 1 at network equipment side of the second patch panel 30. These different features may be unique to the network channel 1 , which may allow the determination of whether the first port is included in the same network channel 1 as the second port, based on an analysis of the first and second reflectometry data.

Of course, Figs. 4a-d only show some of the many possible configurations of the network channel 1 at network equipment side of the second patch panel 30. Other configurations are equally be possible.

Figs. 5a-c show how the configuration of the network channel 1 shown in Fig. 3 might vary at the terminal device side of the third patch panel 40.

Fig. 5a shows the same configuration of the network channel 1 as Fig. 3. In use, a second reflectometry signal coupled to the network channel 1 by the second coupling unit 120 will generally result in a reflected second reflectometry signal that contains large reflections from the ends of the network channel 1 , which in this case are at the connector 12 of the network equipment 10 and the connector 72 of the terminal device 70. Smaller reflections, caused by intermediate connectors in the network channel 1 will generally also be present. If the network equipment 10 is transmitting data, then the reflected second reflectometry signal will generally also contain a small amount of noise caused by the transmission of this data. Fig. 5b shows the same configuration as Fig. 5a, but with the consolidation point 50 omitted such that the connector 62 at the wall/floor outlet 60 is connected directly to the third patch panel 40. In this case, because the consolidation point 50 has been omitted, any smaller reflections caused by the connector 52 of the consolidation point 50 will in general not be contained in the reflected second reflectometry signal.

Fig. 5c shows the same configuration as Fig. 5b, but with the patch cable 35 and second fly lead 65 disconnected. In this case, the reflected second reflectometry signal will generally contain large reflections from the ends of the network channel 1 , which in this case are at the connector 42 of the third patch panel 40 and the connector 62 of the wall/floor outlet 60 of the building. Since the length of the network channel 1 is significantly reduced compared to Fig. 5a, the reflected second reflectometry signal will generally contain lots of closely spaced large reflections caused by the second reflectometry signal bouncing back and forth between the ends of the network channel 1.

Figs. 5a-c demonstrate that the reflected second reflectometry signal received by the second coupling unit 120 will in general contain different features depending on the configuration of the network channel 1 at the terminal device side of the third patch panel 40. These different features may be unique to the network channel 1 , which may allow the determination of whether the first port is included in the same network channel 1 as the second port, based on an analysis of the first and second reflectometry data.

Of course, Figs. 5a-c only show some of the many possible configurations of the network channel 1 at the terminal device side of the third patch panel 40. Other configurations are equally possible.

Figs. 6a and 6b are plots that respectively show a simulated example of first and second reflectometry data produced when the first and second coupling units 110, 120 are included in the same network channel . In both cases, the data is shown in the time domain (as "TDR data" or as a TDR plot"), with signal strength being used as the vertical axis and distance (in metres) being used as the horizontal axis.

Fig. 6a shows various features that provide information about the network channel 1 that includes the first port. For example, a first large reflection X from one end of the network channel 1 (which in this case is the connector 12 of the network equipment 10) and a second large reflection Y from the other end of the network channel 1 (which in this case is the connector 72 of the terminal device 70) can both be seen. Smaller reflections from intermediate connectors included in the network channel 1 can also be seen. The unreflected first reflectometry signal can also be seen at a distance of -0m along the horizontal axis.

Fig. 6b shows various features that provide information about the network channel 1 that includes the second port. For example, a first large reflection A from one end of the network channel 1 (which in this case is the connector 72 of the terminal device 72) and a second large reflection B from the other end of the network channel 1 (which in this case is the connector 12 of the network equipment 10) can both be seen. Smaller reflections from intermediate connectors included in the network channel 1 can also be seen. The unreflected first reflectometry signal can also be seen at a distance of ~0m along the horizontal axis.

Although Figs. 6b generally reflections caused by the same features of the network channel 1 as Figs. 6a, it is important to note that the position of these reflections is different compared with Fig. 6a, because the second coupling unit 120 is at a different location along the network channel 1 from the first coupling unit 110.

As illustrated on Fig. 6a, an estimated length d of a network channel can be calculated, e.g. by the analysis unit 150 of the processing apparatus, based on the first reflectometry data as d = x + y, where x is the distance between the unreflected reflectometry signal and the first large reflection X and y is the distance between the unreflected reflectometry signal and the second large reflection Y. The estimated length d could be calculated, e.g. by the analysis unit 150 of the processing apparatus, based on the second reflectometry data in a similar manner. The processing apparatus may be configured to determine whether the first and second ports are included in the same network channel based, at least in part, on these estimated lengths, e.g. if it is determined as a result of the comparison that these estimated lengths correspond. A skilled person would appreciate that the estimated length d represents only an example of a characteristic that could be calculated based on the first and second reflectometry data, and used to determine whether the first and second ports are included in the same network channel. Other such characteristics would be apparent to a person skilled in the art. For example, an example of another such characteristic is the distance between the first coupling unit 110 and the second coupling unit. For the network channel 1 shown in Fig. 3, this distance could be estimated as x - a, where a is the distance between the unreflected reflectometry signal and the first large reflection in Fig. 6b.

The numbers below the network channel 1 shown in Fig. 7 indicate the reflection coefficients used in the simulation for each of the connectors. The numbers above the network channel 1 shown in Fig. 7 indicate the distances between connectors used in the simulation.

Figs. 8a and 8b are plots that respectively show a simulated example of first and second reflectometry data produced using the simulation model shown in Fig. 7 with the patch cable 35 removed (i.e. unplugged or disconnected). Again, the data is shown in the time domain (as "TDR data" or as a "TDR plot"), with signal strength being used as the vertical axis and distance (in metres) being used as the horizontal axis.

It is evident from comparing Figs. 8a and 8b that the first port associated with the first coupling unit 110 that produced the first reflectometry data shown in Fig. 8a is not included in the same network channel as the second port associated with the second coupling unit 120 that produced the second reflectometry data shown in Fig. 8b.

Fig. 8c is a plot that shows a simulated example of first reflectometry data produced when the first coupling unit 110 is included in different network channel to that illustrated in Fig. 7. Again, the data is shown in the time domain (as "TDR data" or as a "TDR plof ), with signal strength being used as the vertical axis and distance (in metres) being used as the horizontal axis.

The characteristics of Fig. 8c are very different from those of Figs. 6b and 8b. It is evident from comparing Fig. 8c with Fig. 6b and 8b that the first port associated with the first coupling unit 110 that produced the first reflectometry data shown in Fig. 8c is not included in the same network channel as the second port associated with the second coupling unit 120 that produced the second reflectometry data shown in Fig. 6b or Fig. 8b.

The analysis of the first and second reflectometry data by e.g. the analysis unit 150 of the processing apparatus may include comparing the first and second reflectometry data.

Fig. 9 shows an example of an algorithm for comparing first and second reflectometry data that involves cross-correlation of the first reflectometry data with the second reflectometry data.

At the top of Fig. 9, a network channel is shown in which the "PPSW Scanner" acts as the first coupling unit 110 and first reflectometry scanner 130 described above with reference to Fig. 3, and the "PPHZ Scanner" acts as the second coupling unit 120 and second reflectometry scanner 140 as described above with reference to Fig. 3. In the example shown, the PPSW Scanner and the PPHZ Scanner are separated by 3 metres, e.g. by a 3 metre patch cable. The end of the network channel closest to the PPSW Scanner (e.g. a connector 12 of a network switch) is 10 metres from the PPSW Scanner. The end of the network channel closest to the PPHZ Scanner (e.g. a connector 72 of a terminal device 70) is 20 metres from the PPHZ Scanner.

In the middle of Fig. 9, first reflectometry data produced by the PPSW Scanner and second reflectometry data produced by the PPHZ Scanner are illustrated as TDR reflectometry plots. As can be from these plots, if the two scanners are connected to the same network channel, the PPSW Scanner and the PPHZ Scanner independently see the same channel from a slightly different perspective, due to the difference in their location. At the bottom of Fig. 9, the algorithm ("logic") is illustrated, and may be as follows.

After removing any antenna response from the reflectometry ("scan") data, what remains will generally be the "channel response".

1. The first reflection seen by both the PPSW Scanner and the PPHZ scanner is either end of the same interconnecting patch lead. This reflection should be in the same position on each plot if it is the same patch lead.

2. Shifting the plot obtained from the PPHZ Scanner by the distance to the patch lead and taking the inner product of the two signals will show high correlation at the end of the cable attached to the PPSW Scanner.

3. Reversing the process by shifting the plot obtained from the PPSW Scanner by the distance to the patch lead and taking the inner product of the two signals will show a high correlation at the end of the cable attached to the PPHZ Scanner.

As another example, the analysis of the first and second reflectometry data may include comparing one or more characteristics calculated based on the first reflectometry data with the same one or more characteristics calculated based on the second reflectometry data. The processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the comparison that the one or more characteristics calculated based on the first reflectometry data correspond to the same one or more characteristics calculated based on the second reflectometry data. An example of such a characteristic is an estimated length d of a network channel, described above.

Comparing the first and second reflectometry data, e.g. if done using the algorithm described with reference to Fig. 9, might be computationally intensive. Accordingly, the analysis by the processing apparatus may include comparing the first and second reflectometry data only if it has been determined that the first and second ports are candidates for being included in the same network channel, e.g. based on whether it is determined that a reflected first reflectometry signal received by the first coupling unit has changed and/or whether it is determined that a reflected second reflectometry signal received by the second coupling unit has changed, e.g. as will now be described.

The analysis of the first and second data by e.g. the analysis unit 150 of the processing apparatus preferably includes determining if a reflected first reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected first reflectometry signal received by the first coupling unit 110 and/or determining if a reflected second reflectometry signal received by the second coupling unit 120 has changed compared with a previous reflected second reflectometry signal received by the second coupling unit 120.

Preferably, the processing apparatus is configured to determine whether the first port is included in the same network channel as the second port, or are candidates for being included in the same network channel, based on whether it is determined that a reflected first reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected first reflectometry signal received by the first coupling unit 110 and/or whether it is determined that a reflected second reflectometry signal received by the second coupling unit 120 has changed compared with a previous reflected second reflectometry signal received by the second coupling unit 120.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the first coupling unit 110 has changed at a time that is the same as or corresponds to a time at which a reflected second reflectometry signal received by the second coupling unit 120 has changed. To facilitate this determination, the time at which a reflected first and/or second reflectometry signal has changed may be recorded, e.g. in the first and/or second reflectometry data, e.g. as a time stamp. Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the first coupling unit 110 has changed in a manner that is the same as, or corresponds to, a manner in which a reflected second reflectometry signal received by the second coupling unit 120 has changed. To facilitate this determination, a characteristic associated with the manner in which a reflected first and/or second reflectometry signal has changed may be recorded, e.g. in the first and/or second reflectometry data. The characteristic may, e.g. be an indication that a cable has been connected to or disconnected from a network channel. Such an indication may be determined e.g. based on whether an estimated length of a network channel has changed. The estimated length may be calculated as described above with reference to Fig. 6a.

So far, the first network monitoring apparatus 100 has only been described with regard to determining whether a first port is included in the same network channel as a second port. However, these same principles can be extended to provide a network apparatus for identifying and/or mapping interconnections between a plurality of first ports and a plurality of second ports.

Accordingly, the first network monitoring apparatuses 100 may have:

a plurality of the first coupling units 1 10, each first coupling unit being associated with a respective first port included in a respective network channel of the network; and

a plurality of the second coupling units 120, each second coupling unit being associated with a respective second port included in a respective network channel of the network;

wherein the processing apparatus is configured to produce first reflectometry data representative of reflected first reflectometry signals received by the first coupling units 110 and second reflectometry data representative of reflected second reflectometry signals received by the second coupling units 120 and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the first and second reflectometry data.

Preferably, the first network monitoring apparatus 100 is configured to repeatedly determine whether two ports are included in the same network channel. E.g. the or each first coupling unit 110 may be configured to repeatedly couple a (respective) first reflectometry signal to a (respective) network channel. E.g. the or each second coupling unit 120 may be configured to repeatedly couple a (respective) second reflectometry signal to a (respective) network channel. The processing apparatus may be configured to repeatedly produce first reflectometry data representative of a (respective) reflected first reflectometry signal received by the or each first coupling unit 1 10 and second reflectometry data representative of a (respective) reflected second reflectometry signal received by the or each second coupling unit 120 and to repeatedly determine whether a first port is included in the same network channel as a second port, based on an analysis of the first and second reflectometry data.

If the network monitoring apparatus for identifying and/or mapping interconnections between the first ports and the second ports in a network that includes a plurality of network channels as described ataove, then the processing means may be configured to repeatedly update a map of interconnections, based on an analysis of the first and second reflectometry data that includes repeatedly identifying any new interconnections between first ports and second ports and/or repeatedly identifying any lost interconnections between first ports and second ports. The "map" may be a list of interconnections, for example, e.g. the "interconnected cable list" described below.

Fig. 10 shows an example of an algorithm for mapping interconnections between a plurality of first ports and a plurality of second ports in a network that includes a plurality of network channels.

The illustrated algorithm incorporates various analysis techniques that have been described above.

In an initial step S1 , reflectometry is preferably performed (independently) by each of the first and second coupling units 110, 120, which are referred to in Fig. 10 as "transceivers". In step S2, for each first coupling unit 110, it is determined if a reflected first reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected first reflectometry signal received by the first coupling unit 110, and for each second coupling unit 120, it is determined if a reflected second reflectometry signal received by the second coupling unit has changed compared with a previous reflected second reflectometry signal received by the second coupling unit. Any changes are then collated. The time at which a reflected first and/or second reflectometry signal has changed is preferably recorded, e.g. in the first and/Or second reflectometry data, e.g. as a time stamp. A characteristic associated with the manner in which a reflected first and/or second reflectometry signal has changed is preferably recorded as a "change type", which is an indication that a cable has been connected to or disconnected from a network channel. "Change type" may be determined e.g. based on whether an estimated length of a network channel has changed, which may be calculated as described above with reference to Fig. 6a, for example.

In step S3, the collated changes are ordered by a time stamp, which is preferably used to record the time at which a reflected first and/or second reflectometry signal changed as noted above.

In step S4, the collated changes are grouped by change type, change type being an indication that a cable has been connected to or disconnected from a network channel as noted above.

In step S5, it is determined whether there are any changes of the same type that occurred at the same time. If so, the algorithm progresses to step S6. If not, then the algorithm ends.

In step S6, it is determined whether any of the changes (of the same type that occurred at the same time as determined in step S5) are associated with a pair of ports stored in an interconnected cable list. If so, the algorithm proceeds to step S7. If not, the algorithm proceeds to step S9. The interconnected cable list may store pairs of ports that have been determined as being interconnected by a cable (i.e. that have been determined as being included in the same network channel). In this way, the interconnected cable list can be viewed as providing a "map" of interconnections

In step S7, reflectometry data associated with the changes (determined as being associated with a pair of ports stored in the interconnected cable list in step S6), which may be provided in the form of two scans, are compared to determine whether the two scans are compatible, i.e. to determine whether the two scans indicate that the ports associated with those scans are candidates for being included in the same network channel. Preferably, the reflectometry data is compared using the algorithm shown in Fig. 9 and described above, which is referred to as the "Viewpoint" algorithm in Fig. 10. Once the reflectometry data has been compared, the algorithm then proceeds to step S8.

In step S8, if the two scans are determined as being compatible, then the pair of ports stored in the interconnected cable list are confirmed as being interconnected and the algorithm ends. If the two scans are determined as being incompatible, then the pair of ports are removed from the interconnected cable list and the algorithm ends.

In step S9, reflectometry data associated with a pair of changes (of the same type that occurred at the same time as determined in step S5), which may be provided in the form of two scans, are selected for comparison. In step S10, these two scans are then compared to determine whether the two scans are compatible, i.e. to determine whether the two scans indicate that the ports associated with those scans are candidates for being included in the same network channel. Preferably, the reflectometry data is compared using the ("Viewpoint") algorithm shown in Fig. 9 and described above. Once the reflectometry data has been compared, the algorithm then proceeds to step S11.

In step S11, if the two scans are determined as being compatible, then the pair of ports associated with the two scans are added to the interconnected cable list as being interconnected and the algorithm ends. If the two scans are determined as being incompatible, then the pair of ports are not added to the interconnected cable list and the algorithm ends.

The algorithm shown in Fig. 10 is preferably repeated, e.g. at predetermined intervals, so as to repeatedly update the interconnected cable list, e.g. so as to provide "continuous" monitoring of the interconnections between ports. Repeating of the algorithm is referenced in Fig. 10 by the word "continuous". The interconnected cable list described in relation to Fig. 10 effectively provides a map of interconnections between first and second ports in a network, that is repeatedly updated each time the algorithm shown in Fig. 10 is performed.

Of course, the algorithm shown in Fig. 10 is provided as an example, and many other possible algorithms for mapping interconnections between a plurality of first ports and a plurality of second ports in a network that includes a plurality of network channels are equally possible, as would be appreciated by a person skilled in the art.

Although the algorithm shown in Fig. 10 could be used to map interconnections between a plurality of first ports and a plurality of second ports using a network monitoring apparatus configured as shown in Fig. 3, in some cases, the network channels in the network may be so similar that it may be difficult, or take a long time, for the processing apparatus to determine whether first and second ports are included in the same network channel based on changes in the network channels.

For a given network channel, such difficulties can be overcome, for example, by modulating a signal propagating in a network channel of the network, e.g. by modulating an impedance of the network channel, e.g. so as to deliberately cause a change in the channel that can be picked up on by the network monitoring apparatus. If a network channel that includes the first and second network ports is modulated in this way, then the analysis of the first and second reflectometry data may involve one or more modulations so caused. This may include determining whether the first and second reflectometry data include corresponding modulations.

In a simple embodiment, the modulation of a network channel may be caused by an operator bending a cable included in a network channel, e.g. so as to change an impedance of the network channel, so as to allow the processing apparatus to determine whether a first port included in the network channel is included as the same network channel as a second port.

In other embodiments, the first network monitoring apparatus 100 may have a modulation unit 160 or a plurality of modulation units 160, the (or each) modulation unit being configured to modulate a (respective) signal propagating in a (respective) network channel of the network, e.g. so that if a (respective) reflectometry signal is propagating in the (respective) network channel, the (respective) reflectometry signal is modulated by the modulation unit, e.g. so as to contain one or more modulations, e.g. so as to allow or help the processing apparatus to determine whether a first port included in the network channel is included as the same network channel as a second port.

Fig. 11 shows a modified first network monitoring apparatus 100' which is the same as that shown in Fig. 3, but which has been modified to include a modulation unit 160 configured to modulate a signal propagating in the network channel 1.

The modulation unit 160 may be an impedance modulator configured to modulate a signal propagating in a network channel 1 by modulating an impedance of the network channel .

As an example, the (or each) modulation unit 160 may be an inductive device, e.g. a choke, which e.g. can be clipped onto a cable of a network channel 1 , e.g. a patch cable 35, so as to modulate an impedance of the network channel 1. If the first network monitoring apparatus 100' is configured to identify and/or map interconnections between a plurality of first ports and a plurality of second ports in the network (e.g. using the algorithm described in Fig. 1), the choke may be moved from network channel to network channel by an operator, e.g. by clipping it to each of a plurality of patch cables in turn, so as to modulate each of the network channels in turn, so as to allow interconnections between first and second coupling units to be indentified and/or mapped in turn by the processing apparatus. A similar effect could be achieved by the operator bending each patch cable in turn. ^{_ " " "} - -

As another example, the (or each) modulation unit 160 may be a mechanical actuator for applying a mechanical force to a cable of the network channel, so as to alter its impedance.

As another example, the (or each) modulation unit 160 may be a tuned circuit, e.g. a tuned LRC (inductor-resistor- capacitor) circuit. The (or each) modulation unit 160 may be configured to modulate a signal propagating in a network channel (e.g. by modulating an impedance of the network channel) based on a control signal, e.g. so that a signal propagating in the network channel 1 can be modulated remotely, e.g. by the processing apparatus.

If the coupling units are configured to couple signals to a network channel such that the signals propagate between twisted pairs as described above, then the impedance modulator is preferably configured to modulate the impedance between twisted pairs, without significantly altering the impedance within twisted pairs of the network channel. The modulation units described above will generally achieve this.

Fig. 11 shows the modulation unit 160 as being located at the patch cable 35 of the network channel 1. This might be appropriate if the modulation unit 160 is intended to be clipped to and off the network channel 1 by an operator, e.g. as may be the case for the above described inductive device. However, if the modulation unit 160 is configured to modulate an impedance of a network channel based on a control signal, e.g. as may be the case for the above described mechanical actuator and tuned circuit, it may be more appropriate to have the (or each) modulation unit 160 located elsewhere, e.g. in a "fixed" or "permanent" position, e.g. on the horizontal cable 45 as shown in Fig. 12.

The processing apparatus of the modified first network monitoring apparatus 100' may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on an analysis of the first and second reflectometry data that preferably involves one or more modulations caused by a modulation unit 160.

The analysis of the first and second reflectometry data may determining if a reflected first reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected first reflectometry signal received by the first coupling unit 110 and/or determining if a reflected second reflectometry signal received by the second coupling unit 120 has changed compared with a previous reflected second reflectometry signal received by the second coupling unit 120, e.g. with the change(s) being one or more modulations caused by a modulation unit 160. Preferably, the processing apparatus 100' is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that the first and/or second reflectometry signal has changed.

As another example, the analysis of the first and second reflectometry data may include determining whether the first and second reflectometry data include corresponding modulations, e.g. caused by the modulation unit or by some other mechanism, e.g. an operator bending a cable included in the network path. The processing apparatus of the modified first network monitoring apparatus 100' may be configured to determine that the first and second ports 110, 120 are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the analysis that the first and second reflectometry data include corresponding modulations.

An initialisation method could be envisaged to allow the network monitoring apparatus to identify and/or map interconnections between first ports and second ports. Such method could involve the first network monitoring apparatuses repeatedly identifying and/or mapping interconnections between first ports and second ports, e.g. using the algorithm shown in Fig. 10 and described above. The method may also include modulating signals propagating in each network channel, e.g. one at a time, e.g. by an operator bending a cable in each network channel, or using an aforementioned modulation unit 160, so as to create one or more modulations e.g. to be used by the processing apparatus in mapping interconnections in the manner described above. For example, if the network monitoring apparatus determines that corresponding changes or "events" have occurred on reflectometry data produced based on reflectometry signals received by first and second coupling units, that may be used as an indication that the first and second ports associated with those first and second coupling units included in the same network channel.

Fig. 12 shows a second network monitoring apparatus 200 as applied to the network channel 1 shown in Fig. 2. The second network monitoring apparatus 200 has many of the same components as the first network monitoring apparatus 100 shown in Fig. 3 and described above. Alike components have been given alike reference numerals, and need not be described in further detail.

Unlike the first network monitoring apparatus 00 shown in Fig. 3, the second monitoring apparatus preferably has a modulation unit 280 associated with the second port, instead of the second coupling unit 120.

The modulation unit 280 is preferably configured to modulate a signal propagating in the network channel 1 that includes the second port (e.g. so that if a reflectometry signal is propagating in the network channel, the reflectometry signal is modulated by the modulation unit 280, e.g. so as to contain one or more modulations).

Instead of being configured to determine whether the first port is included in the same network channel as the second port based on the first and second data, the analysis unit 250 of the processing apparatus of Fig. 12 is preferably configured to determine whether the first port is included in the same network channel 1 as the second port of the network, based on an analysis of the first reflectometry data that preferably involves one or more modulations caused by the modulation unit 280.

For the avoidance of any doubt, for the second network monitoring apparatus 200, it is not necessary to produce or analyse the second reflectometry data described previously.

The analysis of the reflectometry data by the processing apparatus preferably includes determining if a reflected reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected reflectometry signal received by the first coupling unit 1 0, e.g. with the change being one or more modulations caused by the modulation unit 280.

The processing apparatus is preferably configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that a reflected reflectometry signal received by the first coupling unit 110 has changed compared with a previous reflected reflectometry signal received by the first coupling unit 110, e.g. with the change being one or more modulations caused by the modulation unit 280.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected reflectometry signal received by the first coupling unit 110 has changed at a time that is the same as or corresponds to a time at which the modulation unit 280 was used to modulate a signal propagating in the network channel that includes the second port, e.g. with the change being one or more modulations caused by the modulation unit 280. To facilitate this determination, the time at which a reflected reflectometry signal has changed may be recorded, e.g. in the first reflectometry data, e.g. as a time stamp.

Preferably, the processing apparatus is configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined that a reflected first reflectometry signal received by the first coupling unit 110 has changed in a manner that is the same as, or corresponds to, a manner in which the modulation unit 280 was used to modulate a signal propagating in the network channel that includes the second port.

The analysis unit 250 of the processing apparatus may be configured to determine that the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, if it is determined as a result of the analysis that the first reflectometry data includes modulations caused by the modulation unit.

The modulation unit 280 may, for example, be as described above in relation to the network monitoring apparatus 100' described in relation to Fig. 1 1. 1734

A skilled person would appreciate that various techniques/algorithms could be implemented by the processing apparatus to determine whether the first coupling unit 210 and the modulation unit 280 are connected to the same network channel , based on the first reflectometry data. As an example the modulation unit 280 could apply a pre-defined sequence of changes as controlled by the analysis unit 150, the sequence of changes preferably being unique to the particular second port, that would e.g. provide a unique address. The inclusion of this unique address in first reflectometry data ("modulated TDR data") produced by the first reflectometry scanner 230 would indicate that the first and second ports of Fig. 12 are included in the same network channel, i.e. that the first and second ports are connected.

So far, the second network monitoring apparatus 200 has only been described with regard to determining whether a first port is included in the same network channel as a second port. However, these same principles cart be extended to provide a network apparatus that is configured to identify and/or map interconnections between a plurality of first ports and a plurality of second ports.

Accordingly, the above described second network monitoring apparatus 200 may have:

a plurality of the first coupling units 210, each first coupling unit 210 being associated with a respective first port included in a respective network channel of the network; and

a plurality of the modulation units 280, each modulation unit 280 being associated with a respective second port included in a respective network channel of the network;

wherein the processing apparatus is configured to produce reflectometry data representative of reflected reflectometry signals received by the first coupling units and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the first reflectometry data that involves one or more modulations caused by any one or more of the modulation units.

Preferably, the modulation units 280 are configured so that the one or more modulations caused by each modulation unit 280 is identifiable as being caused by that modulation unit 280, so as to allow the processing apparatus to identify or map interconnections between the first coupling units 210 and the modulation units 280 based on the reflectometry data. For example, this may be achieved by each modulation unit 280 being configured to cause one or more modulations at different times from the other modulation units 280, or by each modulation unit 280 being configured to cause one or more modulations that are distinguishable from the one or more modulations caused by other modulation units (e.g. such that the different modulation units 280 cause modulations having different frequencies).

Preferably, the network monitoring apparatus 200 is configured to repeatedly determine whether two ports are included in the same network chennel. E.g. the or each first coupling unit 210 may be configured to repeatedly couple a (respective) reflectometry signal to a (respective) network channel. E.g. the or each modulation unit 280 may be configured to modulate a (respective) signal propagating in the (respective) network channel that includes the

(respective) second port. The processing apparatus 200 may be configured to repeatedly produce reflectometry data representative of a (respective) reflected reflectometry signal received by the or each first coupling unit 210 and to repeatedly determine whether a first port is included in the same network channel as a second port, based on an analysis of the reflectometry data that involves one or more modulations caused by a modulation unit 280.

If the second network monitoring apparatus 200 is for identifying and/or mapping interconnections between the first ports and the second ports in a network that includes a plurality of network channels as described above, then the processing means may be configured to repeatedly update a map of interconnections, based on an analysis of the reflectometry data that includes repeatedly identifying any new interconnections between first ports and second ports and/or repeatedly identifying any lost interconnections between first ports and second ports. The "map" may be a list of interconnections, for example.

Fig. 13 is a plot that shows an simulated example of first reflectometry data produced if the modulation unit 280 is not modulating signals propagating within the network channel 1 (dotted line) and if the modulation unit 280 is modulating signals propagating in the network channel 1 (solid line). Again, the data is shown in the time domain (as "TD data" or as a "TDR plot"), with signal strength being used as the vertical axis and distance (in metres) being used as the horizontal axis.

As can be seen from Fig. 13, the modulations caused by the modulation unit 280 creates modulations in the first reflectometry data that could be used to determine whether the first coupling unit 210 and the modulation unit 280 are connected to the same network channel 1 , e.g. as described above.

Figs. 14(a) and (b) are plots that show examples of noise received by a coupling unit (not shown) configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel.

In Fig. 14(a), the plot shows noise received by the coupling unit whilst no data signals are propagating within any twisted pairs of the network channel. In Fig. 14(b), the plot shows noise received by the coupling unit whilst one or more data signals are propagating within one or more twisted pairs of the network channel.

As can be seen from Figs. 14(a) and (b), the noise floor of the signal received by the coupling unit is indicative of whether one or more data signals are propagating within one or more twisted pairs of the network channel, in that the noise floor increases when one or more data signals are propagating within one or more twisted pairs of the network channel.

Fig. 15 shows a third network monitoring apparatus 300 as applied to the network channel 1 shown in Fig. 2.

The third network monitoring apparatus 300 has many of the same components as the first network monitoring apparatus 100 shown in Fig. 3 and described above. Alike components have been given alike reference numerals, and need not be described in further detail.

In the third monitoring apparatus 300, the functionality of the first reflectometry scanner 130 and the second reflectometry scanner 140 is incorporated into the processing apparatus 300.

As noted above, both the first coupling unit 110 and the second coupling unit 120 are preferably, respectively, a coupling unit as described in UK patent application GB0905361.2 or GB1106054.8, also by the present inventors. These patent applications each describe coupling units suitable for receiving a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with twisted pairs of the network channel. Advantageously, this may allow the first and/or second coupling units 110, 120 to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel in a non-invasive manner.

Preferably, the processing apparatus 300 is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit 110 based on an analysis of a signal received by the first coupling unit 110, more preferably based on an analysis of whether a noise floor of a signal received by the first coupling unit 110 exceeds a predetermined threshold.

For example, the processing apparatus 300 could be configured to determine that one or more data signals are propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the first coupling unit 110 exceeds a predetermined threshold and/or to determine that one or more data signals are propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the first coupling unit 110 is less than (or does not exceed) the predetermined threshold.

Similarly, preferably the processing apparatus 300 is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit 0 based on an analysis of a signal received by the second coupling unit 120, more preferably based on an analysis of whether a noise floor of a signal received by the second coupling unit 120 exceeds a predetermined threshold.

For example, the processing apparatus 300 could be configured to determine that one or more data signals are propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the second coupling unit 120 exceeds a predetermined threshold and/or to determine that one or more data signals are propagating within one or more twisted pairs of the network channel if a noise floor of a signal received by the second coupling unit 120 is less than (or does not exceed) the predetermined threshold.

For the avoidance of any doubt, the signal received by the first coupling unit 110 and/or the signal received by the second coupling unit 120 need not have been a signal that was coupled to the network channel by a coupling unit configured to couple a signal to a network channel such that the signal propagates along the network channel between at least two twisted pairs in the network channel. For example, the signal received by the coupling unit may be entirely noise (on the pair-to-pair channel).

Preferably, the processing apparatus 300 is further configured to determine whether the first port is included in the same network channel as the second port, based on a comparison of one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit 110 with one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit 120.

In this way, the network monitoring apparatus is able to make a determination as to whether two ports are included in the same network channel without adding any signals (pair-to-pair signals or otherwise) to the network channel(s) and in a non-invasive manner.

The processing apparatus 300 could, however, be configured to determine whether the first port is included in the same network channel as the second port based on other ways of comparing a signal received by the first coupling unit 110 and a signal received by the second coupling unit 120.

For example, the processing apparatus 300 may be configured to determine whether the first port is included in the same network channel as the second port based on a cross-correlation of a signal received by the first coupling unit 110 and a signal received by the second coupling unit 120.

When used in this specification and claims, the terms "comprises" and "comprising", "including" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or integers.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be involved for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure, without departing from the broad concepts disclosed. It is therefore intended that the scope of the patent granted hereon be limited only by the appended claims, as interpreted with reference to the description and drawings, and not by limitation of the embodiments described herein.

ANNEX - COPY OF UK PATENT APPLICATION GB1106054.8

In this copy of UK patent application GB1106054.8, the figures have been renumbered to avoid conflict with the other figures in this patent application, references to published applications have been updated, and the claims have been relabelled as "statements" to avoid confusion with the claims of this patent application.

COUPLING UNIT FOR USE WITH A TWISTED PAIR CABLE AND ASSOCIATED APPARATUSES AND METHODS

This invention generally relates to a coupling unit for use with a twisted pair cable, preferably for use with a shielded twisted pair cable, e.g. of a type widely used in local area networks. This invention also generally relates to apparatuses and methods associated with such a coupling unit. For example, the invention may further relate to a network monitoring apparatus, e.g. for identifying one or more interconnections between network ports within a network and/or for determining the physical condition or state of one or more channels within a network.

The terminology used to describe shielded twisted pair cables varies from manufacturer to manufacturer. For consistency, a shielded twisted pair cable including electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs but does not include an outer electromagnetic shielding that surrounds all twisted pairs is herein referred to as an "STP" cable (outside of this patent application, such cables can sometimes be referred to as "shielded twisted pair" or "screened twisted pair" cables, but this is avoided in the present application where the term "shielded twisted pair" cable is reserved for identifying a twisted pair cable that includes any form of electromagnetic shielding). A shielded twisted pair cable including an outer electromagnetic shielding (e.g. foil) that surrounds all twisted pairs but does not include electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs is herein referred to as a "foil/unshielded twisted pair" or "F/UTP" cable. A twisted pair cable including both electromagnetic shielding arranged to shield each twisted pair from the other twisted pairs and an outer electromagnetic shielding that surrounds all twisted pairs is herein referred to as a "screened fully shielded twisted pair" or "S/FTP" cable (sometimes "S/STP" is also used to describe this type of cable).

Telecommunications networks, e.g. local area networks (LANs), are also well known. Local area networks are typically used to enable equipment such as computers, telephones, printers and the like to communicate with each other and with remote locations via an external service provider. Local area networks typically utilise twisted pair network cables, usually in the form of unshielded twisted pair cables, although in some case shielded twisted pair cables such as STP or F/UTP may be employed. The twisted pair cables generally interconnect network ports within the network to form one or more network lines (or "channels") through which data can be communicated.

A "patch system" may be used to interconnect various network lines of the local area network within the network cabinets. In a patch system, all of the network lines can be terminated within the network cabinets in an organized manner. The terminations of the network lines are provided by the structure of the network cabinets, which are typically organised in a rack system. The racks contain "patch panels", which themselves utilise sets of network ports, typically RJ45-type or screened RJ45-type connector ports, at which the network lines terminate.

Each of the network ports in each patch panel is generally wired to one of the local area network's network lines.

Accordingly, each network line is terminated on a patch panel in an organized manner. In small patch systems, all network lines may terminate on the patch panels of the same rack. In larger patch systems, multiple racks are used, wherein different network lines terminate on different racks.

The interconnections between the various network lines are made using "patch" cables, which are typically shielded or unshielded twisted pair cables including four twisted pairs. Each end of a patch cable is terminated by a connector, such as an RJ-45 type connector for inserting into an RJ-45 type connector port as described above. One end of the patch cable is connected to the network port of a first network line and the opposite end of the patch cable is connected to the network port of a second network line. By selectively connecting the various network lines using the patch cables, a desired combination of network interconnections can be achieved.

Fig. 16 shows a typical patch system organised into a server row, a cross-connect row and a network row, which include four patch panels. Four patch cables are used to interconnect two network lines through the patch system.

Fig. 17 shows an example of a typical patch panel viewed from an edge of the casing of a patch panel. "Fixed", e.g. permanently installed, cables are located on one side of (internally within) the patch panel, in this case shown at the top of the drawing, and the patch cables (aka "patch leads") are located on the opposite side of (outside) the patch panel, in this case shown at the bottom of the drawing. The fixed cables are wired to network ports (aka "patch ports") of the patch panel and, as shown here, not all the network ports of the patch panel necessarily have a patch cable inserted. The network ports are typically an RJ45-type socket or similar socket connector whereas the patch cables typically contain a RJ-45 type plug or similar plug connector. The network port sockets of the patch panel typically have a defined mechanical fixing and in many cases can be demounted from the patch port.

In many businesses, employees are assigned their own computer network access number so that the employee can interface with the companies IT infrastructure. When an employee changes office locations, it is not desirable to provide that employee with newly addressed network port. Rather, to preserve consistency in communications, it is preferred that the exchanges of the network ports in the employee's old office be transferred to the telecommunications ports in the employee's new location. This type of move is relatively frequent. Similarly, when new employees arrive and existing employees depart, it is usually necessary for the patch cables in the network cabinet(s) to be rearranged so that each employee's exchanges can be received in the correct location.

As the location of employees change, the patch cables in a typical cabinet are often manually entered in a computer based log. This is burdensome. Further, technicians often neglect to update the log each and every time a change is made. Accordingly, the log is often less than 100% accurate and a technician has no way of reading where each of the patch cables begins and ends. Accordingly, each time a technician needs to change a patch cable, that technician manually traces that patch cable between an internal line and an external line. To perform a manual trace, the technician locates one end of a patch cable. The technician then manually follows the patch cable until he/she finds the opposite end of that patch cable. Once the two ends of the patch cable are located, the patch cable can be positively identified.

It takes a significant amount of time for a technician to manually trace a particular patch cable, especially in large patch systems. Furthermore, manual tracing is not completely accurate and a technician may accidently go from one patch cable to another during a manual trace. Such errors result in misconnected patch cables which must be later identified and corrected.

In another embodiment of US Patent Number 5463467, the scanner is coupled to each data port by "dry contact" with a dedicated conductor in a patch cable. This is difficult to implement in practice, because most network cables have to meet a particular pre-determined standard in the industry, such as RJ45, in which there is no free conductor which could be used for determining interconnectivity.

International Patent Application Publication Number WO2005n 09015, also by the present inventors, which relates to the field of cable state testing, discloses a method of determining the state of a cable comprising at least one electrical conductor and applying a generated test signal to at least one conductor of the cable by a non-electrical coupling transmitter. The reflected signal is then picked up and compared with expected state signal values for the cable, so that the state of the cable can be determined. The inventors have found that signals coupled to a twisted pair cable by the methods described in WO2005/109015 have a tendency to leak out from the twisted pair cable, especially when other twisted pair cables are nearby.

UK patent application GB0905361.2, also by the present inventors, describes an invention which relates to apparatuses and methods for coupling a signal to andtor from a cable which includes a plurality of twisted pairs. In particular, this invention relates to coupling a signal to and/or from such a cable by non-contact (capacitive) coupling with the cable. Such signals may be used to determine interconnections, e.g. within a local area network. The disclosure of

GB0905361.2 generally relates to a discovery that a twisted pair cable, e.g. an unshielded twisted pair (UTP) cable, provides communication channels which are additional to the respective communication channel provided within each twisted pair in the cable. In particular, it has been found that additional communication channels exist between each combination of two twisted pairs within a twisted pair cable, due to coupling between the twisted pairs. Each combination of two twisted pairs within a twisted pair cable has been termed a "pair-to-pair" combination. Therefore, the additional communication channels may be termed "pair-to-pair" channels. GB0905361.2 discloses that a signal which propagates along a twisted pair cable between two of the twisted pairs can propagate reliably and over useful distances, without significantly altering the transmission of signals within the individual twisted pairs. Consequently, the "pair-to-pair" signal can propagate in addition to the differential voltage signals which typically propagate within each twisted pair when the twisted pair cable is in use. Therefore test signals can be introduced into the "pair-to-pair" channel and these "pair-to- pair" signals can be used to monitor the operation of the network without disrupting the normal operation of the network.

UK patent application GB1009184.1 (published as GB2480830), also by the present inventors, discloses signal processing apparatuses and methods for use with a plurality of cable lines (aka "network channels" or "network lines"), such as those including one or more twisted pair cables. In particular, GB1009184.1 relates to apparatuses and methods for analysing one or more characteristics of a test signal coupled out from one of a plurality of cable lines. GB1009184.1 presents apparatuses and methods for analysing a characteristic of a test signal, which may be a "pair-to-pair" signal to determine whether that test signal has propagated directly to the coupling unit via a single cable line or has propagated indirectly to the coupling unit via crosstalk between different cable lines.

UK patent application GB1018582.5 (published as GB2480830), also by the present inventors, discloses apparatuses for identifying interconnections in a network comprising a plurality of cable lines and/or for determining the physical state (i.e. condition) of cable lines in the network.

The content of UK patent applications GB0905361.2, GB1009184.1 and GB1018582.5 is incorporated herein by reference.

A limitation of the apparatuses and methods disclosed in UK patent applications GB0905361.2, GB1009184.1 and GB1018582.5, is that these apparatuses and methods are generally designed to be used with unshielded twisted pair (UTP) cables, and may therefore be unsuitable for use with shielded twisted pair cables. For example, the coupling units shown and described in GB0905361.2 have electrodes for coupling a signal into a twisted pair cable that is positioned between the electrodes. Such electrodes would not, in general, be able to transmit/receive a voltage signal toVfrom a shielded twisted pair cable, since the shielding (e.g. which may surround all twisted pairs in an F/UTP cable, or which may surround the individual twisted pairs in an STP cable) will generally prevent the electrodes from coupling with the twisted pairs, and therefore will generally prevent the electrodes from transmitting/receiving a voltage signal to/from the twisted pairs.

The present invention has been devised in light of the above considerations.

In general, the present invention relates to a coupling unit for use with a twisted pair cable, preferably a shielded twisted pair cable, the coupling unit having a plurality of conductive elements, each conductive element being configured to be electrically connected to a respective conductor of a twisted pair cable, and at least one electrode configured to transmit a voltage signal to the one or more conductive elements and/or to receive a voltage signal from the one or more conductive elements by non-contact (preferably capacitive) coupling with the one or more conductive elements.

In this way, a voltage signal transmitted to the one or more conductive elements can propagate along a twisted pair cable via one or more conductors of the twisted pair cable electrically connected to the one or more conductive elements (e.g. if the coupling unit is physically connected to the twisted pair cable by an interface of the coupling unit). Similarly, a voltage signal can be received by the one or more conductive elements after the voltage signal has propagated along a twisted pair cable via one or more conductors of a twisted pair cable electrically connected to the one or more conductive elements (e.g. if the coupling unit is physically connected to the twisted pair cable by an interface of the coupling unit).

For the avoidance of any doubt, when a signal is described as propagating along a twisted pair cable, it might, but need not, propagate along the entire length of the twisted pair cable.

Advantageously, the coupling unit can be used to transmit/receive a voltage signal, not just to/from the conductors of a UTP cable, but also to/from the conductors of a shielded twisted pair cable. This is because the conductive elements permit the electrodes to couple (indirectly, via the conductive elements) with one or more conductors of the shielded twisted pair cables. As noted above, this was generally not possible with the apparatuses and methods disclosed in UK patent applications GB0905361.2, 6B100918 .1 and GB1018582.5, also by the present inventors.

A first aspect of the invention may provide:

a coupling unit for use with a twisted pair cable, preferably a shielded twisted pair cable, the coupling unit having:

an interface for physically connecting the coupling unit to a twisted pair cable;

a plurality of conductive elements, each conductive element being configured to be electrically connected to a respective conductor of a twisted pair cable, if the coupling unit is physically connected to the twisted pair cable by the interface; and

at least one electrode that is adjacent to one or more conductive elements of the coupling unit, the at least one electrode being configured to transmit a voltage signal to the one or more conductive elements and/or to receive a voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

Herein, it should be appreciated that "non-contact" coupling preferably refers to coupling that does not involve direct electrical ("ohmic") contact, preferably capacitive coupling. Thus, whilst the "non-contact" coupling between the or each electrode and the at least one conductive elements should not involve direct electrical contact between the or each electrode and the at least one conductive element, it would be possible, for example, for the at least one conductive element to be protected by an electrically insulative sheath and for the or each electrode to be in physical contact with the electrically insulative sheath.

Herein, it should be appreciated that describing an electrode as being "adjacent^* to one or more coupling elements preferably refers to the electrode being near to the one or more conductive elements, preferably with little or substantially no electromagnetic shielding being between the electrode and the one or more conductive elements.

The voltage signal is preferably a differential voltage signal. A differential voltage signal can be understood as a voltage signal that includes a first voltage signal that is transmitted/received via a first signal path and a second voltage signal that is transmitted/received via a second signal path, the second voltage signal being complimentary (preferably opposite) to the first voltage signal. A differential voltage signal can also be understood as a voltage signal that propagates between the first and second signal paths. These two different views of a differential voltage signal are essentially equivalent. Although preferably a differential voltage signal, the voltage signal may instead be a single-ended voltage signal. A single-ended voltage can be viewed as including only one voltage signal that varies with respect to a fixed voltage, e.g. a local ground. This is different from a differential voltage, which includes two complimentary voltage signals.

A differential voltage signal is preferred because it has been found to propagate more reliably than a single-ended voltage signal.

UK patent application GB0905361.2, also by the present inventors, taught transmitting a voltage signal to the twisted pairs of a twisted pair cable using a pair of electrodes arranged to produce an electric field therebetween. A similar arrangement of electrodes was taught for the receiving of a voltage signal after it had propagated along a twisted pair cable. This arrangement of electrodes allowed a differential voltage signal to be transmitted to the twisted pair cable such that the signal propagated along the cable between at least two of the twisted pairs, and further allowed a differential voltage signal to be received from the cable after the signal had propagated along the cable between at least two of the twisted pairs. The differential voltage signal was thought to result from an electric field produced between the pair of electrodes which caused a difference in voltage between the twisted pairs.

A similar electrode arrangement could be used with the present invention so as to produce a voltage signal that propagates between twisted pairs of a twisted pair cable. For example, the at least one electrode could include a pair of electrodes that are adjacent to (e.g. located on opposite sides of) a plurality of conductive elements of the coupling unit that are respectively electrically connected to the conductors of a twisted pair cable, the pair of electrodes being configured to: produce an electric field therebetween to transmit a (differential) voltage signal to the conductive elements by non-contact coupling with the conductive elements so that the voltage signal propagates along the twisted pair cable between at least two of the twisted pairs; and/or configured to receive a (differential) voltage signal from the plurality of conductive elements by non-contact coupling with the plurality of conductive elements after the voltage signal has propagated along the twisted pair cable between at least two of the twisted pairs.

However, this electrode arrangement was devised for a coupling unit that could potentially be clipped to the outside of an unshielded twisted pair cable. In the present case, the coupling unit includes a plurality of conductive elements configured to be electrically connected to the conductors of a twisted pair cable if the coupling unit is physically connected to the twisted pair cable by the interface. This means that the electrode can be selectively placed adjacent to one or more of the conductive elements whilst e.g. being electromagnetically shielded from the others. This permits many different electrode arrangements which may be preferred to the electrode arrangement described in UK patent application GB0905361.2, also by the present inventors.

A preferred electrode arrangement, described below in more detail, involves the coupling unit having at least one first electrode adjacent to one or more first conductive elements of the coupling unit and at least one second electrode adjacent to one or more second conductive elements of the coupling unit, these electrodes preferably being configured so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the first and second electrodes can transmit and/or receive a differential voltage signal to and/or from the first and second conductive elements by non- contact coupling with the first and second conductive elements.

Another, simpler, electrode arrangement, also described below in more detail, involves the coupling unit having at least one electrode that is adjacent to one or more conductive elements of the coupling unit, the at least one electrode preferably being configured so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the at least one electrode can transmit and/or receive a single-ended voltage signal to and/or from the one or more conductive elements by non-contact coupling with the one or more conductive elements. Here a local ground may act as a return path for the single-ended voltage signal. Preferably, the local ground is provided by electromagnetic shielding of the twisted pair cable, since this may provide a stable ground by which the single-ended voltage signal can reliably propagate. Preferably, the coupling unit has:

at least one first electrode that is adjacent to one or more first conductive elements of the coupling unit; and at least one second electrode that is adjacent to one or more second conductive elements of the coupling unit.

This electrode arrangement is preferred because it allows a differential voltage signal to be transmitted and/or received to a twisted pair cable.

Preferably, therefore, the at least one first electrode and the at least one second electrode are configured to transmit a differential voltage signal to the first and second conductive elements by non-contact coupling with the first and second conductive elements (preferably so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the differential voltage signal can propagate along the twisted pair cable between the conductor(s) of the twisted pair cable electrically connected to the one or more first conductive elements and the conductor(s) of the twisted pair cable electrically connected to the one or more second conductive elements) and/or to receive a differential voltage signal from the first and second conductive elements by non-contact coupling with the first and second conductive elements (preferably so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the differential voltage signal can be received after it has propagated along the twisted pair cable between the conductors) of the twisted pair cable electrically connected to the one or more first conductive elements and the conductor(s) of the twisted pair cable electrically connected to the one or more second conductive elements).

Preferably, the coupling unit includes electromagnetic shielding arranged to shield the at least one first electrode from the at least one second electrode and/or electromagnetic shielding arranged to shield the one or more first conductive elements from the one or more second conductive elements. In this way, degradation of a differential voltage signal transmitted and/or received by the first and second electrodes can be reduced. The same portion of electromagnetic shielding may act as both the electromagnetic shielding arranged to shield the at least one first electrode from the at least one second electrode and the electromagnetic shielding arranged to shield the one or more first conductive elements from the one or more second conductive elements.

The coupling unit may include electrodes that are dedicated either to transmitting or receiving a voltage signal.

Accordingly, the coupling unit may have:

at least one first transmitter electrode that is adjacent to one or more first conductive elements of the coupling unit; and/or

at least one second transmitter electrode that is adjacent to one or more second conductive elements of the coupling unit;

wherein the at least one first transmitter electrode and the at least one second transmitter electrode are configured to transmit a differential voltage signal to the first and second conductive elements by non-contact coupling with the first and second conductive elements.

Similarly, the coupling unit may have:

at least one first receiver electrode that is adjacent to one or more first conductive elements of the coupling unit; and/or

at least one second receiver electrode that is adjacent to one or more second conductive elements of the coupling unit;

wherein the at least one first receiver electrode and the at least one second receiver electrode are configured to receive a differential voltage signal from the first and second conductive elements by non-contact coupling with the first and second conductive elements. Preferably, the one or more first conductive elements adjacent to the at least one first transmitter electrode are the same as the one or more first conductive elements adjacent to the at least one first receiver electrode. Similarly, the one or more second conductive elements adjacent to the at least one second transmitter electrode are the same as the one or more second conductive elements adjacent to the at least one second receiver electrode, but this need not be the case.

If the coupling unit includes both transmitter and receiver electrodes, it preferably includes electromagnetic shielding arranged to shield the transmitter electrodes from the receiver electrodes, e.g. so as to inhibit a signal being transmitted directly therebetween.

For the avoidance of any doubt, whilst the coupling unit may includes both transmitter and receiver electrodes, it is also possible for the coupling unit to include only transmitter electrodes or only receiver electrodes.

Although the at least one first electrode and the at least one second electrode may include electrodes that are dedicated either to transmitting or receiving a voltage signal, it is also possible for the same at least one first electrode and the same at least one second electrode to be configured to both transmit and receive a voltage signal. Accordingly, the coupling unit may have:

at least one first transceiver electrode that is adjacent to the one or more first conductive elements of the coupling unit; and

at least one second transceiver electrode that is adjacent to the one or more second conductive e/emente of the coupling unit;

wherein the at least one first transceiver electrode and the at least one second transceiver electrode are configured to transmit a differential voltage signal to the first and second conductive elements by non-contact coupling with the first and second conductive elements and to receive a differential voltage signal from the first and second conductive elements by non-contact coupling with the first and second conductive elements.

Configuring a transceiver electrode to both transmit and receive a voltage signal may be achieved, for example, using a directional coupler, which component is well known e.g. in the art of radio technology. Having transceiver electrodes configured to both transmit and receive a voltage signal may be advantageous in reducing the amount of space occupied by the electrodes, especially if there is little space for the electrodes in the coupling unit.

In some embodiments, the at least one electrode (which could be one solitary electrode) adjacent to the one or more conductive elements may be configured to transmit a single-ended voltage signal to the one or more conductive elements by non-contact coupling with the one or more conductive elements (preferably so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the single-ended voltage signal can propagate along the twisted pair cable via conductors) of the twisted pair cable electrically connected to the one or more conductive elements) and/or to receive a single-ended voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements (preferably so that, if the coupling unit is physically connected to a twisted pair cable by the interface, the single-ended voltage signal can be received after it has propagated along the conductor(s) of the twisted pair cable electrically connected to the one or more conductive elements).

Here a local ground may act as a return path for the single-ended voltage signal. Preferably, the local ground is provided by electromagnetic shielding of the twisted pair cable, since this may provide a stable ground by which the single-ended voltage signal can reliably propagate. Preferably, to facilitate this, the coupling unit includes electromagnetic shielding configured to electrically connect to electromagnetic shielding of a shielded twisted pair cable, if the coupling unit is physically connected to the shielded twisted pair cable by an interface (e.g. a first or second interface) of the coupling unit.

The coupling unit may include one or more electrodes that are dedicated either to transmitting or receiving a single- ended voltage signal.

Accordingly, the coupling unit may have: at least one transmitter electrode adjacent to one or more conductive elements, the at least one transmitter electrode being configured to transmit a single-ended voltage signal to the one or more conductive elements by non- contact coupling with the one or more conductive elements.

Similarly, the at least one electrode may have:

at least one receiver electrode adjacent to one or more conductive elements, the at least one receiver electrode being configured to receive a single-ended voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

If the coupling unit includes both at least one transmitter and at least one receiver electrode, it preferably includes electromagnetic shielding arranged to shield the at least one transmitter electrode from the at least one receiver electrode, e.g. so as to inhibit a signal being transmitted directly therebetween.

For the avoidance of any doubt, whilst the coupling unit may includes both transmitter and receiver electrodes, it is also possible for the coupling unit to include only one or more transmitter electrodes or one or more receiver electrodes.

Although the at least one electrode may include electrodes that are dedicated either to transmitting or receiving a voltage signal, it is also possible for the same at least one electrode to be configured to both transmit and receive a voltage signal. Accordingly, the coupling unit may have:

at least one transceiver electrode adjacent to one or more conductive elements of the coupling unit, the at least one transceiver electrode being configured to transmit a single-ended voltage signal to the one or more conductive elements by non-contact coupling with the one or more conductive elements and to receive a single-ended voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

Configuring a transceiver electrode to both transmit and receive a voltage signal may be achieved, for example, using a directional coupler, which component is well known e.g. in the art of radio technology. Having transceiver electrode(s) configured to both transmit and receive a voltage signal may be advantageous in reducing the amount of space occupied by the electrodes, especially if there is little space for the electrodes in the coupling unit.

Preferably, the twisted pair cable is a shielded twisted pair cable, i.e. preferably the twisted pair cable includes electromagnetic shielding, e.g. as described above.

Preferably, the coupling unit includes electromagnetic shielding. As has already been discussed above, electromagnetic shielding included in the coupling unit may include any one or more of: electromagnetic shielding arranged to shield at least one first electrode from at least one second electrode; electromagnetic shielding arranged to shield one or more first conductive elements from one or more second conductive elements; and/or electromagnetic shielding arranged to shield at least one transmitter electrode from at least one receiver electrode. Additionally, or alternatively, the coupling unit may include electromagnetic shielding arranged to shield the conductive elements from external electromagnetic interference for the coupling unit and/or reduce crosstalk between coupling units. The electromagnetic shielding arranged to shield the conductive elements from external electromagnetic interference for the coupling unit and/or reduce crosstalk between coupling units may be provided, for example, by a metal shell, e.g. which may be included in a housing of the coupling unit (e.g. as discussed below).

If the coupling unit includes (any) electromagnetic shielding, the electromagnetic shielding of the coupling unit is preferably configured to electrically connect to electromagnetic shielding of a shielded twisted pair cable, if the coupling unit is physically connected to the shielded twisted pair cable by an interface (e.g. a first or second interface) of the coupling unit. This may allow shielding of the coupling unit and twisted pair cable to provide a stable ground by which a voltage signal can reliably propagate.

If the coupling unit includes (any) electromagnetic shielding, the electromagnetic shielding of the coupling unit is preferably configured to electrically connect to a local ground, as electromagnetic shielding is generally more effective when connected to a ground. Preferably, the interface of the coupling unit is one of two interfaces, preferably such that the conductive elements of the coupling unit can be used to electrically interconnect the conductors of two different twisted pair cables. This is preferable because it allows the interface of the coupling unit to be inserted into the middle of a channel including a plurality of twisted pair cables, rather than at the end of such a channel.

Accordingly, the coupling unit preferably includes:

a first interface for physically connecting the coupling unit to a first twisted pair cable;

a second interface for physically connecting the coupling unit to a second twisted pair cable;

wherein each conductive element of the coupling unit is configured to be electrically connected to a respective conductor of a first twisted pair cable and a respective conductor of a second twisted pair cable, if the coupling unit is physically connected to the first twisted pair cable by the first interface and to the second twisted pair cable by the second interface.

The first and/or second interface may be a plug (e.g. outwardly projecting or "male") interface or socket (e.g. inwardly projecting or "female") interface, depending on design requirements. The first and/or second interface may conform to a standard for twisted pair cables, e.g. RJ45.

Preferably, the conductive elements of the coupling unit are grouped in one or more pairs, with the or each pair of conductive elements being configured to be electrically connected to both (e.g. forward and return) conductors of a respective twisted pair of a twisted pair cable, if the twisted pair cable is physically connected to the coupling unit by the interface. If the coupling unit includes a first interface and a second interface, then each pair of conductive elements is preferably configured to be electrically connected to both (e.g. forward and return) conductors of a respective twisted pair of a first twisted pair cable and both (e.g. forward and return) conductors of a respective twisted pair of a second twisted pair cable, if the coupling unit is physically connected to the first twisted pair cable by the first interface and to the second twisted pair cable by the second interface.

Preferably, the or each electrode of the coupling unit is adjacent to one or more pairs of conductive elements of the coupling unit. Thus, where "one or more ... conductive elements" are mentioned herein, this can be replaced by "one or more ... pairs of conductive elements". For example, "at least one electrode that is adjacent to one or more conductive elements" may be replaced by "at least one electrode that is adjacent to one or more pairs of conductive elements". Similarly, "at least one first electrode that is adjacent to one or more first conductive elements" may be replaced by "at least one first electrode that is adjacent to one or more first pairs of conductive elements".

An advantage of having the or each electrode of the coupling unit adjacent to one or more pairs of conductive elements is that the or each pair of conductive elements can be electrically connected to both (e.g. forward and return) conductors of a respective twisted pair in a twisted pair cable, if the twisted pair cable is physically connected to the coupling unit by the interface. In this way, a voltage signal transmitted to a pair of conductive elements by an electrode of the coupling unit is able to propagate along both (e.g. forward and return) conductors of a twisted pair in the twisted pair cable. This is advantageous because a voltage signal that propagates along both (e.g. forward and return) conductors of a twisted pair will generally not interrupt any differential voltage signal (e.g. a data signal) propagating within the twisted pair (i.e. between the forward and return conductors of the twisted pair).

Usually, a twisted pair cable includes a plurality of twisted pairs, in which case the coupling unit preferably includes a corresponding plurality of pairs of conductive elements. In this case, the coupling unit preferably includes

electromagnetic shielding arranged to shield each pair of conductive elements from the other pair(s) of conductive elements. In this way, cross-coupling between the pairs of conductive elements can be reduced.

An aforementioned electrode may take the form of an electrode described, for example, in UK patent application number GB0905361.2, also by the present inventors. For example, the or each electrode of the coupling unit may be provided in the form of a (respective) plate. The or each plate may be made of, for example, foil, e.g. copper foil.

Preferably, the or each plate has an area of 10 mm² (e.g. 3.16 mm by 3.16 mm) or larger. More preferably, the or each plate has an area 20 mm² (e.g. 4.47 mm by 4.47 mm) or larger, more preferably an area that is approximately equal to 20mm². The inventors have found that plates having such areas are large enough to transmit receive a voltage signal to/from a twisted pair cable using the coupling unit such that the voltage signal propagates over useful distances, e.g. up to 100 metres.

The or each electrode (e.g. plate) may be constructed as described in UK patent application GB1018582.5 (from which published application WO2012)059722 claims priority) and/or as shown in Figs. 7(a)-(c) below.

Accordingly, one or more electrodes of the coupling unit may be located (preferably printed) on one or more flexible circuit boards, e.g. of a suitable material such as polyimide. A ground plane may be located (preferably printed) on an opposite side of the or each flexible circuit board to the or each electrode. The ground plane may serve a useful electromagnetic screening/shielding role for the or each electrode and, as such, may form e.g. a part of electromagnetic shielding of the coupling unit.

The coupling unit preferably has a housing or main body. The housing preferably houses at least some or all of the aforementioned components. For example, the housing may house the or each electrode. Similarly, the housing may contain the conductive elements. The housing preferably includes mechanical elements, e.g. lugs, bevels, and/or retaining clips, for attaching the coupling unit to an external apparatus, e.g. a patch panel. Preferably, the housing includes an electrically insulative (preferably plastic) inner body surrounded by an electrically conductive (preferably metal) shell. Here, the electrically conductive shell may provide electromagnetic shielding for the coupling unit, e.g. electromagnetic shielding arranged to shield the conductive elements from external electromagnetic interference and/or reduce crosstalk between coupling units.

Preferably, the coupling unit includes one or more connectors for connecting the at least one electrode to a voltage signal producing and/or processing apparatus.

For example, the coupling unit may include one or more connectors for conveying a voltage signal produced by a voltage signal producing and/or processing apparatus to at least one electrode of the coupling unit (e.g. at least one transmitter or transceiver electrode), e.g. so that the at least one electrode can transmit the voltage signal and/or for conveying a voltage signal received by at least one electrode of the coupling unit (e.g. at least one receiver or transceiver electrode) to a voltage signal producing and/or processing apparatus, e.g. so that the voltage signal can be processed by the voltage signal producing and/or processing apparatus.

The or each connector may, for example, take the form of a twisted pair cable (shielded or unshielded), a coaxial cable or even a portion of a flexible circuit board. In any case, the or each connector is preferably designed to ensure that any coupling between connectors (or between the conductors within the connectors) is small or negligible compared with the coupling between the at least one electrode and the one or more conductive elements.

One or more of the coupling units may be included in an apparatus having a voltage signal producing and/or processing apparatus configured.

to produce a voltage signal and to convey the voltage signal to at least one electrode of the coupling unit (e.g. at least one transmitter or transceiver electrode), preferably such that the voltage signal is transmitted by the at least one electrode; and/or

to process a voltage signal conveyed from at least one electrode of the coupling unit (e.g. at least one receiver or transceiver electrode), preferably after the voltage signal has been received by the at least one electrode.

The voltage signal producing and/or processing apparatus may, for example, include a voltage signal generator for producing the voltage signal and/or a separate voltage signal processor for processing the voltage signal. Components of the voltage signal producing and/or processing apparatus could be included in the coupling unit(s) rather than in the voltage signal generator and/or voltage signal processor. Preferably, however, the voltage signal producing and/or processing apparatus is configured to both produce and process a voltage signal, i.e. it is preferably a voltage signal producing and processing means. A voltage signal producing and processing means may, for example, be a vector network analyser ("VNA"), for example.

The one or more coupling units are preferably connected to the voltage signal producing and/or processing apparatus, e.g. using one or more connectors of the or each coupling units, e.g. as described above.

The voltage signal producing and/Or processing apparatus may be configured to convey a voltage signal to at least one electrode of the coupling unit via a connector, e.g. as described above. Similarly, the voltage signal producing and/or processing apparatus may be configured to convey a voltage signal from at least one electrode of the coupling unit via a connector, e.g. as described above.

Preferably, the voltage signal producing and/or processing apparatus is configured to produce and/or process a differential voltage signal. For example, the voltage signal producing and/or processing apparatus may be configured to work with the electrode arrangement described above in which the coupling unit has at least one first electrode adjacent to one or more first conductive elements and at least one second electrode adjacent to one or more second conductive elements. Accordingly, the voltage signal producing and/or processing apparatus is preferably configured:

to produce a differential voltage signal and to convey the differential voltage signal to at least one first electrode of the coupling unit (e.g. at least one first transmitter electrode or at least one first transceiver electrode) and at least one second electrode of the coupling unit (e.g. at least one second transmitter electrode or at least one second transceiver electrode), preferably such that the differential voltage signal is transmitted by the at least one first electrode and the at least one second electrode; and/or

to process a differential voltage signal conveyed from at least one first electrode of the coupling unit (e.g. at least one first receiver electrode or at least one first transceiver electrode) and at least one second electrode of the coupling unit (e.g. at least one second receiver electrode or at least one second transceiver electrode), preferably after the differential voltage signal has been received by the at least one first electrode and the at least one second electrode.

There are many different ways in which the voltage signal producing and/or processing apparatus could be configured to produce a differential voltage signal and convey it to at least one first electrode and at least one second electrode of the coupling unit. For example, the voltage signal producing and/or processing apparatus could include a voltage signal generator configured to produce a single-ended voltage signal and an electrical isolation means (e.g. a balun) configured to convert the single-ended voltage signal into a differential voltage signal before it is conveyed to the at least one first electrode and at least one second electrode of the coupling unit. A similar arrangement was taught in UK patent application number GB0905361.2, also by the present inventors. By way of example, the aforementioned electrical isolation means could be included in the coupling unit, e.g. as taught by UK patent application number GB0905361.2.

Similarly, there are many different ways in which the voltage signal producing and/or processing apparatus could be configured to process a differential voltage signal conveyed from at least one first electrode and at least one second electrode of the coupling unit. For example, the voltage signal producing and/or processing apparatus could include an electrical isolation means configured to convert the differential voltage signal into a single-ended voltage signal and a voltage signal processor configured to process the single-ended voltage signal. A similar arrangement was taught in UK patent application number GB0905361.2, also by the present inventors. By way of example, the aforementioned electrical isolation means could be included in the coupling unit, e.g. as taught by UK patent application number GB0905361.2.

In some embodiments, the voltage signal producing and/or processing apparatus is configured to produce and/or process a single-ended voltage signal. Accordingly, the voltage signal producing and/or processing apparatus may be configured: to produce a single-ended voltage signal and to convey the single-ended voltage signal to at least one electrode of the coupling unit (e.g. at least one transmitter electrode or at least one transceiver electrode), preferably such that the single-ended voltage signal is transmitted by the at least one electrode; and/or

to process a single-ended voltage signal conveyed from at least one electrode of the coupling unit (e.g. at least one receiver electrode or at least one transceiver electrode), preferably after the single-ended voltage signal has been received by the at least one electrode.

Preferably, the coupling unit is for use in a network monitoring apparatus, e.g. an apparatus for monitoring a network, e.g. a telecommunications network such as a local area network, e.g. having a plurality of cables which interconnect a plurality of network ports.

Accordingly, the first aspect of the invention may provide a network monitoring apparatus for monitoring a network, the network monitoring apparatus having:

one or more of the coupling units (e.g. twenty-four coupling units), the or each coupling unit being associated or configured to be associated with a respective network port in a network; and

a voltage signal producing and/or processing apparatus e.g. as described above, wherein the voltage signal producing and/or processing apparatus is configured to produce a voltage signal and to convey the voltage signal to at least one electrode of one or more of the coupling units and/or to process a voltage signal conveyed from at least one electrode of one or more of the coupling units.

The network monitoring apparatus may be configured to monitor a network, for example, by identifying one or more interconnections between network ports within a network (e.g. to produce a connection map of patch leads) and/or by determining the physical condition or state of one or more channels within a network.

Herein, the terms "channel", "network channel", "cable line" and "network line" preferably refer to a cable or a plurality of cables connected together so as to be capable of carrying a signal. These terms may be used interchangeably.

Preferably the one or more cables are twisted pair cables. The prefix "twisted pair" may be used with the terms "channel", "network channel", "cable line" and "network line" to indicate the presence of twisted pair cables within the channel.

Configuring the network monitoring apparatus to monitor a network by identifying one or more interconnections between network ports within a network may be achieved, for example, by the voltage signal producing and/or processing apparatus being configured to produce a voltage test signal and to convey the voltage test signal to (at least one electrode of) one of the coupling units, so that (the at least one electrode of) the coupling unit transmits the voltage test signal. If another coupling unit subsequently receives the voltage test signal, then an interconnection between the coupling unit that transmitted the voltage test signal and the coupling unit that received the voltage test signal can be identified, and therefore an interconnection between the network ports with which those coupling units are associated can be identified.

It should be appreciated that this is not the only way in which interconnections between network ports can be identified. Other methods and apparatuses for identifying interconnections between coupling units are disclosed, for example, in UK patent applications GB0905361.2, GB1009184.1 and GB1018582.5, also by the present inventors.

Configuring the network monitoring apparatus to monitor a network by determining the physical condition or state of one or more channels within the network may be achieved, for example, by the voltage signal producing and/or processing apparatus being configured to produce a voltage test signal and to convey the voltage test signal to (at least one electrode of) one of the coupling units, so that (the at least one electrode of) the coupling unit transmits the voltage test signal so that it propagates along a channel to which it is connected. If the same (or another) coupling unit subsequently receives the voltage test signal after it has propagated along the channel, then the received signal can be processed (e.g. analysed), e.g. by the voltage signal producing and/or processing apparatus, so as to determine the physical condition or state of the channel using standard techniques, e.g. so as to ensure that data signals can propagate correctly within twisted pairs in the twisted pair cable or network channel. The voltage test signal might, for example, be a time domain reflectometry signal or a frequency domain reflectometry signal. The standard techniques may be time domain reflectometry or frequency domain reflectometry.

It should be appreciated that this is not the only way in which the physical condition or state of one or more channels within a network can be determined. Other methods and apparatuses for determining the physical condition or state of channels within a network are disclosed, for example, in UK patent applications GB0905361.2 and GB1018582.5, also by the present inventors.

The or each coupling unit may be configured to be installed in a patch panel, e.g. having suitable lugs, bevels and/or retaining clips for this purpose. Preferably, the or each coupling unit is installed in a patch panel. For the avoidance of any doubt, if there are a plurality of coupling units, the coupling units could be installed in different patch panels, i.e. the coupling units need not all be installed in the same patch panel. The patch panel may form part of a local area network. Typically, a patch panel will have a front side having network ports into which shorter "patch" (twisted pair) cables are plugged and a back side into which longer, more permanent, "fixed" (twisted pair) cables are plugged.

Preferably, the or each coupling unit is configured so that its conductive elements become electrically connected to a twisted pair cable if the twisted pair cable is installed in the network port with which the coupling unit is associated.

The or each coupling unit could form an integral part of one or more patch panels. Accordingly, the monitoring apparatus could include one or more patch panels, each patch panel including one or more coupling units that form an integral part of the patch panel. Components of the voltage signal producing andtor processing apparatus may also be included in one or more patch panels.

Alternatively the or each coupling unit may be configured to be retrofitted to an existing patch panel. The first aspect of the invention may provide a method of retrofitting a coupling unit as described herein to a patch panel.

Many different possible "retrofit" possibilities can be envisaged. For example, each coupling unit (which could have two socket interfaces, for example) could be configured to be connected to a respective network port at the back of a patch panel such that connecting a twisted pair cable to the network port is achieved by plugging the twisted pair cable into the coupling unit. As another example, each coupling unit could have a respective first interface (which could be a plug interface) and a respective second interface (which could be a socket interface), wherein the first interface is configured to plug into a respective network port at the front of the patch panel such that connecting a twisted pair cable to the network port is achieved by plugging the twisted pair cable into a second interface of the coupling unit. Here, any above described connectors of the coupling unit could be led to a voltage signal producing and/or processing apparatus at the back of the patch panel. As another example, the coupling units and voltage signal producing and/or processing apparatus may be located in a common enclosure (e.g. twenty-four of them) with the whole assembly being configured to plug into the front of the patch panel.

The network monitoring apparatus could, for example, be an apparatus as disclosed in UK patent application

GB1018582.5 (from which published application WO2012/059722 claims priority). This patent application discloses various apparatuses for identifying interconnections in a network comprising a plurality of channels ("cable lines") and/or for determining the physical state of channels ("cable lines") in the network. Coupling units as described herein are preferably configured to be used as direct replacements for the coupling units described in UK patent application GB1018582.5 (from which published application WO2012/059722 claims priority), e.g. serving substantially the same electrical function, preferably so as to permit the apparatuses described in that patent application to be used with shielded twisted pair cables.

The first aspect may also provide a kit of parts for forming a monitoring apparatus as described above. For example, the first aspect of the invention may provide:

a kit of parts for forming a network monitoring apparatus, the kit of parts having: one or more of the coupling units, the or each coupling unit being configured to be associated with a respective network port in a network; and

a voltage signal producing and/or processing apparatus, wherein the voltage signal producing and/or processing apparatus is configured to produce a voltage signal and to convey the voltage signal to at least one electrode of one or more of the coupling units and/or to process a voltage signal conveyed from at least one electrode of one or more of the coupling units.

The first aspect may also provide a method of using a coupling unit described above to transmit and/or receive a voltage signal.

Accordingly, the first aspect of the invention may provide:

a method of using a coupling unit to transmit and/or receive a voltage signal, wherein the method includes: physically connecting the coupling unit to a twisted pair cable using an interface of the coupling unit so that each of a plurality of conductive elements of the coupling unit become electrically connected to a respected conductor of the twisted pair cable; and

using at least one electrode that is adjacent to one or more conductive elements of the coupling unit to transmit a voltage signal to the one or more conductive elements and/or to receive a voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

The method may include any method step implementing or corresponding to any apparatus feature described in connection with the first aspect of the invention.

A second aspect of the invention may provide a method of converting a coupling unit into a coupling unit according to the first aspect of the invention.

Accordingly, the second aspect of the invention may provide:

a method of converting a coupling unit having:

a plurality of conductive elements, each conductive element being configured to be electrically connected to a respective conductor of a twisted pair cable, if the coupling unit is physically connected to the twisted pair cable by the interface;

wherein the method includes.

adding at least one electrode to the coupling unit that is adjacent to one or more conductive elements of the coupling unit, the at least one electrode being configured to transmit a voltage signal to the one or more conductive elements and/or to receive a voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

The coupling unit (before conversion) may, for example, be a typical shielded socket, e.g. similar to that shown in Fig. 26.

The adding at least one electrode may include inserting the at least one electrode into a (respective) space in the coupling unit, e.g. between a plastic inner body and a metal shell of the coupling unit, e.g. between a plastic inner body and rear metal covers of a metal shell of the coupling unit.

The at least one electrode may be located (preferably printed) on a flexible circuit board.

The invention also includes any combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. The apparatuses and methods described above may be used in conjunction with the apparatuses and methods taught in GB0905361.2, GB1009184.1 and GB1018582.5, also by the present inventors.

Herein, "approximately equal" preferably means equal to the extent that there is a percentage difference (or "error") of no more than 50%, 40%, 30%, 20%, 10%, 5%, 2% or 1%.

Fig. 16 shows a typical patch system organised into a server row, a cross-connect row and a network row.

Fig. 17 shows an example of a typical patch panel viewed from an edge of the casing of a patch panel.

Fig. 18 is an internal view of a coupling unit for use with a twisted pair cable, showing the internal components of the coupling unit.

Fig. 19 shows an example layout for the first and second transmitter electrodes of the coupling unit shown in Fig. 18.

Fig. 20 is an external view of the coupling unit shown in Fig. 18, showing the external form of the coupling unit.

Fig. 21 shows a possible deployment of the coupling unit shown in Fig. 18 in a network monitoring apparatus.

Figs. 22(a)-(c) show the possible use of flexible circuit board for one or more electrodes of the coupling unit.

Fig. 23 is an internal view of another coupling unit for use with a twisted pair cable, showing the internal components of the coupling unit.

Fig. 24 shows an example layout for the transmitter electrode of the coupling unit shown in Fig. 23.

Fig. 25 is an external view of the coupling unit shown in Fig. 8, showing the external form of the coupling unit.

Fig. 26 shows the construction of a typical shielded socket for use with a shielded twisted pair cable.

Fig. 27 shows a test coupling unit that was constructed for experimental use in a test apparatus.

Fig. 28 shows a test apparatus incorporating two of the test coupling units shown in Fig. 27.

Figs. 29(a) and (b) shows sample results produced using the test apparatus of Fig. 28.

In general, the following discussion describes embodiments of our proposals that have been devised in light of the above considerations and, in particular, a problem of how to allow voltage signals to be coupled into shielded twisted pair cables by non-contact (preferably capacitive) coupling.

In some embodiments, a coupling unit may be provided e.g. in the form of a monitoring insert which may contain transmitter electrodes and/or receiver electrodes or transceiver electrodes. The coupling unit could, for example, be slatted into a network, positioned for instance at a patch panel interface and could, for example, make use of standard plug and socket connections such as those based on the standard J45 connector. Preferably, the coupling unit is designed so that it does not compromise the data transfer properties of the network, e.g. so as to have little or no effect on the performance of the system. The electrodes are preferably positioned underneath electromagnetic shielding so as to couple with the conductors of shielded twisted pair cables in the network. The coupling unit may be used in a network monitoring apparatus and is preferably able to operate, in essence, in parallel with a host network.

The coupling unit could, for example, be used to exploit the apparatuses and methods disclosed in UK patent applications GB0905361.2, GB1009184.1 and GB1018582.5, also by the present inventors.

The coupling unit can also be used in an installation procedure for a network monitoring apparatus such that the monitoring system can be easily fitted onto an operation host network. The functionality of software underpinning the network monitoring apparatus may, for example, be as disclosed in GB1018582.5 (from which published application WO2012/059722 claims priority). Fig. 18 is an internal view of a coupling unit 100 for use with a twisted pair cable, showing the internal components of the coupling unit 00.

The coupling unit 100 is preferably for use in a network monitoring apparatus, e.g. as described below, and may therefore be referred to as a "monitoring insert".

The coupling unit 100 preferably has a first interface 102 for physically connecting the coupling unit 100 to a first twisted pair cable (not shown) and a second interface 104 for physically connecting the coupling unit to a second twisted pair cable (not shown). Preferably, the first interface 102 is a plug interface and the second interface 104 is a socket interface. The plug and socket interfaces 102, 104 may conform to a standard for twisted pair cables, e.g. RJ45, e.g. so that the coupling unit can be fitted at a node on a local area network, e.g. at a patch panel, e.g. as shown in Fig. 21 which is described below.

In Fig. 18, the coupling unit 100 is shown with the first (plug) interface 102 at one end and the second (socket) interface 104 at the other, but other arrangements are possible.

The coupling unit preferably has a housing 110, e.g. including a plastic inner body surrounded by a metal shell. The housing 110 preferably houses components of the coupling unit, e.g. the electrodes and conductive elements described below. The housing 110 preferably includes mechanical elements, e.g. lugs, bevels, and/or retaining clips (not shown), for attaching the coupling unit 100 to a patch panel, e.g. as a physical replacement to an existing RJ-45 type socket.

The coupling unit 100 preferably has a plurality of (in this example eight) conductive elements 120, preferably grouped in pairs 120a, 120b, 120c, 120d. Each pair of conductive elements 120a, 120b, 120c, 120d of the coupling unit is preferably configured to be electrically connected to both (e.g. forward and return) conductors of a respective twisted pair of a first twisted pair cable and to both (e.g. forward and return) conductors of a respective twisted pair of a second twisted pair cable if the coupling unit is physically connected to the first twisted pair cable by the first (plug) interface 102 and to the second twisted pair cable by the second (socket) interface 104. This may, for example, be achieved by respective electrical contacts 122, 124 being suitably positioned at either end of each conductive element 120. Fig. 18 shows the pairs of conductive elements 120a, 120b, 120c, 120d as being connected point to point between respective electrical contacts 122, 124 on the first (plug) and second (socket) interfaces 102, 104.

The coupling unit 100 is preferably designed to ensure that the integrity of transmission of data within the pairs of conductive elements 120a, 120b, 120c, 120d is not compromised. For instance the characteristic impedance of channels (or "data lines") within twisted pair cables to which the coupling unit may be physically connected, typically 100 Ohm, would preferably be maintained through the coupling unit 100.

The coupling unit 100 preferably has a first transmitter electrode 130a that is adjacent to the first pair of conductive elements 120a of the coupling unit and a second transmitter electrode 30b that is adjacent to the second pair of conductive elements 120b of the coupling unit 100. Preferably, the first transmitter electrode 130a and the second transmitter electrode 130b are configured to transmit a differential voltage signal to the first and second pairs of conductive elements 120a, 120b by non-contact (capacitive) coupling with the first and second pairs of conductive elements 120a, 120b, preferably so that, if the coupling unit 100 is physically connected to a twisted pair cable by the first or second interface 102, 104, the differential voltage signal propagates along the twisted pair cable between the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 120a and the twisted pair of the twisted pair cable electrically connected to the second pair of conductive elements 120b.

The coupling unit 100 preferably has a first receiver electrode 132a that is adjacent to the first pair of conductive elements 120a of the coupling unit and a second receiver electrode 132b that is adjacent to the second pair of conductive elements 120b of the coupling unit 100. Preferably, the first receiver electrode 132a and the second receiver electrode 132b are configured to receive a differential voltage signal from the first and second pairs of conductive elements 120a, 120b by non-contact (capacitive) coupling with the first and second pairs of conductive elements 120a, 120b, preferably so that, if the coupling unit 100 is physically connected to a twisted pair cable by the first or second interface 102, 104, the differential voltage signal is received after it has propagated along the twisted pair cable between the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 120a and the twisted pair of the twisted pair cable electrically connected to the second pair of conductive elements 120b.

Each electrode 130a, 130b, 132a, 132b of the coupling unit 100 may be provided in the form of a respective plate. Each plate may be made of, for example, foil, e.g. copper foil. Preferably, each plate has an area of 10mm² or larger. More preferably, each plate has an area 20mm² or larger, more preferably an area that is approximately equal to 20mm².

The coupling unit 100 shown in Fig. 18 may be referred to as a "transceiver" coupling unit, as it is preferably configured to both transmit a voltage signal to, and receive a voltage signal from, a twisted pair cable in the manner described above. However, "transmitter" coupling units (configured only to transmit a voltage signal to a twisted pair cable, e.g. having only transmitter electrodes 130a, 130b) and "receiver" coupling units (configured only to receive a voltage signal from a twisted pair cable, e.g. having only receiver electrodes 132a, 132b) are also envisaged.

The coupling unit 100 preferably includes electromagnetic shielding 140a, 140b, preferably of a conductive material. In particular, the coupling unit preferably includes electromagnetic shielding 140a arranged to shield the first electrodes 130a, 132a from the second electrodes 130b, 132b, electromagnetic shielding 140a arranged to shield the first pair of conductive elements 120a from the second pair of conductive elements 120b (more preferably arranged to shield each pair of conductive elements from the other pairs of conductive elements), and/or electromagnetic shielding 140b arranged to shield the transmitter electrodes 130a, 130b from the receiver electrodes 132a, 132b.

The electromagnetic shielding 140a, 140b is preferably configured to electrically connect to electromagnetic shielding of a shielded twisted pair cable (not shown), if the coupling unit 100 is physically connected to the shielded twisted pair cable by the first or second interface 102, 104.

It should be appreciated that Fig. 18 is diagrammatical and has the purpose of illustrating what internal components are included in the coupling unit 100. Fig. 18 does not necessarily show the actual layout of the internal components of the coupling unit 100.

Fig. 19 shows an example layout for the first and second transmitter electrodes 130a, 130b of the coupling unit 100 shown in Fig. 18.

The symbols and "-" shown in the conductive elements 120 in Fig. 19 respectively indicate "forward" and "return" conductive elements 120, e.g. which are respectively to be connected to the toward and return conductors of a twisted pair in a twisted pair cable.

As shown in Fig. 19, a first voltage signal +V of a differential voltage signal is conveyed to the first transmitter electrode 130a, with a second, complimentary, voltage signal -V of the differential voltage signal being conveyed to the second transmitter electrode 130b. Here, the electromagnetic shielding 140a, 140b of the coupling unit is connected to a local ground and may be viewed as being at 0V relative to the differential voltage signal. In use, an electric field is produced between the first transmitter electrode 130a and the first pair of conductive elements 120a, so as to couple the first voltage signal +V of the differential voltage signal to the first pair of conductive elements 0a. Similarly, in use, an electric field is produced between the second transmitter electrode 30b and the second pair of conductive elements 120b, so as to couple the second voltage signal -V of the differential voltage signal to the second pair of conductive elements 120b. In this way, the first transmitter electrode 130a and the second transmitter electrode 130b are able to transmit a differential voltage signal to the first and second pairs of conductive elements 120a, 120b by non-contact (capacitive) coupling with the first and second pairs of conductive elements 120a, 120b, so that, if the coupling unit 100 is physically connected to a twisted pair cable by the first or second interface 102, 04, the differential voltage signal can propagate along the twisted pair cable between the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 120a and the twisted pair of the twisted pair cable electrically connected to the second pair of conductive elements 120b. Here, electromagnetic shielding of the twisted pair cable may act as a return path for the first and second voltage signals of the differential voltage signal (these two voltage signals will generally cancel each other out on the return path).

The same layout of electrodes can also be used for the first and second receiver electrodes 132a, 132b, with the first receiver electrode 132a replacing the first transmitter electrode 130a and with the second receiver electrode 132b replacing the second transmitter electrode 130b. In use, a first voltage signal +V of a differential voltage signal can be received from the first pair of conductive elements 120a by the first receiver electrode 132a as a result of an electric field produced between the first pair of conductive elements 120a and the first receiver electrode 32a. Similarly, in use, a second voltage signal -V of a differential voltage signal can be received from the second pair of conductive elements 120b by the second receiver electrode 132b as a result of an electric field produced between the second pair of conductive elements 120b and the second receiver electrode 132b. In this way, the first receiver electrode and the second receiver electrode are able to receive a differential voltage signal from the first and second pairs of conductive elements 120a, 120b by non-contact (capac/tive) coupling with the first and second pairs of conductive elements 120a, 120b, so that, if the coupling unit is physically connected to a twisted pair cable by the first or second interface, the differential voltage signal can be received after it has propagated along the twisted pair cable between the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 120a and the twisted pair of the twisted pair cable electrically connected to the second pair of conductive elements 20b.

Fig. 20 is an external view of the coupling unit 100 shown in Fig. 18, showing the external form of the coupling unit 100.

The coupling unit 100 preferably includes a first connector 150 for conveying a differential voltage signal produced by a voltage signal producing and/or processing apparatus (not shown) to the first and second transmitter electrodes 130a, 130b of the coupling unit 100. The coupling unit 100 preferably includes a second connector 152 for conveying a differential voltage signal received by the first and second receiver electrodes 132a, 132b of the coupling unit 100 to a voltage signal producing and/or processing apparatus. The connectors 150, 152 could also be for coupling the shielding of the coupling unit 200 to a local ground.

Each connector may 150, 152, for example, take the form of a twisted pair cable (shielded or unshielded) or a coaxial cable. In any case, the connectors are preferably designed to ensure that any coupling between the connectors (or between the conductors within the connectors) is small or negligible compared with the coupling between the electrodes 130a, 130b, 132a, 132b and the first and second pairs of conductive elements 120a, 120b.

Fig. 6 shows a possible deployment of the coupling unit 100 shown in Fig. 3 in a network monitoring apparatus 160.

The network monitoring apparatus 160 preferably has one or more of the coupling units 00, the or each coupling unit 100 preferably being associated or configured to be associated with a respective network port in a network, and a voltage signal producing and/or processing apparatus 170, wherein the voltage signal producing and/or processing apparatus 170 is preferably configured to produce a differential voltage signal and to convey the differential voltage signal to the first and second transmitter electrodes of one or more of the coupling units 100 and/or to process a voltage signal conveyed from the first and second receiver electrodes of one or more of the coupling units 100.

For clarity, only one coupling unit 100a is illustrated in Fig. 21 , but it should be apparent that many other coupling units 100 are preferably included.

Preferably, the coupling units 100 are installed in (e.g. a respective channel of) a patch panel 180 of a local area network with each coupling unit 100 being associated with a respective network port of the patch panel 180. Preferably, each coupling unit 100 is configured so that its conductive elements 120 become electrically connected to a twisted pair cable if the twisted pair cable is installed in the network port with which the coupling unit 100 is associated.

The coupling unit 100a illustrated in Fig. 21 is shown as being installed internally within the patch panel 180, connected to (and located between) a socket 182a of a fixed cable 182 within the patch panel 180 and a plug 184a of an external patch cable 184, with its first and second connectors 150, 152 being connected to the voltage signal producing and/or processing apparatus 170. Naturally, the patch cable 184 may or may not be present depending on the usage of the particular network port on the patch panel.

Of course, alternative variants of the arrangement shown in Fig. 21 can be envisaged.

For example, the one or more coupling units 100 could form an integral part of one or more patch panels. Accordingly, the network monitoring apparatus 160 could include one or more patch panels, each patch panel including one or more coupling units 100 that form an integral part of the patch panel. Components of the voltage signal producing and/or processing apparatus 1 0 may also be included in one or more patch panels.

As another example, the one or more coupling units 100 could be configured to fit to the front of the patch panel 180, rather than internally within the patch panel.

As another example, the plurality of coupling units may be configured to be retrofitted to existing patch panels. Many different possible "retrofit" possibilities can be envisaged and some such possibilities have already been discussed above.

Preferably, the voltage signal producing and/or processing apparatus 170 is configured to produce a differential voltage signal and to convey the differential voltage signal to the first transmitter electrode 130a and the second transmitter electrode 130b of a coupling unit 100.

The voltage signal producing and/or processing apparatus 170 could, for example, be configured to produce a differential voltage signal and convey it to the first and second transmitter electrodes 30a, 130b of a coupling unit 100 using an arrangement similar to that disclosed in UK patent applications GB090536 .2, also by the present inventors, e.g. using a voltage signal generator configured to produce a single-ended voltage signal and an electrical isolation means (e.g. a balun) configured to convert the single-ended voltage signal into a differential voltage signal before it is conveyed to the first and second transmitter electrodes 130a, 130b.

Preferably, the voltage signal producing and/or processing apparatus 170 is configured to process a differential voltage signal conveyed from the first receiver electrode 132a and the second receiver electrode 132b of a coupling unit 100.

The voltage signal producing and/or processing apparatus 170 could, for example, be configured to process a differential voltage signal conveyed from the first receiver electrode 132a and the second receiver electrode 132b of a coupling unit 00 using an arrangement similar to that disclosed in UK patent applications GB0905361.2, also by the present inventors, e.g. using an electrical isolation means to convert the differential voltage signal into a single-ended voltage signal and a voltage signal processor configured to process the single-ended voltage signal.

The network monitoring apparatus 160 may be configured to monitor the network, for example, by identifying one or more interconnections between network ports within a network (e.g. to produce a connection map of path leads) and/or by determining the physical condition or state of one or more channels within the network.

Configuring the network monitoring apparatus 160 to monitor a network by identifying one or more interconnections between network ports within a network may be achieved, for example, by the voltage signal producing and/or processing apparatus 170 being configured to produce a voltage test signal and to convey the voltage test signal to the first and second transmitter electrodes 130a, 130b of one of the coupling units 100, so that the first and second transmitter electrodes 130a, 130b of the coupling unit 100 transmit the voltage test signal. If another coupling unit 100 subsequently receives the voltage test signal, then an interconnection between the coupling unit 100 that transmitted the voltage test signal and the coupling unit 100 that received the voltage test signal can be identified, and therefore an interconnection between the network ports with which those coupling units 100 are associated can be identified.

It should be appreciated that this is not the only way in which interconnections between network ports can be identified. Other methods and apparatuses for identifying interconnections between coupling units are disclosed, for example, in UK patent applications GB0905361.2, GB1009184.1 and GB1018582.5, also by the present inventors. Configuring the network monitoring apparatus 160 to monitor the network by determining the physical condition or state of one or more channels within the network may be achieved, for example, by the voltage signal producing and/or processing apparatus 170 being configured to produce a voltage test signal and to convey the voltage test signal to the first and second transmitter electrodes 130a, 130b of one of the coupling units 100, so that the first and second transmitter electrodes 130a, 130b of the coupling unit 00 transmits the voltage test signal so that it propagates along a channel to which it is connected. If the same (or another) coupling unit 100 subsequently receives the voltage test signal after it has propagated along the channel, then the received signal can be processed (e.g. analysed), e.g. by the voltage signal producing and/or processing apparatus 70, so as to determine the physical condition or state of the channel using standard techniques, e.g. so as to ensure that data signals can propagate correctly within twisted pairs in the twisted pair cable or network channel. The voltage test signal might, for example, be a time domain reflectometry signal or a frequency domain reflectometry signal. The standard techniques may be time domain reflectometry or frequency domain reflectometry.

The network monitoring apparatus 160 could, for example, be an apparatus as disclosed in UK patent application GB1018582.5 (from which published application O2012/059722 claims priority). This patent application discloses various apparatuses for identifying interconnections in a network comprising a plurality of channels ("cable lines") and/or for determining the physical state of channels ("cable lines") in the network. Coupling units 100 as described herein are preferably configured to be used as direct replacements for the coupling units described in UK patent application GB1018582.5 (from which published application WO2012/059722 claims priority), e.g. serving substantially the same electrical function, preferably so as to permit the apparatuses described in that patent application to be used with shielded twisted pair cables.

Fig. 22(a) is a perspective view. Fig. 22(b) show the view from the electrode ("plate") side and Fig. 22(c) is an illustration of the view from the ground plane side.

As shown in Figs. 22(a)-(c),-a pair of electrodes (e.g. plates) of the coupling unit 100, e.g. the transmitter electrodes 130a, 130b or the receiver electrodes 132a, 132b, may be located (preferably printed) on a flexible circuit board 134, e.g. of a suitable material such as polyimide. A ground plane 36 may be located (preferably printed) on an opposite side of the flexible circuit board 134 to the electrodes 130a/132a, 130b/132b. The ground plane 136 may serve a useful electromagnetic screening/shielding role for the electrodes 130a 132a, 130b/132b and, if the coupling unit has electromagnetic shielding 140a, 140b, the ground plane may form part of the electromagnetic shielding 140a, 140b.

Figs. 22(a)-(c) thereby highlights the use of flexible printed board (PCB) material such as polyimide or similar substrate material as a convenient and inexpensive means of realising a pair of transmitter electrodes 130a, 130b or receiver electrodes 132a, 132b for the coupling unit 100.

In summary, the electrodes of the coupling unit shown in Fig. 18 are able to couple capacitively to selected channels (or "data lines") such that voltage test signals (or "monitoring signals") can be applied to the network in a similar manner to that described in UK patent application GB0905361.2, also by the present inventors. Capacitive coupling may be achieved through the dielectric insulation surrounding the data lines. In addition, internal shielding or screening is typically included to reduce direct coupling between the transmitter and receiver electrodes (or "plates") and unwanted coupling between the electrodes (or "plates") and non-selected data lines depending on the routing of the conductive elements (or "connecting tracks") to the transmitter and receiver electrodes (or "plates").

Alternative embodiments of the coupling unit are envisaged. For example, a pair of electrodes forming a small value coupling capacitor (e.g. having a capacitance of the order of 1 pF) could be used (instead of individual electrodes) to achieve the non-contact (capacitive) coupling function previously achieved by individual electrodes.

As another example, instead of first and second transmitter electrodes 130a, 130b and first and second receiver electrodes 132a, 132b, the coupling unit 100 may instead include first and second transceiver electrodes, wherein first transceiver electrode and the second transceiver electrode are configured to transmit a differential voltage signal to the first and second conductive elements 120a, 120b by non-contact coupling with the first and second conductive elements 120a, 120b and to receive a differential voltage signal from the first and second conductive elements 120a, 120b by non- contact coupling with the first and second conductive elements 120a, 120b. Configuring a transceiver electrode to both transmit and receive a voltage signal may be achieved, for example, using a directional coupler, which component is well Known e.g. in the art of radio technology.

As another example, instead of the electrode arrangement shown in Fig. 20 for transmitting and/or receiving a differential voltage signal, an electrode arrangement for transmitting and/or receiving a single-ended voltage signal is also possible, e.g. with a single electrode being used to transmit and/or receive a single-ended voltage signal to conductive elements (data lines). Here, shielding of a twisted pair cable may act as a return path for the single-ended voltage signal. A coupling unit including such an electrode arrangement is shown in Fig. 23 and discussed below.

Fig. 23 is an internal view of another coupling unit 200 for use with a twisted pair cable, showing the internal components of the coupling unit 200.

The coupling unit 200 shown in Fig. 23 has many features which are the same as the coupling unit 100 shown in Fig. 18. Alike features have been given corresponding reference numerals and need not be described in further detail.

The coupling unit 200 preferably has a transmitter electrode 230 (which may be a solitary transmitter electrode) that is adjacent to the first pair of conductive elements 220a of the coupling unit, the transmitter electrode 230 being configured to transmit a single-ended voltage signal to the first pair of conductive elements 220a by non-contact (capacitive) coupling with the pair of conductive elements 220a, preferably so that, if the coupling unit 200 is physically connected to a twisted pair cable by the first or second interface 202, 204, the single-ended voltage signal propagates along the twisted pair cable via the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 220a. Here, electromagnetic shielding of the twisted pair cable may act as a return path for the single-ended voltage signal.

The coupling unit preferably has a receiver electrode 232 (which may be a solitary receiver electrode) that is adjacent to the first pair of conductive elements 220a, the receiver electrode 232 being configured to receive a single-ended voltage signal from the first pair of conductive elements 220a by non-contact (capacitive) coupling with the first pair of conductive elements 220a, preferably so that, if the coupling unit 200 is physically connected to a twisted pair cable by the interface, the single-ended voltage signal is received after it has propagated along the twisted pair cable via the twisted pair of the twisted pair cable electrically connected to the first pair of conductive elements 220a.

The coupling unit 200 may have electromagnetic shielding 240a, 240b similar to that described in connection with the coupling unit 100 shown in Fig. 18.

Fig. 24 shows an example layout for the transmitter electrode 230 of the coupling unit 200 shown in Fig. 23.

As shown in Fig. 24, a single-ended voltage signal V is conveyed to the transmitter electrode 230. Here, the electromagnetic shielding 240a, 240b of the coupling unit 200 is preferably connected to a local ground and may be viewed as being at 0V relative to the single-ended voltage signal. In use, an electric field is produced between the transmitter electrode 230 and the first pair of conductive elements 220a, so as to couple the single-ended voltage signal to the first pair of conductive elements 220a. The same electrode layout can also be used for the receiver electrode 232, i.e. with the receiver electrode 230 taking the place of the transmitter electrode 230. In use, a single-ended voltage signal V can be received from the first pair of conductive elements 220a as a result of an electric field produced between the pair of conductive elements 220a and the receiver electrode 232.

Fig. 25 is an external view of the coupling unit 200 shown in Fig. 23, showing the external form of the coupling unit 200.

As shown in Fig. 25, the coupling unit 200 preferably includes a connector 250 for conveying a single-ended voltage signal produced by a voltage signal producing and/or processing apparatus to the transmitter electrode 230 of the coupling unit 200, and for conveying a single-ended voltage signal received by the receiver electrode 232 of the coupling unit 200 to a voltage signal producing and/or processing apparatus. The connector 250 could also be for coupling the shielding of the coupling unit 200 to a local ground.

The connector 250 may, for example, take the form of a twisted pair cable (shielded or unshielded) or a coaxial cable.

The coupling unit shown in Fig. 23 may be deployed in a similar fashion to that shown in Fig. 18, except that a single- ended voltage signal, rather than a differential voltage signal may be produced and/or processed by a voltage signal producing and/or processing apparatus.

Fig. 26 shows the construction of a typical shielded (e.g. RJ45-type) socket 300 for use with a shielded twisted pair cable, e.g. for use with a STP or F/UTP cable.

A housing of the shielded socket 300 includes a plastic inner body 310 surrounded by a metal shell 320. The metal shell 320provides electromagnetic shielding for the shielded socket 300. A cable 330 is connected to the shielded socket using insulated displacement connection (IDC) type terminals 312 contained in the plastic inner body 310. The IDC terminals are typically enclosed by rear metal covers 320a, 320b of the metal shell 320 which are removable to allow the cable 330 to be fitted and yet maintain screening integrity and clamp the cable 330 in place once the shielded socket 300 is assembled. On some shielded sockets there are spaces between the plastic inner body 310 containing the IDC terminals 312 and the rear metal covers 320a, 320b of the metal shell 320. These spaces may be able to accommodate an electrode, e.g. printed on a flexible circuit board.

Accordingly, a conventional coupling unit, e.g. a shielded socket 300 as shown in Fig. 26, could be converted into a coupling unit according to the invention, e.g. by inserting at least one electrode, e.g. printed on a flexible circuit board, into a (respective) space between a plastic inner body 310 containing IDC terminals 312 and rear metal covers 320a, 320b of a metal shell 320.

Example

Fig. 27 shows a test coupling unit 400 that was constructed for experimental use in a test apparatus described below.

The test coupling unit 400 was made by converting a typical shielded socket 404 similar to that shown in Fig. 26, and a typical shielded plug 402, the shielded socket 404 and shielded plug 402 being joined to each other by a short length of shielded twisted pair cable 406. Here, the shielded plug 402 acts as a first interface of the test coupling unit 400 and the shielded socket 404 acts as a second interface of the test coupling unit 400.

Two electrodes, made using a flexible PCB similar to that shown in Fig. 22, were added by inserting the electrodes into respective spaces between an inner plastic body and a metal shell in the shielded socket, such that a first electrode was adjacent to a first pair of conductive elements within the socket and a second electrode was adjacent to a second pair of conductive elements within the socket. The test unit also includes a connector 450 (twisted pair cable) for connecting the two electrodes of the coupling unit to a voltage signal producing and/or processing apparatus.

Fig. 28 shows a test apparatus 460 incorporating two of the test coupling units 400 shown in Fig. 27.

In the test apparatus 460, two of the test coupling units 400 described with reference to Fig. 27 are connected in line, with a first test coupling unit 400a acting as a transmitter coupling unit and a second test coupling unit 400b acting as a receiver. The connectors 450a, 450b of the test coupling units 400a, 400b are connected to a voltage signal producing and/or processing apparatus 470 which in this case includes a vector network analyser (VNA) with a frequency range from 1 MHz to 500 MHz with matching baluns for single-ended to differential voltage signal conversion.

It should be appreciated that although Fig. 28 shows the voltage signal producing and/or processing apparatus 470 as a vector network analyser for experimental purposes, the test coupling units 400a, 400b could instead be connected to the voltage signal producing and/or processing apparatus of a network monitoring apparatus, e.g. configured to identify interconnections between network ports within a network (e.g. to produce a connection map of path leads) and/or to determine the physical condition or state of channels within the network, e.g. an apparatus as described in GB1018582.5 (from which published application WO2012/059722 claims priority).

The test apparatus 460 shows the transmitter test coupling unit 400a as being connected to an unterminated 2 m STP cable 480a and the receiver test coupling unit 400b as being connected (by a conventional coupling unit 481 such as that shown in Fig. 26) to a 24 m STP cable 480b. As shown in Fig. 27, an extra 2 m STP fly lead 482 is connected to a distal end of the 24 m STP cable 480b.

The sample results shown in Figs. 29(a) and (b) were both produced by performing time domain reflectometry using the vector network analyser 470 to produce and process differential voltage signals and convey those signals to and from the electrodes of the transmitter test coupling unit 400a and the receiver coupling unit 400b respectively.

Fig. 29(a) shows the results obtained when the 24 m STP cable 480a was left unconnected at its distal end, i.e. with the extra 2 m STP fly lead 482 removed. Note that Fig. 29(a) incorrectly shows the length of the 24 m STP cable 480a as 27 m due to signal delays in the vector network analyser 470, which could be removed by calibration of the test apparatus 460 and are not of significance here.

Fig 29(b) shows the results obtained when the extra 2 m STP fly lead 482 was connected to the distal end of the 24 m STP cable 480a. Fig. 29(b) therefore shows the change caused by the addition of the extra 2 m fly lead 482 and indicates that the overall length of the channel has increased by 2 m on the trace.

These sample results show the ability of the test coupling units 400a, 400b to transmit and receive a differential voltage signal and further demonstrate that the ability of the test coupling units 400a, 400b to be used as part of a network monitoring apparatus performing reflectometry.

When used in this specification and claims, the terms "comprises", "comprising", "including", "has" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or integers.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

STATEMENTS:

A. A coupling unit for use with a twisted pair cable, the coupling unit having:

an interface for physically connecting the coupling unit to a twisted pair cable; a plurality of conductive elements, each conductive element being configured to be electrically connected to a respective conductor of a twisted pair cable, if the coupling unit is physically connected to the twisted pair cable by the interface; and

B. A coupling unit according to statement A, wherein the coupling unit has:

at least one first electrode that is adjacent to one or more first conductive elements of the coupling unit; and at least one second electrode that is adjacent to one or more second conductive elements of the coupling unit; wherein the at least one first electrode and the at least one second electrode are configured to transmit a differential voltage signal to the first and second conductive elements by non-contact coupling with the first and second conductive elements and/or to receive a differential voltage signal from the first and second conductive elements by non- contact coupling with the first and second conductive elements.

C. A coupling unit according to statement B, wherein the coupling unit includes electromagnetic shielding arranged to shield the at least one first electrode from the at least one second electrode and/or electromagnetic shielding arranged to shield the one or more first conductive elements from the one or more second conductive elements.

D. A coupling unit according to statement B or C wherein the coupling unit has.

E. A coupling unit according to any one of statements B to D wherein the coupling unit has:

wherein the at least one first receiver electrode and the at least one second receiver electrode are configured to receive a differential voltage signal from the first and second conductive elements by non-contact coupling with the first and second conductive elements.

F. A coupling unit according to statement B or C wherein the coupling unit has:

at least one first transceiver electrode that is adjacent to the one or more first conductive elements of the coupling unit; ^"and

at least one second transceiver electrode that is adjacent to the one or more second conductive elements of the coupling unit;

G. A coupling unit according to statement A wherein the at least one electrode adjacent to the one or more conductive elements is configured to transmit a single-ended voltage signal to the one or more conductive elements by non-contact coupling with the one or more conductive elements and/or to receive a single-ended voltage signal from the one or more conductive elements by non-contact coupling with the one or more conductive elements.

H. A coupling unit according to statement G wherein the coupling unit has:

at least one transmitter electrode adjacent to one or more conductive elements, the at least one transmitter electrode being configured to transmit a single-ended voltage signal to the one or more conductive elements by non- contact coupling with the one or more conductive elements.

I. A coupling unit according to statement G or H wherein the coupling unit has.

J. A coupling unit according to statement G wherein the coupling unit has:

K. A coupling unit according to any one of the previous statements wherein the twisted pair cable is a shielded twisted pair cable including electromagnetic shielding.

L. A coupling unit according to any one of the previous statements wherein the coupling unit includes electromagnetic shielding including any one or more of.

electromagnetic shielding arranged to shield at least one first electrode from at least one second electrode, electromagnetic shielding arranged to shield one or more first conductive elements from one or more second conductive elements;

electromagnetic shielding arranged to shield at least one transmitter electrode from at least one receiver electrode; and/or

electromagnetic shielding arranged to shield the conductive elements from external electromagnetic interference for the coupling unit and/or reduce crosstalk between coupling units.

. A coupling unit according to any one of the previous statements wherein the coupling unit includes electromagnetic shielding, and the electromagnetic shielding of the coupling unit is configured to electrically connect to the electromagnetic shielding of a shielded twisted pair cable, if the coupling unit is physically connected to the twisted pair cable by an interface of the coupling unit.

N- A coupling unit according to any one of the previous statements wherein the coupling unit includes electromagnetic shielding, and the electromagnetic shielding of the coupling unit is configured to electrically connect to a local ground.

O. A coupling unit according to any one of the previous statements wherein the coupling unit includes:

a second interface for physically connecting the coupling unit to a second twisted pair cable; wherein each conductive element of the coupling unit is configured to be electrically connected to a respective conductor of a first twisted pair cable and a respective conductor of a second twisted pair cable, if the coupling unit is physically connected to the first twisted pair cable by the first interface and to the second twisted pair cable by the second interface.

P. A coupling unit according to any one of the previous statements wherein:

the conductive elements of the coupling unit are grouped in one or more pairs, with the or each pair of conductive elements being configured to be electrically connected to both conductors of a respective twisted pair of a twisted pair cable, if the twisted pair cable is physically connected to the coupling unit by the interface; and

the or each electrode of the coupling unit is adjacent to one or more pairs of conductive elements of the coupling unit.

Q. A coupling unit according to any one of the previous statements wherein the coupling unit includes:

a plurality of pairs of conductive elements; and

electromagnetic shielding arranged to shield each pair of conductive elements from the other pair(s) of conductive elements.

R. A coupling unit according to any one of the previous statements wherein the or each electrode of the coupling unit is provided in the form of a respective plate having an area of 10 mm² or larger, or 20 mm² or larger.

S. A coupling unit according to any one of the previous statements wherein one or more electrodes of the coupling unit istere printed on one or more flexible circuit boards.

T. A coupling unit according to any one of the previous statements wherein the coupling unit has a housing that houses the or each electrode and the conductive elements.

U. A coupling unit according to statement T, wherein the housing includes a plastic inner body surrounded by a metal shell, with the metal shell providing electromagnetic shielding arranged to shield the conductive elements from external electromagnetic interference and/or reduce crosstalk between coupling units.

V. A coupling unit according to any one of the previous statements wherein the coupling unit includes one or more connectors for conveying a voltage signal produced by a voltage signal producing and/or processing apparatus to at least one electrode of the coupling unit and/or for conveying a voltage signal received by at least one electrode of the coupling unit to a voltage signal producing and/or processing apparatus.

W. An apparatus having:

one or more coupling units according to any one of the previous statements;

a voltage signal producing and/or processing apparatus configured:

to produce a voltage signal and to convey the voltage signal to at least one electrode of the coupling unit; and/or to process a voltage signal conveyed from at least one electrode of the coupling unit.

X. A network monitoring apparatus for monitoring a network, the network monitoring apparatus having:

one or more coupling units according to any one of statements A to V, the or each coupling unit being associated or configured to be associated with a respective network port in a network; and

a voltage signal producing and/or processing apparatus, wherein the voltage signal producing and/or processing apparatus is configured to produce a voltage signal and to convey the voltage signal to at least one electrode of one or more of the coupling units and/or to process a voltage signal conveyed from at least one electrode of one or more of the coupling units. Y. A network monitoring apparatus according to statement X, wherein the network monitoring apparatus is configured to monitor a network by identifying one or more interconnections between network ports within a network andfar by determining the physical condition or state of one or more channels within a network.

Z. A network monitoring apparatus according to statement X or Y, wherein the or each coupling unit is installed in a patch panel of the network.

ZA. A network monitoring apparatus according to any one of statements X to Z wherein the or each coupling unit forms an integral part of a patch panel.

ZB. A network monitoring apparatus according to any one of statements X to Z wherein the or each coupling unit is retrofitted to a patch panel.

ZC. A kit of parts for forming a network monitoring apparatus, the kit of parts having:

one or more coupling units according to any one of statements A to V, the or each coupling unit being configured to be associated with a respective network port in a network; and

ZE. A method of using a coupling unit to transmit and/or receive a voltage signal, wherein the method includes. physically connecting the coupling unit to a twisted pair cable using an interface of the coupling unit so that each of a plurality of conductive elements of the coupling unit become electrically connected to a respected conductor of the twisted pair cable; and

ZF. A method of converting a coupling unit having;

wherein the method includes:

ZG. A coupling unit or apparatus substantially as any one embodiment herein described with reference to and as shown in the accompanying drawings.

ZH. A method substantially as any one embodiment herein described with reference to and as shown in the accompanying drawings.

Claims

CLAIMS:

1. A network monitoring apparatus for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the network monitoring apparatus having:

2. A network monitoring apparatus according to claim 1, wherein the processing apparatus is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of a noise floor of a signal received by the coupling unit.

3. A network monitoring apparatus according to claim 2, wherein the noise floor of a signal received by the coupling unit is calculated as the root mean square value of the signal over a predetermined length of time and/or a predetermined frequency range.

4. A network monitoring apparatus according to claim 2 or 3, wherein the processing apparatus is configured to determine whether one or more data signals are propagating within one or more twisted pairs of the network channel based on an analysis of whether a noise floor of a signal received by the coupling unit exceeds a predetermined threshold.

5. A network monitoring apparatus according to any previous claim, wherein the coupling unit is configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with conductors of the network channel.

6. A network monitoring apparatus according to any previous claim, wherein the network monitoring apparatus includes.

wherein the processing apparatus is configured to:

7. A network monitoring apparatus according to claim 6, wherein the processing apparatus is further configured to determine whether the first port is included in the same network channel as the second port, based on a comparison of one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit with one or more times at which it is determined that one or

^" more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit.

8. A network monitoring apparatus according to claim 6 or 7, wherein the first and second coupling units are each configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel by non-contact coupling with conductors of the network channel.

9. A network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

10. A network monitoring apparatus according to claim 9, wherein the processing apparatus is configured to determine whether the first port is included in the same network channel as the second port based on an identification of common characteristics of a signal received by the first coupling unit and a signal received by the second coupling unit.

11. A network monitoring apparatus according to claim 9 or 10, wherein the processing apparatus is configured to: determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit based on an analysis of a signal received by the first coupling unit;

determine whether one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit based on an analysis of a signal received by the second coupling unit; and determine whether the first port is included in the same network channel as the second port, based on a comparison of one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the first coupling unit with one or more times at which it is determined that one or more data signals are propagating within one or more twisted pairs of the network channel including the second coupling unit.

12. A network monitoring apparatus according to any one of claims 9 to 11 , wherein the processing apparatus is configured to determine whether the first port is included in the same network channel as the second port based on a cross-correlation of a signal received by the first coupling unit and a signal received by the second coupling unit.

13. A network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

14. A network monitoring apparatus according to claim 13, wherein the network monitoring apparatus has:

a first coupling unit associated with a first port included in a network channel of the network, wherein the first coupling unit is configured to couple a first reflectometry signal to the network channel that includes the first port and, if the first reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected first reflectometry signal from the network channel; and a second coupling unit associated with a second port included in a network channel of the network, wherein the second coupling unit is configured to couple a second reflectometry signal to the network channel that includes the second port and, if the second reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the second port, to receive the reflected second reflectometry signal from the network channel;

15. A network monitoring apparatus according to claim 14, wherein the first coupling unit and second coupling unit are configured to operate independently of each other.

16. A network monitoring apparatus according to claim 14 or 15, wherein the analysis of the first and second reflectometry data by the processing apparatus includes comparing the first and second reflectometry data.

17. A network monitoring apparatus according to any one of claims 14 to 16, wherein the processing apparatus is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that a reflected first reflectometry signal received by the first coupling unit has changed compared with a previous reflected first reflectometry signal received by the first coupling unit and/or whether it is determined that a reflected second reflectometry signal received by the second coupling unit has changed compared with a previous reflected second reflectometry signal received by the second coupling unit.

18. A network monitoring apparatus according to any one of claims 14 to 17, wherein the network monitoring apparatus is for identifying and/or mapping interconnections between a plurality of first ports and a plurality of second ports in a network that includes a plurality of network channels, the network monitoring apparatus having:

a plurality of the first coupling units, each first coupling unit being associated with a respective first port included in a respective network channel of the network; and

a plurality of the second coupling units, each second coupling unit being associated with a respective second port included in a respective network channel of the network;

wherein the processing apparatus is configured to produce first reflectometry data representative of reflected first reflectometry signals received by the first coupling units and second reflectometry data representative of reflected second reflectometry signals received by the second coupling units and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the first and second reflectometry data.

19. A network monitoring apparatus according to any one of claims 14 to 18, wherein the network monitoring apparatus has a modulation unit configured to modulate a signal propagating in a network channel of the network, and the analysis of the first and second reflectometry data involves one or more modulations caused by the modulation unit.

20. A network monitoring apparatus according to claim 13, wherein the network monitoring apparatus has:

a modulation unit associated with a second port included in a network channel of the network, wherein the modulation unit is configured to modulate a signal propagating in the network channel that includes the second port; wherein the processing apparatus is configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that involves one or more modulations caused by the modulation unit.

21. A network monitoring apparatus according to claim 20, wherein the processing apparatus is configured to determine whether the first and second ports are included in the same network channel, or are candidates for being included in the same network channel, based on whether it is determined that a reflected reflectometry signal received by the coupling unit has changed compared with a previous reflected reflectometry signal received by the coupling unit, with the change being one or more modulations caused by the modulation unit.

22. A network monitoring apparatus according to claim 20 or 21 , wherein the network monitoring apparatus has: a plurality of the coupling units, each coupling unit being associated with a respective first port included in a respective network channel of the network; and

a plurality of the modulation units, each modulation unit being associated with a respective second port included in a respective network channel of the network;

wherein the processing apparatus is configured to produce reflectometry data representative of reflected reflectometry signals received by the coupling units and to identify and/or map interconnections between the first ports and the second ports, based on an analysis of the reflectometry data.

23. A network monitoring apparatus according to any one of the previous claims, wherein the or each first port is located in a first patch panel of the network, with the or each second port located in a second patch panel of the network.

24. A network monitoring apparatus according to any one of the previous claims, wherein the or each coupling unit is configured to couple a reflectometry signal to a network channel such that the reflectometry signal propagates along the network channel between at least two twisted pairs in the network channel, and configured to receive a reflected reflectometry signal which has propagated along a network channel between at least two twisted pairs in the network channel.

25. A network monitoring apparatus according to any one of the previous claims, wherein the or each coupling unit is configured to couple a reflectometry signal to/receive a reflected reflectometry signal from a network channel by non- contact coupling with conductors of the network channel.

26. A network monitoring apparatus according to any one of the previous claims, wherein one or more modulation units are configured to modulate a signal propagating in a network channel by modulating an impedance of the network channel.

27. A network monitoring apparatus according to any one of the previous claims, wherein one or more modulation units are configured to modulate a signal propagating in a network channel based on a control signal.

28. A network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

29. A network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the network monitoring apparatus having:

a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to couple a ref!ectometry signal to the network channel that includes the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected reflectometry signal from the network channel;

a modulation unit associated with a second port included in a network channel of the network, wherein the modulation unit is configured to modulate a signal propagating in the network channel that includes the second port, and a processing apparatus configured to produce reflectometry data representative of a reflected reflectometry signal received by the coupling unit and to determine whether the first port is included in the same network channel as the second port of the network, based on an analysis of the reflectometry data that involves one or more modulations caused by the modulation unit.

30. A kit of parts for forming a network monitoring apparatus for determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the kit of parts having:

31. A kit of parts for forming a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the kit of parts having:

32. A kit of parts for forming a network monitoring apparatus for determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the kit of parts having:

a coupling unit associable with a first port included in a network channel of the network, wherein the coupling unit is configured to couple a reflectometry signal to the network channel that includes the first port and, if the reflectometry signal is reflected by any one or more discontinuities in the network channel that includes the first port, to receive the reflected reflectometry signal from the network channel; and

33. A method of determining whether one or more data signals are propagating within one or more twisted pairs of a network channel of a network, the method including: receiving a signal at a coupling unit associated with a first port included in a network channel of the network, wherein the coupling unit is configured to receive a signal which has propagated along a network channel between at least two twisted pairs in the network channel; and

34. A method of determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the method including:

35. A method of determining whether two ports are included in the same network channel of a network that includes a plurality of network channels, the method including:

36. A computer-readable medium having computer-executable instructions configured to cause a computer to control a network monitoring apparatus to perform a method according to any one of claims 33 to 35.

37. A network monitoring apparatus substantially as any one embodiment herein described with reference to and as shown in the accompanying drawings.

38. A method substantially as any one embodiment herein described with reference to and as shown in the accompanying drawings.