CA1203576A - Military radar - or radio communications transmission system - Google Patents
Military radar - or radio communications transmission systemInfo
- Publication number
- CA1203576A CA1203576A CA000307208A CA307208A CA1203576A CA 1203576 A CA1203576 A CA 1203576A CA 000307208 A CA000307208 A CA 000307208A CA 307208 A CA307208 A CA 307208A CA 1203576 A CA1203576 A CA 1203576A
- Authority
- CA
- Canada
- Prior art keywords
- sub
- frequency
- bands
- programme
- jamming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/20—Countermeasures against jamming
- H04K3/28—Countermeasures against jamming with jamming and anti-jamming mechanisms both included in a same device or system, e.g. wherein anti-jamming includes prevention of undesired self-jamming resulting from jamming
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/38—Jamming means, e.g. producing false echoes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/40—Jamming having variable characteristics
- H04K3/41—Jamming having variable characteristics characterized by the control of the jamming activation or deactivation time
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/40—Jamming having variable characteristics
- H04K3/42—Jamming having variable characteristics characterized by the control of the jamming frequency or wavelength
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K2203/00—Jamming of communication; Countermeasures
- H04K2203/30—Jamming or countermeasure characterized by the infrastructure components
- H04K2203/34—Jamming or countermeasure characterized by the infrastructure components involving multiple cooperating jammers
Abstract
ABSTRACT
This invention relates to a military radar- or radio communications system, in particular with mobile transmitting and receiving equipment, permitting a continuous change of a plurality of operating frequencies in accordance with a method of sudden frequency changes. In the periods when the transmitter is not required for the transmission of inform-ation signals, such as intervals in communication, the trans-mitter is used for jamming on those frequencies or frequency sub-bands which are not required for the transmission of information signals at that time.
This invention relates to a military radar- or radio communications system, in particular with mobile transmitting and receiving equipment, permitting a continuous change of a plurality of operating frequencies in accordance with a method of sudden frequency changes. In the periods when the transmitter is not required for the transmission of inform-ation signals, such as intervals in communication, the trans-mitter is used for jamming on those frequencies or frequency sub-bands which are not required for the transmission of information signals at that time.
Description
l'his invention relates to a military radar- or radio communications transmission system, in particular with mobile transmitting and receiving equipment, permitting a continuous change of a plurality of operating frequencies according to a method of sudden frequency changes.
Systems operating with methods of sudden frequency changes have become known from United States Patent 3,426,279, for example. In these systems a leaping change in operating frequencies is carried out in accordance with a predetermined pattern, of which all stations participating in the communic-ations activity are aware. This pattern may he stored, for example, for a period of time, such as a day, in an on board computer. On board computer systems of this kind generally form part of the cryptological equipment and do not require any substantial additional resources for solving any further tasks. In principle, these aspects likewise apply to position-fixing.
It is the object of the present invention, to carry out in a frequency-changing system of the aforestated kind effective jamming of an enemy's transmission oE intelligence, without interfering with one's own transmission.
According to the present invention, there is provided a method of operating a military radar or radio communications system having a plurality of stations each having a transmitter and receiver, said method comprising using rapidly changed frequencies within a sub-band of a plurality of sub-bands oE
available frequencies for transmitting and receiving information signals and using any of the transmitters which are not engaged in transmitting information signals to transmit jamming signals on the sub-bands not then being used to transmit information . . ~ 1 -~;Z V3~6 signals, and changing at controlled time intervals the sub-band in which information signals are transmitted and received and the remaining sub-bands on which jamming signals are trans-mitted.
This offers a highly effective opportunity to use ECM (Electronic Counter Measures), especially in the area of operation, where a great effect can be achieved without great transmitter power. This applies in particular to those systems operating with a central and thus remote jamming station - la -~2~1~3~
which cannot be operated in the intermediate vicinity of the area of operation and which would be much easier to detect by the enemy's defence. In mobile stations, which are expected to operate in the front area, such as tanks or missiles, the locating of the enemy is of secondary importance, because the vehicles or missiles have to expose themselves by nature.
It is possible with the aid of relatively low transmitt0r power to effectively interfere with an enemy's intelligence or position-finding system, without principally shortchanging one's own transmission of intelli-gence or radio determination.
The present invention will be further discussed below with the aid of three Figures as follows:
Figure 1 is a schematic diagram of a system according to the invention.
Figure 2 is a block diagram of a transmitter.
Figure 3 is a detailed block diagram of a transmitting and receiv-ing station.
Figure 1 defines an area by means of a rectangle, where a plural-ity of vehicle stations T of one's own and G of the enemy's radio stations are located. These radio stations are generally mobile, for example tank units.
As stated above, these stations operate with radio transmitters and receivers which are adapted to a sudden frequency change, in order to render any recognition of the carrier frequency and thus interception by the enemy substantially more difficult. Since any direct transmission of intelli-gence or radio determination will generally be necessaryonlyinalow percentage of all cases, it is suggested by the present invention that in the remaining time Oe transmission of intelligence, or of radio determination-~ each of one~s own stations, the transmitter of each station is additionally operated as a jamming transmitter. Since the pattern of frequency change has been established for the entire combat unit according to the area of Figure 1, it is possible to carry out effective jamming, including spot jamming, on any ..~.
~, ~
lZ'1)3~'76 frequency outside or inside of one's own frequency range. However, it is advisable to group the individual communications channels, which may be rapid-ly changed inter se, to form sub-ranges so that a plurality of channels of adjacent frequency can be covered by one wide bandpass filter. It is thus advisable to divide all of the channels available into sub-ranges of this kind so that it will be possible at any time to produce effective barrage jamming on any sub-ranges which are not used at the time. Wobbling, barrage, or selective jamming may be applied. It is advisable, however, to use barrage jamming, as the enemy's intelligence transmission channels will generally not be known. Transmission may be made in a frequency range of from 225 to 400 M~lz, as this is the range, in which the mobile radio and directional radio networks are generally operated. When the band is combined with units of a width of 20 M~lz, for example, even these high carrier frequencies permit the production of relatively simple filters which can select the individual bands.
Figure 2 shows the construction of the transmitter in principle.
STG defines the jamming unit and NG the information signal unit (generator).
A switch Sl connects with a power amplifier LV and the switch S2 at the out-put side of the amplifier transmits the amplified signal onto a bandpass filter Bl and subsequently to an information signal antenna Na, or to a 2Q bandpass filter B2 for the jamming signal and possibly to a jamming antenna SA
o~ greater band width. A common control unit STE controls both switches Sl and S2 synchronously and - as stated before - dependent on whether one's own transmitter for the transmission of intelligence or position finding is or is not used at that point in time. Instead of the aforestated two filters Bl and B2, it is certainly possible to use a plurality of switchable filters. This may be controlled by a separate control unit which has not been included in the drawing. In the programme, the control units must be advised in what frequency sub-ranges at what time a transmission of intelligence or radio determination of one's own is carried out. The switching unit for the control of a plurality of bandpasses, for example, will for its functioning in each ~l2~35~i case be provided at the outlet side of the control unit STE.
Figure 3 shows a circuit diagram with further details concerning a transmitting and receiving station according to Figure 2. The block circuit diagram has for reasons of simplification been restricted to the representation of the assemblies in the intermediate frequency and radio frequency range, including the frequency processing. On the transmission side, the signal produced is passed in the intermediate frequency range to the converter SU on the transmission side which on its output side is connected with one switch-over contact of the switch Sl. The common connection of the switch Sl is connected with the input of the power amplifier LV which, in turn, is connect-ed on its outlet side with the common contact of the switch S2. One of the switch-over contacts of the switch S2 is connected with the input of the bandpass Bl which is disposed at the input side of the diplexer Dl. The output of the diplexer is connected with the antenna NA. A signal received by this antenna is passed to the receiver CF modulator EU, with which the receiving amplifier in the intermediate frequency position is connected. In the illus-trated position of the switch Sl the transposer on the transmitter side is connected to the power amplifier LV. In the second switching position, shown in interrupted line, the input of the power amplifier is connected with the output of the synthesizer SYN, where the jamming signal is prepared. The synthesizer is controlled by the computer CP which cooperates with the coding device Sch' and is controlled by a quartz clock Q. The switches Sl and S2 are jointly controlled by the control device STE so that when the switch Sl is switched into the position illustrated in interrupted line, the switch S2 is likewise placed in the switching position shown in interrupted line. In this position, the output of the power amplifier is connected with the jamming antenna SA via the bandpass B2. The frequency to be prepared for the trans-poser on the input and on the output side takes place in a further synthesizer SYN. It is controlled by the further computer CP, being provided with a coding device Sch, through the adder AD, to the second input of which the 135~
locations AS of the participating parties are passed. These locations AS are likewise passed to th~ control input of the control device STE. The further computer CP is controlled by the quartz clock Q in the same mannerO The synthesizer SYN, the computer CP, the coding devices Sch and Sch' as well as the adder AD are jointly supplied with pulses of the pulse source T. With regard to the coding device Sch, programming is carried out in anti-cycle ashion so that in the absence of information-signal operation the jamming signal generator will emit only frequencies in frequency ranges which are not used for the transmission of information signals at that time. When a location AS of a participating party has been received, the control device STE places the switches Sl, S2 into the position shown in Figure 3, wherein the jamming transmi~ter is switched off. In casethere is no location of a participating party available, i.e. in those time intervals where ~e data ~ information signals are exchanged, the control device places the switches Sl and S2 into the position illustrated in the Figure in interrupted line and thus releases a radio interference.
In this fashion it is possible to highly efficiently carry Ollt ECM, directly in the proximity zone, at relatively low transmitting power, as is generally used in small-size radio stations. It is possible to make use of the aforestated advantages for one's own communications work and for jamming. Any specific reaction by the enemy is rendered practically impossible, because the stations do not principally expose themselves by their ECM
activity any more than necessary by their military mission which carries them into the proximity of the enemy's zone of radio operation.
_ 5 _ .~ .1 -
Systems operating with methods of sudden frequency changes have become known from United States Patent 3,426,279, for example. In these systems a leaping change in operating frequencies is carried out in accordance with a predetermined pattern, of which all stations participating in the communic-ations activity are aware. This pattern may he stored, for example, for a period of time, such as a day, in an on board computer. On board computer systems of this kind generally form part of the cryptological equipment and do not require any substantial additional resources for solving any further tasks. In principle, these aspects likewise apply to position-fixing.
It is the object of the present invention, to carry out in a frequency-changing system of the aforestated kind effective jamming of an enemy's transmission oE intelligence, without interfering with one's own transmission.
According to the present invention, there is provided a method of operating a military radar or radio communications system having a plurality of stations each having a transmitter and receiver, said method comprising using rapidly changed frequencies within a sub-band of a plurality of sub-bands oE
available frequencies for transmitting and receiving information signals and using any of the transmitters which are not engaged in transmitting information signals to transmit jamming signals on the sub-bands not then being used to transmit information . . ~ 1 -~;Z V3~6 signals, and changing at controlled time intervals the sub-band in which information signals are transmitted and received and the remaining sub-bands on which jamming signals are trans-mitted.
This offers a highly effective opportunity to use ECM (Electronic Counter Measures), especially in the area of operation, where a great effect can be achieved without great transmitter power. This applies in particular to those systems operating with a central and thus remote jamming station - la -~2~1~3~
which cannot be operated in the intermediate vicinity of the area of operation and which would be much easier to detect by the enemy's defence. In mobile stations, which are expected to operate in the front area, such as tanks or missiles, the locating of the enemy is of secondary importance, because the vehicles or missiles have to expose themselves by nature.
It is possible with the aid of relatively low transmitt0r power to effectively interfere with an enemy's intelligence or position-finding system, without principally shortchanging one's own transmission of intelli-gence or radio determination.
The present invention will be further discussed below with the aid of three Figures as follows:
Figure 1 is a schematic diagram of a system according to the invention.
Figure 2 is a block diagram of a transmitter.
Figure 3 is a detailed block diagram of a transmitting and receiv-ing station.
Figure 1 defines an area by means of a rectangle, where a plural-ity of vehicle stations T of one's own and G of the enemy's radio stations are located. These radio stations are generally mobile, for example tank units.
As stated above, these stations operate with radio transmitters and receivers which are adapted to a sudden frequency change, in order to render any recognition of the carrier frequency and thus interception by the enemy substantially more difficult. Since any direct transmission of intelli-gence or radio determination will generally be necessaryonlyinalow percentage of all cases, it is suggested by the present invention that in the remaining time Oe transmission of intelligence, or of radio determination-~ each of one~s own stations, the transmitter of each station is additionally operated as a jamming transmitter. Since the pattern of frequency change has been established for the entire combat unit according to the area of Figure 1, it is possible to carry out effective jamming, including spot jamming, on any ..~.
~, ~
lZ'1)3~'76 frequency outside or inside of one's own frequency range. However, it is advisable to group the individual communications channels, which may be rapid-ly changed inter se, to form sub-ranges so that a plurality of channels of adjacent frequency can be covered by one wide bandpass filter. It is thus advisable to divide all of the channels available into sub-ranges of this kind so that it will be possible at any time to produce effective barrage jamming on any sub-ranges which are not used at the time. Wobbling, barrage, or selective jamming may be applied. It is advisable, however, to use barrage jamming, as the enemy's intelligence transmission channels will generally not be known. Transmission may be made in a frequency range of from 225 to 400 M~lz, as this is the range, in which the mobile radio and directional radio networks are generally operated. When the band is combined with units of a width of 20 M~lz, for example, even these high carrier frequencies permit the production of relatively simple filters which can select the individual bands.
Figure 2 shows the construction of the transmitter in principle.
STG defines the jamming unit and NG the information signal unit (generator).
A switch Sl connects with a power amplifier LV and the switch S2 at the out-put side of the amplifier transmits the amplified signal onto a bandpass filter Bl and subsequently to an information signal antenna Na, or to a 2Q bandpass filter B2 for the jamming signal and possibly to a jamming antenna SA
o~ greater band width. A common control unit STE controls both switches Sl and S2 synchronously and - as stated before - dependent on whether one's own transmitter for the transmission of intelligence or position finding is or is not used at that point in time. Instead of the aforestated two filters Bl and B2, it is certainly possible to use a plurality of switchable filters. This may be controlled by a separate control unit which has not been included in the drawing. In the programme, the control units must be advised in what frequency sub-ranges at what time a transmission of intelligence or radio determination of one's own is carried out. The switching unit for the control of a plurality of bandpasses, for example, will for its functioning in each ~l2~35~i case be provided at the outlet side of the control unit STE.
Figure 3 shows a circuit diagram with further details concerning a transmitting and receiving station according to Figure 2. The block circuit diagram has for reasons of simplification been restricted to the representation of the assemblies in the intermediate frequency and radio frequency range, including the frequency processing. On the transmission side, the signal produced is passed in the intermediate frequency range to the converter SU on the transmission side which on its output side is connected with one switch-over contact of the switch Sl. The common connection of the switch Sl is connected with the input of the power amplifier LV which, in turn, is connect-ed on its outlet side with the common contact of the switch S2. One of the switch-over contacts of the switch S2 is connected with the input of the bandpass Bl which is disposed at the input side of the diplexer Dl. The output of the diplexer is connected with the antenna NA. A signal received by this antenna is passed to the receiver CF modulator EU, with which the receiving amplifier in the intermediate frequency position is connected. In the illus-trated position of the switch Sl the transposer on the transmitter side is connected to the power amplifier LV. In the second switching position, shown in interrupted line, the input of the power amplifier is connected with the output of the synthesizer SYN, where the jamming signal is prepared. The synthesizer is controlled by the computer CP which cooperates with the coding device Sch' and is controlled by a quartz clock Q. The switches Sl and S2 are jointly controlled by the control device STE so that when the switch Sl is switched into the position illustrated in interrupted line, the switch S2 is likewise placed in the switching position shown in interrupted line. In this position, the output of the power amplifier is connected with the jamming antenna SA via the bandpass B2. The frequency to be prepared for the trans-poser on the input and on the output side takes place in a further synthesizer SYN. It is controlled by the further computer CP, being provided with a coding device Sch, through the adder AD, to the second input of which the 135~
locations AS of the participating parties are passed. These locations AS are likewise passed to th~ control input of the control device STE. The further computer CP is controlled by the quartz clock Q in the same mannerO The synthesizer SYN, the computer CP, the coding devices Sch and Sch' as well as the adder AD are jointly supplied with pulses of the pulse source T. With regard to the coding device Sch, programming is carried out in anti-cycle ashion so that in the absence of information-signal operation the jamming signal generator will emit only frequencies in frequency ranges which are not used for the transmission of information signals at that time. When a location AS of a participating party has been received, the control device STE places the switches Sl, S2 into the position shown in Figure 3, wherein the jamming transmi~ter is switched off. In casethere is no location of a participating party available, i.e. in those time intervals where ~e data ~ information signals are exchanged, the control device places the switches Sl and S2 into the position illustrated in the Figure in interrupted line and thus releases a radio interference.
In this fashion it is possible to highly efficiently carry Ollt ECM, directly in the proximity zone, at relatively low transmitting power, as is generally used in small-size radio stations. It is possible to make use of the aforestated advantages for one's own communications work and for jamming. Any specific reaction by the enemy is rendered practically impossible, because the stations do not principally expose themselves by their ECM
activity any more than necessary by their military mission which carries them into the proximity of the enemy's zone of radio operation.
_ 5 _ .~ .1 -
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of operating a military radar- or radio com-munications system having a plurality of stations each having a transmitter and receiver, said method comprising using rapidly changed frequencies within a sub-band of a plurality of sub-bands of available frequencies for transmitting and receiving information signals and using any of the transmitters which are not engaged in transmitting information signals to transmit jamming signals on the sub-bands not then being used to transmit information signals, and changing at controlled time intervals the sub-band in which information signals are transmitted and received and the remaining sub-bands on which jamming signals are transmitted.
2. A military radar- or radio communications system for carrying out the method according to claim 1, characterized in that in each transmitter a common power-output stage is provided with a current supply which on its input side is alternately connected to a control generator modulated by information signals and to a jamming signal generator, and which on its output side is adapted to be connected to correspond-ingly arranged antennas through switchable filters which are adapted to respective frequencies or frequency bands for the transmission of information signals or jamming signals.
3. A method according to claim 1, characterized in that the changing of sub-bands for information signals and jamming signals is carried out in accordance with a time-wise synchronized frequency-changing programme in all participating stations, where the programme is stored in each station and is available to a computer at each said station.
4. A military radar- or radio communications trans-mission system according to claim 2, characterized in that the changing of sub-bands for information signals and jamming signals is carried out in accordance with a time-wise synchro-nized frequency-changing programme in all participating stations, where the programme is stored in each station and is available to a computer at each said station.
5. A military radar- or radio communications trans-mission system according to claim 4, characterized in that the frequency-changing programme is coordinated with a programme for a transfer device for sudden frequency change and both pro-grammes are processed by a common computer.
6. A military radar- or radio communications trans-mission system according to claim 2 or 5, characterized in that the frequency sub-bands are arranged in such a manner that they can be decoupled by relatively simple selection means at the transmitter and at the receiver end as well as at the jamming signal generator.
7. A system according to claim 2 wherein the alternate connections are effected under programme control.
8. A system according to claim 2 wherein the alternate connections are controlled by a central station.
9. A system according to claim 4 or 5 where the frequency-changing programme is effective for a relatively long period of time.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2737577.5 | 1977-08-22 | ||
| DE2737577A DE2737577C1 (en) | 1977-08-22 | 1977-08-22 | Military radar or radio communications system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1203576A true CA1203576A (en) | 1986-04-22 |
Family
ID=6016865
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000307208A Expired CA1203576A (en) | 1977-08-22 | 1978-07-12 | Military radar - or radio communications transmission system |
Country Status (7)
| Country | Link |
|---|---|
| BE (1) | BE867291A (en) |
| CA (1) | CA1203576A (en) |
| DE (1) | DE2737577C1 (en) |
| FR (1) | FR2573216A1 (en) |
| IT (1) | IT1096808B (en) |
| NL (1) | NL177962C (en) |
| NO (1) | NO782846L (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0562868A2 (en) * | 1992-03-27 | 1993-09-29 | WI-LAN Inc | Method and apparatus for multiple access between transceivers in wireless communication using OFDM spread spectrum |
| US6192068B1 (en) | 1996-10-03 | 2001-02-20 | Wi-Lan Inc. | Multicode spread spectrum communications system |
| USRE37802E1 (en) | 1992-03-31 | 2002-07-23 | Wi-Lan Inc. | Multicode direct sequence spread spectrum |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2830710B1 (en) * | 2001-10-09 | 2004-02-27 | Thales Sa | INTERFERENCE METHOD AND SYSTEM |
| GR1004549B (en) * | 2001-12-04 | 2004-05-11 | Νικολαος Ουζουνογλου | Electronic countermeasure system jamming enemy frequency hopping communication wireless networks and in parallel protecting friendly networks |
| DE10318475A1 (en) | 2003-04-23 | 2004-11-25 | Rheinmetall W & M Gmbh | Procedure for trouble-free communication when operating a jammer |
| DE102011113644A1 (en) | 2011-09-19 | 2013-03-21 | Rheinmetall Soldier Electronics Gmbh | Device for identification and communication |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1462279A (en) * | 1965-09-21 | 1966-04-15 | Cit Alcatel | Random carrier frequency radio links |
| DE1954754C3 (en) * | 1969-10-30 | 1975-08-07 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Radio telephony system that works with encryption of the message signals to be transmitted |
| CH559483A5 (en) * | 1973-06-12 | 1975-02-28 | Patelhold Patentverwertung |
-
1977
- 1977-08-22 DE DE2737577A patent/DE2737577C1/en not_active Expired
-
1978
- 1978-05-19 BE BE187884A patent/BE867291A/en unknown
- 1978-06-22 IT IT24820/78A patent/IT1096808B/en active
- 1978-07-12 CA CA000307208A patent/CA1203576A/en not_active Expired
- 1978-08-17 NL NLAANVRAGE7808533,A patent/NL177962C/en not_active IP Right Cessation
- 1978-08-21 NO NO782846A patent/NO782846L/en unknown
- 1978-08-21 FR FR7824268A patent/FR2573216A1/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0562868A2 (en) * | 1992-03-27 | 1993-09-29 | WI-LAN Inc | Method and apparatus for multiple access between transceivers in wireless communication using OFDM spread spectrum |
| EP0562868A3 (en) * | 1992-03-27 | 1994-07-06 | Wi Lan Inc | Method and apparatus for multiple access between tansceivers in wireless communication using OFDM spread spectrum. |
| USRE37802E1 (en) | 1992-03-31 | 2002-07-23 | Wi-Lan Inc. | Multicode direct sequence spread spectrum |
| US6192068B1 (en) | 1996-10-03 | 2001-02-20 | Wi-Lan Inc. | Multicode spread spectrum communications system |
| US6320897B1 (en) | 1996-10-03 | 2001-11-20 | Wi-Lan Inc. | Multicode spread spectrum communications system |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2573216A1 (en) | 1986-05-16 |
| DE2737577C1 (en) | 1986-01-09 |
| NO113576C (en) | 1986-03-12 |
| IT7824820A0 (en) | 1978-06-22 |
| NL177962C (en) | 1985-12-16 |
| IT1096808B (en) | 1985-08-26 |
| BE867291A (en) | 1985-06-10 |
| NO782846L (en) | 1986-07-30 |
| NL177962B (en) | 1985-07-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |