CN103843263B - The embedded optical time domain reflection test of optically amplified link - Google Patents
The embedded optical time domain reflection test of optically amplified link Download PDFInfo
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Abstract
Present invention provide for the optical fiber telecommunications system of optical communication network.The optic communication links that the present invention provides, utilizes the light data signal on different wave length wavelength division multiplexed channel between transmission fiber spans transmission node.The present invention discloses a kind of devices and methods therefor, this devices and methods therefor performs OTDR and LCV by using a light source on each node, to solve safety problem and to accelerate the integrity check to optical fiber link, the most again by high raman laser excitation light source applications to optical fiber link.Invention further discloses a kind of system the most only using a receptor.
Description
Cross-Reference to Related Applications
The application advocates filed in 12 days Augusts in 2011, Application Serial No. 61/523, the US provisional patent of 248
Right, this patent is included in the application by quoting.
Technical field
The present invention relates to the test of embedded optical time domain reflection and the link continuity check of light amplification optical fiber link.
Background technology
Before carrying out optical signal amplification, optical signal transmission on optical fiber transmission line can gradually weaken, typically in fiber-optic transfer
Need to carry out light amplification after transmitting 80 to 100km on line, first signal laser is converted into the signal of telecommunication and carries out signal of telecommunication amplification, afterwards
Reconvert heliogram, and continue on transmission line transmission.After introducing erbium-doped fiber amplifier, optical signal can transmit more
Far (2 to 3000km), and need not move through the conversion between the optical-electrical-optical that this is complicated, assembly is intensive and undesirable.
Image intensifer is since introducing, and its price is the most expensive, low-profile, and effective, therefore from 80 years
For being almost specifically designed to fibre-optic transmission system (FOTS) since mid-term.But, one that uses erbium-doped fiber amplifier to be amplified lacks
Point is, even best amplifier installation also can make by the noise of this device double.And use poor, typical amplification to fill
When putting, almost it is exaggerated four times by the noise (signal) of this amplifier.If made an uproar too much it is noted that amplifier has
Sound, then will limit optical signal maximum transmitted in glass delivery optical fiber after erbium-doped fiber amplifier amplifies away from
From.
Image intensifer had the biggest development in recent years, and it can be used for signal data rate 10Gb to 40Gb per second, even
It is that 100Gb is per second.The use of erbium-doped fiber amplifier is continuing, if but work under the speed of 100Gb per second, then each
Pulse is less, and energy is relatively low.Each pulse sent with specific speed has the energy of certain coupling/ratio.Compare
Speed is the pulse of 10Gb, and speed is that the pulse of 100Gb is little 10 times, therefore when signal transmits, puts into the energy of optical signal
Just lacked a lot.
Although using more clever scheme can obtain more light, but fundamental physics show, along with the increasing of pulse rate
Adding, luminous energy and photon numbers in optical signal always can be fewer and feweri.Owing to noise becomes a big chunk of signal, therefore may be used
Signal for data transmission also can become more weak, carries out test and become more to be stranded in these have the system of high signal rate
Difficult.It is therefore desirable to change amplifier occupation mode in telecommunication.
At the end of the nineties, a kind of by a large amount of laser inject Transmission Fibers improve the technology of amplification effect meet the tendency and
Raw.By using this technology rather than making signal along fiber-optic transfer power consumption, the excess energy in laser is through being situated between
It is converted into vibrational state during matter glass, thus allows to amplify all of optical wavelength.The laser of resonant excitation substantially maintains
The power of its pulse run into, and guarantee signal pulse not power consumption as similar non-excitation pulse.This just makes number
The number of it is believed that is transmitted farther in the case of not amplifying.This technology is by raman amplifier, and this amplifier passes through Raman effect
Realize producing light and the physical process of energy.The OTDR using Raman pump drapes over one's shoulders in the United States Patent (USP) of Patent No. 6,850,360
Dew, and be included in the application by quoting.
Use raman amplifier there is a problem that, this amplifier needs the most high-power laser, and this just means
This amplifier of use may be the most dangerous.Transmission line owner and operator do not like the high power that naked eyes cannot see and swash
, therefore, once there is adapter open circuit or damaged in light, the luminous energy that laser is sent just is easy to make people blind.Laser aid and
The safety criterion of equipment operation specifies in IEC60825 standard, and this standard has illustrated concrete operation measure and secure ID.
The Bureau of Standards of international telecommunication union telecommunication (ITU-T) has formulated the laser safety in standard G.664 communication system.According to standard
G.664, output should be able to be reduced to firm power by optical communication apparatus automatically, even automatically closes when laser occurs leakage
Close laser." automated power reduction " (APR) and " automated power closedown " (APSD) during G.664 this solution is referred to as solves
Certainly scheme.
It is necessary in an efficient way and uses minimum add-on assemble, adding transmission line monitoring function to optical amplifier
In system.Specifically, such as the decay along link, and link continuity check are monitored with optical time domain reflectometer (OTDR)
(LCV) it is used for determining and effectively closes bidirectional optical path between two nodes.
Summary of the invention
The system and method for the present invention meets above-mentioned needs, and with the most uncertain, succinct and highly effective
Mode implement solution with solve exist problem.Such as, wherein in an embodiment, only use single source real
Existing OTDR and LCV function, thus (a) prevents because the high luminous power in Raman amplifiction link causes optical fiber link to damage, and (b) is true
When protecting fault generation, in the eye-safe of the staff of optical fiber link work.Invention further discloses another kind of system and side
Method, including using single optical receiver, with uncertain on similar technology, succinct and effective manner, makes present demand obtain
To meet.
Optically amplified link monitoring system provides single source to generate optical signal, and carries out link seriality by optical signal
Inspection (LCV) test and optical time domain reflection (OTDR) are tested.Single source can be laser diode or Ramar laser.Amplify
After optical signal can with first direction through link, and for LCV test and OTDR test optical signal can with second direction (with
First direction is contrary) through link.Or, optical signal and the optical signal tested for LCV after amplification can be worn with first direction
Cross link, and the optical signal tested for OTDR can pass link with second direction (contrary with first direction).Test for LCV
With a normal base line power level, and the pulse on this baseline power level can be superimposed upon with the optical signal of OTDR test.Or
Person, the optical signal for LCV test and OTDR test with a zero base line power level, and can be superimposed upon this baseline power electricity
Pulse on Ping.
Fiber amplifier node can include the optical receiver of and the second optical connector optical coupling, this second optical connector with
Between two communication nodes, the first end of the second fiber segment (a total of a pair) connects, and this optical receiver is according to its program detection
OTDR and LCV signal.One with the first adapter and the light source of above-mentioned second adapter optical coupling, described adapter respectively with even
Being connected to the first end of the first fiber segment and the second fiber segment (a total of a pair) between communication node connect, this light source is used for generating
Detecting OTDR and the LCV signal between this node and another node, another node described is a pair optical fiber between communication node
Another node configured equally on section the second end, wherein, this light source above-mentioned first and second light simultaneously and between communication node
First end of fine section (a total of a pair) connects, thus generates optical signal to two adapters simultaneously.
Between monitoring two nodes of optical fiber link, the method for at least one pair of optical fiber includes: use the light source of first node to send out
Penetrate first node optical test pulse, two nodes in the first fiber segment at least one pair of optical fiber above-mentioned between two nodes
In first node launch to second node；Described first node detects described in described first fiber segment
The reflection of one optical tests pulse；Described second node detects described first in described first fiber segment received
Optical tests pulse；The light source using second node launches second node optical test pulse, a pair light between two nodes
In fibre, second node in two nodes in the second fiber segment is launched to first node；Described second node is examined
Survey the reflection of described second optical tests pulse in described second fiber segment；Described first node detects the institute received
State described second the optical tests pulse in the second fiber segment；Wherein, if exceeding presetting fixed system time parameter
T_PostponeTime in described first light whether received on described second node in described first fiber segment unconfirmed
Test pulse, then start line fault signal.
Between monitoring two nodes of optical fiber link, the another kind of method of at least one pair of optical fiber includes: use first node
Light source launches first node optical test pulse, between two nodes a pair optical fiber in the first fiber segment in two nodes
First node is launched to second node；Described first node starts detect described in described first fiber segment
The reflection of one node optical test pulse；Described in described first fiber segment that will detect on described first node first
The reflection of individual node optical test pulse contrasts with first reflection parameters specified；Wherein, if comparing result shows
The reflection of first node optical test pulse described in described first fiber segment detected on described first node meets institute
State appointment parameter, then continue this process；Wherein, if comparing result shows the institute detected on described first node
State the reflection of first node optical test pulse described in the first fiber segment and do not meet described appointment parameter, then start Article 1
Line fault signal；Wait T_ postponeTime, then start to detect described first fiber segment received on described second node
In described first node optical test pulse；Wherein, if it is confirmed that have been received by described first light on described second node
Described first node optical test pulse in fine section, then: use the light source of second node to launch second optical tests arteries and veins
Punching, between two nodes, a pair optical fiber, in the second fiber segment, second node in two nodes is sent out to first node
Penetrate；Described second node starts to detect the anti-of described second node optical test pulse in described second fiber segment
Penetrate；Described second node optical test pulse in described second fiber segment that will detect on described second node anti-
Second reflection parameters penetrated and specify contrasts；Wherein, detect on described second node if comparing result shows
To described second fiber segment in the reflection of described second node optical test pulse meet described appointment parameter, then continue
This process；Wherein, if comparing result shows the institute in described second fiber segment detected on described second node
The reflection stating second node optical test pulse does not meets described appointment parameter, then start the fault-signal of Article 2 circuit；
Wait T_ postponeTime, then start to detect described second in described second fiber segment received on described first node
Optical tests pulse；Wherein, if more than T_ postponeTime in unconfirmed on described second node, whether receive described
Described first node optical test pulse in one fiber segment, then start line fault signal.Wherein, above-mentioned fault is started
Signal can close closed system immediately.
Accompanying drawing explanation
To understand the concrete mode of features described above in more detail, and also can obtain more have by reference example with this
The description of body, some of them embodiment refers to accompanying drawing.However, it should be noted that accompanying drawing only illustrates typical embodiment, the most not
Should be regarded as limiting its scope, and also allow to quote other equally valid embodiments.
Fig. 1 is the schematic diagram of the optic communication links as example.
Fig. 2 is the optical time domain reflection test curve of pursuit illustrated example using Raman pump.
Fig. 3 be by the transmission of DFB light source measurement connect a pair fiber segment feature between two nodes connected mode and
Signal flow diagram.
Fig. 4 is to be measured by raman pump light source to transmit the system of a pair fiber segment feature connected between two nodes even
Connect mode and signal flow diagram.
Fig. 5 is to measure transmission by the optical receiver of single source and single monitoring and test pulse to connect between two nodes
The system connected mode of a pair fiber segment feature and signal flow diagram.
Fig. 6 is to show pulse timing and the vertical chronogram of startup on system interior joint A and B described in Fig. 5.
Fig. 7 is to show pulse timing and the flow chart of startup related description step on system interior joint A and B described in Fig. 5.
Detailed description of the invention
Those of ordinary skill in the art are well aware of the principle of OTDR, this principle lower described below.
Present application describes the application to OTDR and LCV test, install including system and start, the system during fault is examined
Disconnected, and field monitoring.
Fiber optic network is used for supporting voice communications versus data communications.In the fiber optic network using wavelength-division multiplex, use multi-wavelength
Light supports the multiple communication channels on simple optical fiber.
Raman amplification system needs a security system to guarantee that the two ends of link are all fully connected, and in Raman pump
Supply energy (or promoting energy) does not haves, before higher level, the situation that adapter is opened a way.Inspection both link ends is the completeest
The complete a kind of method connected is LCV (link continuity check).The function of LCV is to ensure that circuit is excellent and can grasp safely
Make.Present in Raman amplification system, risk is relevant to the overall height rated power (and energy) of Raman pump, once optical fiber (transmission
Line) somewhere still in activating Raman pump during open-circuit condition, just can cause the highest risk, be likely to result in operator's
Eye injury.Such as, the high-energy light escaped at fibre circuit open circuit may be irradiated to the eyes of operator, irradiation
Even if consequence will not make the blindness of operator, will also result in serious ocular injury.
For Raman amplification system, integrate OTDR (optical time domain reflectometer) function and test the collection total losses that optical fiber is possible
(uneven high signal attenuation region) is also advantageous, because they are often caused by dirty adapter, these dirts
Adapter easily burns and blackening because of higher raman pump power (energy), thus causes further signal attenuation.Tool
Saying, to carry out OTDR test to optical fiber link to front 20 to 50km before total power be extraordinary doing being started in Raman source body
Method.Although OTDR test result does not provide the information in terms of personal security, but they contribute positively to protection equipment.One dirty
Although dirty adapter does not results in the danger that light is escaped, but it is when being exposed under a luminous power the highest, it is also possible to
Burn and damaged, and make to be connected to this line failure burning adapter.So, OTDR analyzes and result contributes to
Protect transmission line and monitor the situation of transmission line, thus predict and arrange maintenance to shut down, in case the event of " in work " circuit occurs
Barrier and shutdown.
If display OTDR trace compares default circuit integrity or effectiveness specifies there is the biggest decay, then should
" substandard " result will start alarm, start line interruption and/or follow-up maintenance arrangement or maintenance immediately.
Fig. 1 shows the optic communication links 10 in Networks of Fiber Communications as example.Emitter 12 is by a series of light
Fine link transmits information to receptor 14.Each optical fiber link can include the fiber segment 16 of Transmission Fibers.Fiber segment 16 is permissible
It is about 200km, for long-distance network, or can be any other suitable length, the signal in Networks of Fiber Communications
Transmission.Link 10 can be a part for optical fiber ring network or any other suitable networks.
The communication link of Fig. 1 can be used for supporting WDM structure, it is provided that uses multiple communication channels of multi-wavelength light.Example
As, the link of Fig. 1 can support to have the system of 40 channels, and each channel uses different optical carrier wavelength.Light is believed
Road can be modulated by the transmission speed of e.g., from about 10Gbps (OC-192).The optical carrier wavelength used can be on 1527 to 1605nm
Under.These system features being merely exemplary.If needed, it is possible to provide little channel (such as a channel), or can carry
For more channel (such as hundreds of channel), signal can be carried on multiple wavelength (as used optical code division multiple access (CDMA) knot
Structure), signal can be by more slowly or faster data rate modulation (such as the speed of OC-48 about 2.5Gbps or OC-768 about 40Gbps
Speed), and different optical carrier wavelength (if scope is the wavelength of 1240 to 1670nm) can be supported.
Image intensifer 18 can be used for amplifying the optical signal on link 10.Image intensifer 18 can include power amplifier, light
Line amplifier and light preamplifier.Image intensifer 18 can be the fiber amplifier containing rare earth, such as erbium-doped fiber amplifier,
Or comprise discrete Raman pump coil amplifier, comprise and be passed to excited Raman effect for optical pumping transmission fiber spans 16
Produce the pumped amplifier of the gain of light, semiconductor optical amplifier or any other suitable image intensifer.
Raman pump module 20 can be used for providing raman pump light for fiber segment 16.Raman pump light is imitated by excited Raman
Raman gain should be formed in fiber segment 16.Each Raman pump module can pass through laser diode, optical fiber laser or its
He provides Single wavelength or the pump light of multi-wavelength at suitable pump light source.Although the device of Fig. 1 relates to fiber segment 16 and Raman pump
The reverse enhancing of Pu light, but if it is desired, fiber segment 16 also can strengthen with raman pump light jointly.
Computer equipment 22 can be used for realizing NMS.Computer equipment 22 can be placed in network node and/or
On network management facility.As shown in dotted line 24, NMS can be by suitable communication path and image intensifer 18, transmitting
Device 12, receptor 14, Raman pump module 20 and other optical network units carry out communication.Communication path can based on any properly
Light path or circuit.Such as, communication path (as represented by dotted line 24) can include service or telemeter channel path, wired or wireless
Communication path, and may relate to the communication road formed by the normal data of relatively small modulation depth on slowly modulation link 10
Footpath.Communication path (being represented by dotted line 24) can be additionally used in the Direct Communication between Raman pump module 20 and image intensifer 18.
Link 10 may also include optical network unit module, such as interpolation/removing module, photoswitch, dispersion compensation module, moves
State filtering module or any other suitable optical network unit.
Fig. 2 shows that the Raman pump of the use Raman pump module as example carries out the tracking of optical time domain reflection test
Curve 82, it is obtained by control unit and the supervising device of computer equipment 22.In the figure 2 example, reflection signal power
(i.e. the reflection pump power of Raman pump module 20 Raman pump) is noted as time function.If it is desired, in Fig. 2 in x-axis
Time scale can based on feature known to fiber segment 16 (as group speed) be converted into range scale.Y-axis (power) quilt in Fig. 2
It is labeled as logarithm (dB) scale.
Aircraft pursuit course 82 shows the multiple features in the fiber segment 16 of example.For example, it may be determined that seam, crack, cut
Mouth and the position of adapter.If the control unit of computer system 22 detects that fault is (such as crack or the company that should not disconnect
Connect device), then this control unit can generate alarm, and the power that can reduce Raman pump (is such as reduced to zero or other are to eyes
The level of safety).If there is no any otch, then also can measure the total length of fiber segment 16.
Follow the tracks of data and can be additionally used in the optical fiber identified in fiber segment 16.Different types of optical fiber can be used for fiber segment 16 not
Same part.Such as, fiber segment 16 may comprise standard single-mode fiber (SMF), dispersion compensating fiber (DCF) or other kinds of light
Fine.Different types of optical fiber has different unit length losses and effective core area (A.sub.EFF).If aircraft pursuit course
82 are noted as logarithmic scale as shown in Figure 2, then aircraft pursuit course 82 the slope of given area and the numerical value of A.sub.EFF in
Negative correlation.In this example of Fig. 2, as shown in slope characteristics, the optical fiber of SMF and DCF both types is used for fiber segment 16
Different piece.The information that in fiber segment 16, fiber type is relevant is available for control unit and the NMS of computer equipment 22
System is for determining that Raman pump module 20 and the suitable pump power of image intensifer 18 and other are arranged.
If it is desired, Raman pump module 20 can use monitoring and supervising device to measure different Ramans in fiber segment 16
The signal power of pumping level, so that control unit can collect the letter of the switch Raman gain produced by Raman pump module 20
Breath.These turn off gain measurement results can be combined with the optical measurements carried out in each pumping wave strong point, thus further
The feature of difference fiber segment 16.
Image intensifer is used for amplifying optical signal in fiber optic network.Such as, image intensifer can be used for being amplified in optical line
The light data signal decayed on footpath.One typical amplifier can include by the Er-doped fiber line of diode laser pumped
Circle.Image intensifer also can comprise Raman pump laser, to be made the transmission being connected with erbium-based amplifier by Raman effect
Optical fiber obtains the more gain of light.The transmission direction of Raman pump signal is generally set to and data signal transmission direction phase
Instead.
System is installed and the purpose of startup is: determines the fibre circuit loss situation of transmission link, thus optimizes Raman
Pump power, and before starting Raman pump, identify the adapter/seam of loose contact.Continuous system diagnosis accident analysis solves
Function includes: location fibercuts, field monitoring and each point positioning and slowly degenerating on monitoring transmission line, thus
Promote to arrange preventative maintenance before degeneration develops into beyond thought optical fiber link fault.
In one embodiment, single light source at each node generates test signal, this signal with institute on optical fiber link
Carry the contrary direction of data signal to transmit.Two kinds of variants are illustrated with the configuration of display in Fig. 3 and 4.A kind of wherein
In variant, DFB (distributed feed-back) emitter includes a laser diode, and this diode can generate test signal, is used for carrying out
OTDR and LCV tests.In another kind of variant, with (controlled energy) Ramar laser as generating OTDR and LCV test
Light source with test signal.
In Fig. 3 and Fig. 5 is to 7, it is marked as the single light source of " DFB TX " for generating the light letter of LCV and OTDR test
Number.
According to Fig. 3, at node B, as DFB TX 100 (DFB emitter 100) Distributed Feedback Laser (emitter) to
Top optical fiber 70 provides a pulse (such as 37) and DC level (such as 35) (high level basis signal non-dc electricity
Flat, but the fiber-optic signal of similar baseline signal level is arranged, background signal (about 1mW) represents unglazed).During typically for light
For domain reflectometer (OTDR), test pulse shows as light unglazed, full and unglazed.DFB TX at Fig. 3 interior joint A and B
The 100,200 test signals launched are assessed for OTDR and LCV.(emitter) sends light pulse, and this pulse is used for assessment
OTDR, and it is added to the top of light DC level, dotted line 80 expression returns to OTDR signal receiver RX OTDR 102
The path of the reflected impulse of (OTDR signal receiver 102).Transmission DFB TX (100,200) sends pulse, by dotted line 76 and arteries and veins
Punching 37 represents, and part light pulse is reflected back toward receptor RX OTDR 102 along top optical fiber 70.Dotted line 74 represents that baseline is believed
The path (through the pip of OTDR) of numbers 35, therefore, if optical fiber stands intact, then the test signal of remainder is (extremely
It is baseline test signal level less) will be through whole fiber segment, and at node A, RX (LCV) 204 will receive this signal.If
Node A receives the test signal that node B sends along top optical fiber 70, then DFB TX 200 will be promoted along bottom optical fiber 72
It is transmitted back to a pulse to node B, and is received to complete circulation by receptor RX (LCV) 104, use notice node B and have been received by
Test pulse.Owing to pulse (being represented by dotted line 73) sends (bottom optical fiber along bottom optical fiber 72 to node B from node A
The back reflection pattern of 72 is not shown in the diagram), therefore receptor RX OTDR 202 can while listening for and carry out bottom optical fiber 72
OTDR assessment.
Node B, after the signal receiving node A, just has confirmed that the bottom optical fiber 72 towards node B is also safe (this
Process illustrates in timeline and the flow process of Fig. 6 and 7, and discussed further below).Therefore, at node A and node
Between B, system validation optical fiber or two optical fiber (section) (also known as " a pair optical fiber ") stand intact.Once optical fiber channel syndrome is the most intact
Lossless (or light sealing), higher power Raman pump can open (or rising to high-energy from low-yield).
In the past, OTDR test completed by Raman pump, as the U.S. is special in the case of not carrying out link continuity check
Profit US 6,850,360 B1.One shortcoming of Raman pump is that the optical wavelength of use such as glass power can be decayed rapidly.Light
The Glass Design used in fibre is to work under the wavelength of 1550nm, and when Raman pump carries out pump under the wavelength of about 1450nm
During Pu, energy will be decayed rapidly, thus without transmitting the most remote.Between node, fiber segment Part I is drawn by low-yield
The OTDR that graceful light source is carried out analyzes the situation only demonstrating this Part I.Use low-yield Raman light source cannot complete whole section of light
Fine checking, therefore uses a kind of miniature laser DFB being dirt cheap instead.
Signal processing described herein and sequence provide the signal of auto-sequencing, between node A and B launch and
Receive, be used for assessing OTDR and LCV.An operator or technician can be sent in the past to node B, and sent another operator
Or technician is to node A, then they discuss OTDR and link testing procedure by phone.
Operation described herein is provided convenience effective optical fiber integrity check, and operator or technician without
Leave control room.High power Raman light source can be controlled at node A and B, the most persistently guarantees the peace of personnel in this region
Entirely, and by the control element of each node make decision.Between node B and node A, and it is used for examining between node A and node B
The decision making process and the communication automatization that test a pair fiber segment between node are the most disclosed.
Only using Ramar laser (generating laser by Raman pump) is also can as the light source of OTDR and LCV test
Row, as shown in Figure 4.But, this needs Raman pump laser design of drive circuit becoming to be able to ensure that, LCV test is used up
Power level is maintained at the low level of a safety, even if when drive circuit breaks down.Due in optical fiber OTDR pulse and
The existence of reflection, therefore also can result in data signal and occurs a certain degree of deterioration in transmitting procedure.
Fig. 4 only uses Raman pump signal carry out OTDR and LCV test, there is not DFB TX.RX OTDR 250,260
It is the receptor of OTDR signal, and RX LCV 252,262 are used for receiving link inspection signal.Solid line and dotted line 70 ', 72 ',
73 ', 74 ', 76 ' is corresponding with the function of the solid line shown in Fig. 3 and dotted line 70,72,73,74,76 and 80 with 80 '.
In one embodiment, carry out LCV test with baseline DC optical power level, and be superimposed with OTDR pulse (as
Under 1kHz, there is the dutycycle of 0.1%).But, identical light pulse is used for OTDR test and LCV signal is also feasible,
Therefore, LCV function need not single DC optical power level.This perhaps can produce more preferable OTDR sensitivity.But by
Must be sufficient to ensure that the correct operation of LCV in pulse parameter, this can cause losing spirit in the ability arranging OTDR pulse parameter
Activity.
In another embodiment, single light source at a node generates OTDR and tests signal, this test signal with
The direction that data signal on optical fiber link is contrary is transmitted, and LCV test signal is then with identical with data signal on optical fiber link
Direction transmit.Accompanying drawing 5 illustrates this embodiment, and wherein DFB TX 300,400 emitter at each node includes
One laser diode, this laser diode generates with data signal rightabout (by optical fiber 310, the big solid line on 320 and void
Thread triangle shape representation) OTDR that transmits tests signal, and the LCV transmitted with data signal equidirectional tests signal.Fig. 5
In DFB signal transmit in the opposite direction with data signal.On top optical fiber 310, data signal is sent to node from node A
B.Data signal on the optical fiber 320 of bottom transmits from right to left.Owing to using single light source and single receptor to carry out OTDR survey
Examination and LCV test, and therefore the use between both test patterns of these equipment uses time-division multiplex technology.
Fig. 6 and 7 illustrates the agreement that structure shown in Fig. 5 switches between OTDR test pattern and LCV test pattern.
The protocol define " waiting at random " and " delay ", to prevent adjacent node from starting transmitting pulse and during operating continuously simultaneously
Time delay, by the anticipated time receiving OTDR pulse with estimate to receive link check pulse time spaced apart.
Transmission Fibers shown in Fig. 5 only includes a DFB TX (emitter) 300,400 and one at individual node
RX OTDR (receptor) 302,402.
RX OTDR 302 at node B is reflected signal and the receptor of link inspection DFB signal.DFB at node B
TX 300 launches pulse to the left along top optical fiber 310 and bottom optical fiber 320.Reflected impulse on top optical fiber 310 is anticipated will
Receiving at node B, this reflected impulse will be received by RX OTDR 302.(at node B, it is not detected by the reflection on the optical fiber of bottom
Pulse).
DFB TX 400 at node A also launches laser along top optical fiber 310 and bottom optical fiber 320 to node B simultaneously, with
Check the link seriality of top optical fiber 310 and provide an OTDR pulse signal to bottom optical fiber 320.If node B (is receiving
At device RX OTDR 302) have received and at node A, launch the laser of coming, then show that top optical fiber 310 does not has fault.
How differentiating the signal sent to is a potential problem.There may be two groups of DFB laser signals to send at node B
RX OTDR 302 (reflected signal that node B launches and the primary signal that node A launches), it is necessary to tell the two signal.
Such as adding a pulse code at node A in the transmitting signal of DFB TX 400, such receptor just can lock and send back
The signal form (thus coming with other signal distinguishing) of RX OTDR 302 at node B.If receive is signal code, connect
Receive device and then can learn this code, because receptor this particular code to be received such as.If being properly received, then inform system
Optical fiber stands intact.Compared with other structures, in this structure, at each node, only use a receptor, such as 302,402
Deng, and without another receptor of reprogram, and by its access system, thus reduce complexity and saving expense.
Vertical chronogram shown in Fig. 6 illustrates between adjacent node that normal (do not have out of order optical fiber to) signal passes
Defeated, including OTDR reflection and link testing sequence, it is shown that two cyclic processes.In the case of running well, this process
Once, will be sustained.Fig. 7 show the process steps occurred at a node, the ginseng of these process steps
Examine numbering launch at node A shown in Fig. 6 and node B for following the trail of and receive signal, i.e. between node A and node B
OTDR and LCV.
As it is shown in fig. 7, this process starts to be sustained from startup.Once " startup " (120), by Node Timer
" T " resets zero, (122) step that i.e. " resets time T=0 ", then " monitored link check pulse " (123), later evaluation " whether
Link check pulse is received from other nodes " (124).If not from other reception at Node to pulse (124), then assessment " is
No T > T_ is random " (130) (in this embodiment, what T_ was random arranges the value about 0.1-1.0 second)." if whether T > T_ is random "
(130) answer is "No", then this process returns to " monitored link check pulse " (123) step." if whether T > T_ is random "
(130) answer is "Yes", then enter " transmitting pulse " (132) step.If it addition, " whether from other reception at Node to chain
Road check pulse " answer of (124) is "Yes", then carry out " resetting time T=0 " (126) step, subsequently enter and " wait until T
>T_ postpone" (128) step, start " transmitting pulse " (132) step afterwards.
Relatedness between chronogram shown in process steps shown in Fig. 7 and Fig. 6 will be explained.First, it is assumed that with joint
The transmission of optical signal between some A and node B, process is just being carried out along set process steps " normally ", and fault-free or assessment walk
Suddenly can cause this process deviation set procedures or rest in branching process.(opened by activating when node as shown in Figure 6
Dynamic) time, node A, B simultaneously enter the process of " waiting at random "." waiting at random " process shown in Fig. 6 includes " waiting at random " literary composition
The process steps (see and number identical process steps in Fig. 7) of explanation in the other rectangle frame of word, i.e. step 120,122,123,124
With 130." wait " that process one terminates at random, then enter " transmitting pulse " process, i.e. step 132, to send out to node B from node A
Penetrate light pulse.As it is shown in figure 5, in this embodiment, pulse is launched along top optical fiber 310 and bottom optical fiber 320 simultaneously.
Return to Fig. 7, it is known that after " transmitting pulse " (132) step completes, then sequentially enter " resetting time T=0 " step
Suddenly (134), " capture OTDR return signal " (136) step, " whether T > T_ postpone" (138) assessment and " monitored link check pulse "
(142) step.
As shown in Figure 6, the dotted line that the OTDR RX process at node A points to lower-left with the arrow sent from solid line represents,
Represent that optical signal is just launched to node B from node A.Ref. No. (i.e. step 134,136,138,140 and 142) in rectangle frame
Formed corresponding with the process steps in Fig. 7.
In Figure 5, return dotted line 350 expression is the light that in the optical fiber 320 of bottom, OTDR is reflected back node A.
At the node B shown in Fig. 6, " waiting at random " and " delay " process are carried out with reference to the process steps order in Fig. 7,
Step Ref. No. is positioned at the rectangle frame of process title side, i.e. 120,122,123,124,126 and 128.With node B it is
Example, after receiving pulse at node A, node B resets its timer to dead-center position, through T_ postponeThe wait of time, starts
" transmitting pulse " process of entrance, as it is shown in fig. 7, the representative numbering of this process and coherent reference numbered 132." sending out at node B
Penetrate pulse " (132) one emitted, the dotted line that OTDR RX process at node B points to bottom right with the arrow sent from solid line carrys out table
Show, represent that optical signal is just launched to node B from node A.Ref. No. (i.e. 134,136,138,140 and 142) in rectangle frame
Formed corresponding with the process steps in Fig. 7.
In Figure 5, return dotted line 330 expression is the light that in top optical fiber 310, OTDR is reflected back node B.
Return to Fig. 7, it is known that after " monitored link check pulse " (142) step completes, then begin the evaluation at " whether from it
His node receives link check pulse " (144).(144) are assessed " whether to receive link check pulse from other nodes "
If result "Yes", then this process will proceed to the assessment of " OTDR curve of pursuit is the most normal " (152), if the result of this assessment
For "Yes", then enter " unlatching Raman pump " (154) step and " closedown alarm " (156) step.
Shown in Fig. 6 to " link inspection " above-mentioned steps that activity/process is relevant at node A, with its side rectangle frame
In Fig. 7 in step Ref. No. form correspondence, i.e. 144,152,154 and 156.
It addition, as it is shown in fig. 7, the knot of " if whether receiving link check pulse from other nodes " (144) assessment feedback
Fruit is "No", then subsequently enter " whether T > T_ postpone" (146) assessment.If " whether T > T_ postpone" (146) result of assessing is "No",
Then repeat " monitored link check pulse " (142) step.If " whether T > T_ postpone" (146) result of assessing is "Yes", then enter
" closedown Raman pump " (148) step and " unlatching alarm " step.Once " unlatching alarm " step, then process may stop
Or return to " reset timer T=0 " (122) step and restart assessment.
As it is shown in fig. 7, another optional process path is: if the feedback that " OTDR curve of pursuit is the most normal " (152) are assessed
Result is "No", then this process proceeds to " closedown Raman pump " (148) step and subsequent step thereof.
As it is shown in fig. 7, elapse forward process steps from " closedown alarm " (156) step, through " resetting timer T=0 "
(158) step and " waiting until T > T_ postpone" after (160) step, time delay is equivalent to " T_ postpone", subsequently enter " transmitting pulse "
(132) step.
As shown in Figure 6, next process at node A is " delay " process, operation corresponding diagram 7 respective rectangular of this process
Frame indicates the process steps of Ref. No. 158 and 160, subsequently enters " sending out at next movable (process steps), i.e. node A
Penetrate pulse " process, corresponding diagram 7 respective rectangular frame indicates the process steps of Ref. No. 132, proceeds to reference at node A afterwards
" OTDR RX " process/activity of numbered 134,136,130,140 and 142 and Ref. No. are 144,152,154 and 156
" link inspection " movable.
The process steps now the most completely described by Fig. 7 is used as the reference that Fig. 6 illustrates the remaining timing of bursting activity.Node A
After " transmitting pulse " process at place completes, proceed to " OTDR RX " at node A movable, i.e. step 134,136,138,140 and
142." delay " process (i.e. step 158 and 160) and " transmitting pulse " process (i.e. step 132) is entered with from node B at node B
Launch pulse to node A, at node B, start " OTDR RX " activity/process (i.e. step 134,136,138,140 and simultaneously successively
142), " link inspection " is movable (i.e. step 144,152,154 and 156).Last activity at node A shown in Fig. 6 is " delay "
Activity/process (i.e. step 158 and 160).
The signal received is estimated by described process steps, if assessment result display signal is down to a certain threshold values or mark
Below standard, then malfunction occurs, causes alarm to be sounded, and Raman light source is closed.
Shown in Fig. 7, flow chart is only applicable to embodiment illustrated in fig. 5.Fig. 5 is shown that a receptor and is used simultaneously as link
Inspection and OTDR function.In this structure, receptor have to know when should be at OTDR pattern, and when should be at link inspection
Test pattern.Fig. 3 and embodiment illustrated in fig. 4 structure have the independent receiver being respectively dedicated LCV and OTDR function, therefore without examining
Consider the probability of blurring.
Typically, under normal circumstances, node A launches pulse to process, and once Node-B receiver is to after this pulse, then prolongs
After the slow a certain set time, i.e. send back a pulse to node A.This pulse the most just comes between node A and node B
Passback is sent.As to how the startup between management node A and node B (sets up system, so that only having an arteries and veins between two nodes
Bring passback to send), this problem must be solved.It is a risk that when the two node is initially opened, if two joints
Point launches pulse simultaneously, then two nodes will be unable to determine that the pulse received is in response to pulse or OTDR pulse, then
System may be thrown into confusion.Chaotic in order to avoid this type of, normally used mode be start after random when waiting one section
Between.If receiving pulse at waiting time, then illustrate that this pulse is apparently not from this node, and the most another from optical fiber
That node of one end, that node has been started up, and launches pulse to this node.In this case, from reception
Rising during to external pulse, present node i.e. enters normal processes.Here it is " waiting at random " effect that state procedure is to be reached.
If after receiving an external pulse, stop random waiting process, then enter normal impulse ejection process.
Once being built in the optical fiber structure of normal operation by OTDR, system control device can enable Systems Operator remote
Journey access network, Telnet is in the equipment of any position in networking, in order to observe OTDR and LCV described herein real-time
Situation about reporting.
As herein described, use minimum hardware to realize the link seriality of OTDR and LCV.Such as in this case,
Single light source is used to perform the function of OTDR and LCV at each node.Use single light source, then without using energy to go to drive
Dynamic other light sources, therefore can reduce energy expenditure.The reduction of power consumption requirements also improves the feature of environmental protection of system simultaneously.Use
Single light source, it is possible to decrease system and the complexity of control element, improves system reliability simultaneously, and herein described use is single
The structure that optical receiver is assessed in OTDR and LCV also has similar effects.
Although preceding description is directed to the embodiment with the present invention as foundation, but can be without departing from elemental range of the present invention
On the premise of other and subsequent embodiment are modified, the elemental range of the present invention is bound by claim.
Claims (11)
1. for a monitoring system for optically amplified link, including:
The single light source for generating optical signal being located on the fiber amplifier node of described optically amplified link, the optical signal of generation
Test for implementing link continuity check (LCV) test and optical time domain reflection (OTDR)；Described fiber amplifier node is referred to as
First fiber amplifier node, is referred to as the second fiber amplifier node, described second fiber amplifier by its next fiber amplifier node
Node and the first fiber amplifier node have identical configuration；By at least one pair of optical fiber pair between two fiber amplifier nodes:
First fiber segment and the second fiber segment connect；Described single light source and the coupling of the first fiber segment, send out to the second fiber amplifier node
Send test optical signal；
It is located at the optical receiver on the first fiber amplifier node, for receiving LCV test and the test optical signal of OTDR test；
It is located at the Ramar laser on the first fiber amplifier node, for generating Raman gain signal to amplify the communication in link
Optical signal；
One controller, the test optical signal situation received based on described optical receiver, control single light source and generate LCV test
The test optical signal tested with OTDR, and regulate the power level of described Ramar laser；
Single light source on first fiber amplifier node sends test optical signal, or the second optical fiber to the second fiber amplifier node
The single light source amplified on node sends test optical signal to the first fiber amplifier node, between test two Fiber Nodes extremely
The seriality of few a pair optical fiber pair and optical time domain reflection；
The LCV that optical receiver on second fiber amplifier node receives from the first fiber amplifier node tests signal, and comes
Optical time domain reflection signal from the test optical signal of the second fiber amplifier node；
Optical receiver on first fiber amplifier node receives the optical time domain of the test optical signal from the first fiber amplifier node
Reflected signal, and the LCV test signal from the second fiber amplifier node；
Described controller monitors whether the optical receiver on two adjacent fiber amplifier nodes receives intended test light letter simultaneously
Number, and according to optical receiver receive test optical signal situation judge at least one pair of optical fiber pair between two fiber amplifier nodes
Seriality and optical time domain reflection situation, thus control single light source continuation transmission test optical signal and carry out next round monitoring and regulate
The power level of Ramar laser, or carry out fault alarm.
2. system as claimed in claim 1, wherein, single light source is laser diode.
3. system as claimed in claim 1, wherein, single light source is Ramar laser.
4. system as claimed in claim 1, wherein, the optical signal of amplification orients transmission in the first direction through link, and is used for
The optical signal of LCV test and OTDR test then orients transmission in a second direction through link, and second direction is contrary with first direction.
5. as claimed in claim 1 system, wherein, the optical signal of amplification and for the optical signal of LCV test through chain curb the
One direction orientation transmits, and the optical signal for OTDR test then orients transmission in a second direction through link, second direction with
First direction is contrary.
6. system as claimed in claim 1, wherein, the optical signal for LCV test and OTDR test includes normal base line power electricity
Flat, and the pulse of superposition on the basis of baseline power level.
7. system as claimed in claim 1, wherein, the optical signal for LCV test and OTDR test includes zero base line power electricity
Flat, and the pulse of superposition on the basis of baseline power level.
8. as claimed in claim 1 system, wherein, described light source is simultaneously and between communication node described the first of a pair fiber segment
First end of optical fiber and the second optical fiber connects, thus launches optical signal to two adapters simultaneously.
9. between monitoring two nodes of optical fiber link, the method for at least one pair of optical fiber includes:
The light source using first node launches first node optical test pulse, between two nodes a pair optical fiber first
In fiber segment, first node in two nodes is launched to second node；
Described first node detects the reflection of described first optical tests pulse in described first fiber segment；
Described second node detects described first the optical tests pulse in described first fiber segment received；
The light source using second node launches second optical tests pulse, the second optical fiber a pair optical fiber between two nodes
Second node in upper two nodes of section is launched to first node；
Described second node detects the reflection of described second optical tests pulse in described second fiber segment；
Described first node detects described second the optical tests pulse in described second fiber segment received；
Wherein, if exceeding presetting fixed system time parameter T_PostponeTime in unconfirmed at described second node
On whether receive described first the optical tests pulse in described first fiber segment, then start line fault signal.
10. between monitoring two nodes of optical fiber link, the method for at least one pair of optical fiber includes:
The light source using first node launches first node optical test pulse, between two nodes a pair optical fiber first
In fiber segment, first node in two nodes is launched to second node；
Described first node starts to detect the anti-of described first node optical test pulse in described first fiber segment
Penetrate；
Described in described first fiber segment that will detect on described first node, first node optical test pulse is anti-
First reflection parameters penetrated and specify contrasts；
Wherein, if comparing result shows described in described first fiber segment detected on described first node first
The reflection of node optical test pulse meets described appointment parameter, then continue this process；
Wherein, if comparing result shows described in described first fiber segment detected on described first node first
The reflection of node optical test pulse does not meets described appointment parameter, then start first line fault signal；
Wait T_PostponeTime, then start to detect described in described first fiber segment received on described second node
One node optical test pulse；
Wherein, if it is confirmed that described first the node flash ranging having been received by described second node in described first fiber segment
Examination pulse, then:
The light source using second node launches second optical tests pulse, the second optical fiber a pair optical fiber between two nodes
Second node in upper two nodes of section is launched to first node；
Described second node starts to detect the anti-of described second node optical test pulse in described second fiber segment
Penetrate；
Described second node optical test pulse in described second fiber segment that will detect on described second node
Reflection contrasts with second reflection parameters specified；
Wherein, if comparing result shows described second in described second fiber segment detected on described second node
The reflection of individual node optical test pulse meets described appointment parameter, then continue this process；
Wherein, if comparing result shows described second in described second fiber segment detected on described second node
The reflection of individual node optical test pulse does not meets described appointment parameter, then start the fault-signal of Article 2 circuit；
Wait T_PostponeTime, then start to detect described in described second fiber segment received on described first node
Two optical tests pulses；Wherein, if more than T_PostponeTime in unconfirmed on described second node, whether receive institute
State described first the node optical test pulse in first fiber segment, then start line fault signal.
11. methods as claimed in claim 10, wherein, start described fault-signal and can close closed system immediately.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201161523248P | 2011-08-12 | 2011-08-12 | |
| US61/523,248 | 2011-08-12 | ||
| PCT/US2012/050625 WO2013025630A1 (en) | 2011-08-12 | 2012-08-13 | Embedded optical time domain reflectometer for optically amplified links |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103843263A CN103843263A (en) | 2014-06-04 |
| CN103843263B true CN103843263B (en) | 2016-11-30 |
Family
ID=
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| US5077729A (en) * | 1989-03-28 | 1991-12-31 | Gec-Plessey Telecommunications Limited | Testing optical fiber links |
| US6028684A (en) * | 1996-10-23 | 2000-02-22 | Tyco Submarine Systems Ltd | Path to provide OTDR measurements of an optical transmission system that includes optical isolators |
| US6178025B1 (en) * | 1997-12-03 | 2001-01-23 | Nortel Networks Limited | Optical network loss-of-signal detection |
| US6850360B1 (en) * | 2001-04-16 | 2005-02-01 | Bookham, Inc. | Raman amplifier systems with diagnostic capabilities |
| US7561798B2 (en) * | 2003-03-07 | 2009-07-14 | Verizon Services Corp. | Testing a fiber link in a communication system without interrupting service |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5077729A (en) * | 1989-03-28 | 1991-12-31 | Gec-Plessey Telecommunications Limited | Testing optical fiber links |
| US6028684A (en) * | 1996-10-23 | 2000-02-22 | Tyco Submarine Systems Ltd | Path to provide OTDR measurements of an optical transmission system that includes optical isolators |
| US6178025B1 (en) * | 1997-12-03 | 2001-01-23 | Nortel Networks Limited | Optical network loss-of-signal detection |
| US6850360B1 (en) * | 2001-04-16 | 2005-02-01 | Bookham, Inc. | Raman amplifier systems with diagnostic capabilities |
| US7561798B2 (en) * | 2003-03-07 | 2009-07-14 | Verizon Services Corp. | Testing a fiber link in a communication system without interrupting service |
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