EP0084967A2 - Système de communication par radio - Google Patents

Système de communication par radio Download PDF

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Publication number
EP0084967A2
EP0084967A2 EP83300320A EP83300320A EP0084967A2 EP 0084967 A2 EP0084967 A2 EP 0084967A2 EP 83300320 A EP83300320 A EP 83300320A EP 83300320 A EP83300320 A EP 83300320A EP 0084967 A2 EP0084967 A2 EP 0084967A2
Authority
EP
European Patent Office
Prior art keywords
radio
sequence
frequency
sets
random number
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.)
Granted
Application number
EP83300320A
Other languages
German (de)
English (en)
Other versions
EP0084967A3 (en
EP0084967B1 (fr
Inventor
Paul Wilkinson Dent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Electronics Ltd
Original Assignee
Marconi Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Marconi Co Ltd filed Critical Marconi Co Ltd
Priority to AT83300320T priority Critical patent/ATE13789T1/de
Publication of EP0084967A2 publication Critical patent/EP0084967A2/fr
Publication of EP0084967A3 publication Critical patent/EP0084967A3/en
Application granted granted Critical
Publication of EP0084967B1 publication Critical patent/EP0084967B1/fr
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00—Secret communication
    • H04K1/003—Secret communication by varying carrier frequency at or within predetermined or random intervals

Definitions

  • This invention relates to radio communication apparatus and particularly to such apparatus in which the carrier frequency is changed periodically in an attempt to maintain security and overcome jamming of the radio transmission.
  • Such periodic frequency cheanging is called hopping.
  • Each radio set in the network may be adapted to operate on a common hop-set according to its own pseudo-random sequence thus giving what is called a random hopping system.
  • a random hopping system In this system, statistically predictable interference occurs as a result of random frequency coincidences when two communications are being conducted simultaneously.
  • UK Patent Applicaion Serial No. 2103052 describes a random frequency hopping system in which such random interference is avoided without serious damage to the transmission.
  • crthogonal is one in which both the hop-set and the pseudo-random sequence is common to each radio set in the network. Some means then has to be employed to prevent continuous interference between the channels used in simultaneous communications. Such a system is described in UK Patent Application Serial No. 2101847.
  • An object of the present invention is to provide a random frequency hopping system which permits simultaneous non-interfering conversations in a radio network.
  • a frequency-hopping radio communication system comprises a plurality of radio transmitter/receiver sets having means for changing their operating frequencies periodically, in synchronism, and according to a common main-line pseudo-random channel sequence, each radio set having means for modifying its operating channel sequence to a side track sequence dependent upon the point in said main line sequence at which the modification is initiated and means for transmitting a signal to a selected other radio set to initiate said side track sequence in the receiving radio set at the sane instant as in the transmitting radio set, both radio sets being arranged to revert to the main-line channel secuence on termination of the transmission.
  • the modification may be effected by a change in a feedback path of a pseudo-random number generator in each radio set which generator determines the operating channel sequence of the radio set.
  • a real time clock 1 steps a random number generator 2 through a pseudo random number sequence, the output number at any instant being determined by the original number, i.e. the key variable, with which the random number generator was loaded, and the time elapsed since that occurrence.
  • All radio sets in the network are loaded with the same key variable and their clocks are initially synchronised, so that all radio sets will produce the same pseudo-random number sequence in synchronism. There may be a very slight phase drift between the number sequences of the different radio sets if they should run on for a substantial time without communication but this is accommodated as will be seen.
  • Each radio set has a stored table 3 of permitted frequencies, i.e. a large random selection of the total possible channels in the band. This hop-set is again common to all radios of the network.
  • the table 3 is addressed by each multi-digit random number as it arises and the resulting channel frequency identity is applied to a transmitter/receiver radio 14 which is frequency agile and electronically tunable.
  • the operating frequency thus changes periodically and synchronously for all radios of the network in accordance with the number sequence provided by a number generator. This common basic sequence will be referred to as the main-line sequence.
  • the key variable initially loaded into each random number generator 2 can be changed periodically for different networks on a geographical or other basis.
  • the random number generator 2 consists of a shift register with predetermined feedback in known manner.
  • a controllable feedback path 4 which, when effective, charges the pattern generated in a predetermined manner.
  • This feedback path is controlled by a switch 6, the modified number sequence produced by the generator then depending upon the content of the generator when the modification is initiated.
  • a bistable 8 determines the condition of the switch 6, the switch being closed when the bistable is 'set'.
  • an absolute time marker is transmitted, a so-called 'bingo' signal. It is the transmission and reception of this signal which initiates the modification of the random number generator 2 in the transmitting and receiving radios.
  • the bistable 8 has a set input derived by way of an OR-gate 10 from a 'bingo' detector 12 which monitors the signal received by the basic radio 14. Immediately therefore, on reception of the 'bingo' signal the bistable 8 is set, the switch 6 is closed, and a modified random number sequence is generated dependent upon the content of the generator at the instant of switch closure. At the transmitting radio the bistable 8 is set at the same instant by a signal following the synchronising and addressing preamble. This post-transmission synchronising signal is applied by way of the OR-gate 10.
  • Both transmitting and receiving radios are thus modified at the same instant and with the same content in their random number generators.
  • the resulting modified sequences which bear no relation to the main-line sequence, are therefore identical and communication can proceed between these two radios. If, of course, transmission to two or more other radios is required this is easily accommodated, by transmission of the respective addresses on the main line sequence.
  • Figure 2 shows the effect of closure of the switch 6 on the operating frequency sequences.
  • the upper horizontal line indicates the main-line frequency sequence F5 F18 F6 etc ( a typical part of the sequence), the frequency changes occurring at regular intervals determined by the clock. If, for example radio 1 calls radio 2, and the 'bingo' signal arises at the instant of the main-line change to F 4 , then a sidetrack sequence will occur in radios 1 & 2 having typical frequencies F 15 F 10 F 3 etc as shown. These latter changes will occur in synchronism with the main-line changes F 1 F 3 F 10 etc. Radios 1 & 2 will then operate on the modified or sidetrack sequence while the remainder of the radios in the network carry on passively on the main-line sequence.
  • radio 3 should call radio 4 and emit a 'bingo' signal at F 12 in the main-line sequence then the content of the random number generators of radios 3 & 4 will at that instant be different from the content of the generators of radios 1 & 2 and consequently a new sidetrack sequence will arise for the operation of radios 3 & 4. No interference between the two communications will arise other than the predictable statistical coincidence of frequencies. As mentioned previously, the system described in Patent Application No. 8119215 will alleviate any troubles arising from this cause.
  • an 'end-of-message' code is transmitted, which is detected by a detector 16.
  • An output from the detector 16 resets the bistable 8 by way of an OR-gate 18, the switch 6 opens, and the generator 2 reverts to the production of the main-line sequence in the same phase as if it had not been interrupted.
  • a transmit key input 20 also serves to reset the bistable 8 by way of OR-gate 18 to ensure that on transmission the radio is operating on the main-line sequence i.e. on which all other (passive) radios are listening for their address code.
  • the system described has the significant feature, in contrast with fixed frequency radio systems, that an ongoing selective communication does not prevent the rest of the net communicating, or setting up selective calls of their own, since the sequence of frequencies used to set up calls, the main line sequence, is unrelated to the sequence of frequencies used for the message, the side- track sequence. Furthermore, there are as many different sidetrack sequences as there are points of departure from the main line sequence, the only limiting factor to their use being the acceptability of interference caused by the statistical probability that two or more sequences will alight on the same frequency at the same time.
  • the main-line sequence could be rendered unavailable to a large extent by constantly switching a captured radio between transmit and receive.
  • Software or hardware traps may be built into the radio to prevent a captured radio being switched in this way. Such a trap may for instance cause erasure of the key variable upon detection of such behaviour.
  • a captured radio may, of course, be modified by the enemy to bypass these traps; but that would involve laboratory work, and by the time the radio was returned to the field, the key variable would no longer be current. It may also be made extremely difficult to extract the key variable from one radio in order to transfer it to a modified radio.
  • retransmission is often employed, whereby the signal is received from the initiating transmitter on one frequency, and relayed on another frequency.
  • Two conventional radio sets may be connected back-to-back to provide such an automatic relay station, as illustrated diagrammatically in Figure 3.
  • single frequency simplex is used on each leg of the path, and the relaying transmitter is keyed only when the receiver detects the presence of a valid signal. Since the two legs of the relay path must be on different frequencies to provide adequate isolation between the co-sited transmitter and receiver, the frequency on which a receiving station should best listen depends on its geographical position, i.e., whether it is nearer to the initiating station or the appropriate relay site.
  • a mobile station may have to change frequency according to position.
  • the relay station may comprise two radio sets B & C each as aforesaid but modified in that set B is made receptive to all transmissions irrespective of address, any valid transmission so received on the main line sequence causing conversion to a sidetrack sequence at the BINGO code reception.
  • the first radio link in the relay process, . between the originating station A and the relay station B/C is then operated on a first side track sequence. un such valid reception the transmitting set C of the relay station is caused to initiate re-transmission on the main line sequence, of the synchronising and address preamble, the address being that of the out-station D, relayed from the originating station A.
  • both set C and out-station set D switch to a side-track sequence which is different from that in operation between the AB link since it arisee at a later time. There is again, therefore, no interference between the AB transmission and the CD tranemission.
  • Bets A & D are interchanged and the operation proceeds exactly as before.
  • the mobile radio set D will lock onto the firat synchronisation preamble which it receives successfully whether from the initiating station A or the relay statice B/C. As it moves out of range of one relay site and into the coverage zone of another, no action is thus required by the operator to pick up the new relay link.
EP83300320A 1982-01-27 1983-01-21 Système de communication par radio Expired EP0084967B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83300320T ATE13789T1 (de) 1982-01-27 1983-01-21 Funkverbindungssystem.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8202357 1982-01-27
GB8202357 1982-01-27

Publications (3)

Publication Number Publication Date
EP0084967A2 true EP0084967A2 (fr) 1983-08-03
EP0084967A3 EP0084967A3 (en) 1983-08-10
EP0084967B1 EP0084967B1 (fr) 1985-06-12

Family

ID=10527920

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83300320A Expired EP0084967B1 (fr) 1982-01-27 1983-01-21 Système de communication par radio

Country Status (7)

Country Link
EP (1) EP0084967B1 (fr)
JP (1) JPS58161438A (fr)
AT (1) ATE13789T1 (fr)
AU (1) AU553652B2 (fr)
DE (1) DE3360246D1 (fr)
GB (1) GB2114402B (fr)
IN (1) IN159180B (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0247790A2 (fr) * 1986-05-27 1987-12-02 Fairchild Weston Systems Inc. Système de communication sécurisé pour plusieurs unités éloignées
EP0476129A1 (fr) * 1990-04-04 1992-03-25 LUND, Van Metre Systeme de communication
EP0667695A4 (fr) * 1991-08-23 1995-05-29 Toshiba Kk Systeme d'informations et de communications radio mettant en uvre un systeme de transmission a porteuses multiples et a etalement du spectre.
EP0711057A2 (fr) * 1994-11-03 1996-05-08 AT&T Corp. Téléphone sans fil opérant avec plusieurs unités portables dans un système de communication à évasion de fréquence
US5533046A (en) * 1992-10-08 1996-07-02 Lund; Vanmetre Spread spectrum communication system
EP0741464A2 (fr) * 1995-05-02 1996-11-06 Plessey Semiconductors Limited Synchronisation des postes émetteurs-récepteurs dans un réseau local sans fil fonctionnant en évasion de fréquence
WO1999009668A1 (fr) * 1997-08-14 1999-02-25 Siemens Aktiengesellschaft Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile
WO1999066653A1 (fr) * 1998-06-18 1999-12-23 Siemens Aktiengesellschaft Procede et dispositif permettant de convertir une sequence de nombres aleatoires en frequences porteuses pour une radiotransmission mobile
EP0691775A3 (fr) * 1994-07-05 2000-08-23 AT&T Corp. Appareil et méthode de configuration d'un téléphone sans fil pour l'utiliser dans un système de communication à évasion de fréquence
WO2001097588A2 (fr) * 2000-04-18 2001-12-27 Sun Microsystems, Inc. Maitrise d'acces a une information sur un reseau multibandes

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2129655B (en) * 1982-09-08 1986-02-05 Racal Res Ltd Improvements in and relating to radio communications
WO1993021703A1 (fr) * 1992-04-15 1993-10-28 Coachline Video Express Pty Ltd Systeme de distribution de signaux
GB2300547B (en) * 1995-05-02 1999-08-25 Plessey Semiconductors Ltd Wireless local area neworks
GB9513398D0 (en) * 1995-06-30 1995-09-27 Boateng Jacob K Automatic exchangeless universal radio phone
WO2020261403A1 (fr) * 2019-06-26 2020-12-30 日本電気株式会社 Dispositif ainsi que procédé d'estimation de taille, et support non-temporaire lisible par ordinateur stockant un programme
JP7396364B2 (ja) * 2019-10-31 2023-12-12 日本電気株式会社 画像処理装置、画像処理方法及び画像処理プログラム
JP7355674B2 (ja) 2020-02-18 2023-10-03 株式会社日立製作所 映像監視システムおよび映像監視方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1939975A1 (de) * 1969-08-06 1971-02-18 Licentia Gmbh System zur UEbertragung von binaercodierten Nachrichten
US3584303A (en) * 1968-02-12 1971-06-08 Patelhold Patentverwertung Step-by-step frequency wobbled and address-coded transmission system
GB1536868A (en) * 1974-12-03 1978-12-20 Licentia Gmbh Method for setting up a quasi-random generator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3584303A (en) * 1968-02-12 1971-06-08 Patelhold Patentverwertung Step-by-step frequency wobbled and address-coded transmission system
DE1939975A1 (de) * 1969-08-06 1971-02-18 Licentia Gmbh System zur UEbertragung von binaercodierten Nachrichten
GB1536868A (en) * 1974-12-03 1978-12-20 Licentia Gmbh Method for setting up a quasi-random generator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IEE PROCEEDINGS SECTION A-K, vol. 129, no. 3, part F, June 1982, pages 213-222, Old Woking, Surrey, GB. *

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0247790A2 (fr) * 1986-05-27 1987-12-02 Fairchild Weston Systems Inc. Système de communication sécurisé pour plusieurs unités éloignées
EP0247790A3 (fr) * 1986-05-27 1989-02-08 Fairchild Weston Systems Inc. Système de communication sécurisé pour plusieurs unités éloignées
EP0476129A1 (fr) * 1990-04-04 1992-03-25 LUND, Van Metre Systeme de communication
EP0476129A4 (en) * 1990-04-04 1993-08-11 Van Metre Lund Communication system
USRE34831E (en) * 1990-04-04 1995-01-17 Lund; Van Metre Communication system
EP0667695A4 (fr) * 1991-08-23 1995-05-29 Toshiba Kk Systeme d'informations et de communications radio mettant en uvre un systeme de transmission a porteuses multiples et a etalement du spectre.
EP0667695A1 (fr) * 1991-08-23 1995-08-16 Kabushiki Kaisha Toshiba Systeme d'informations et de communications radio mettant en uvre un systeme de transmission a porteuses multiples et a etalement du spectre
US5561686A (en) * 1991-08-23 1996-10-01 Kabushiki Kaisha Toshiba Radio information communication system using multi-carrier spread spectrum transmission system
US5533046A (en) * 1992-10-08 1996-07-02 Lund; Vanmetre Spread spectrum communication system
EP0691775A3 (fr) * 1994-07-05 2000-08-23 AT&T Corp. Appareil et méthode de configuration d'un téléphone sans fil pour l'utiliser dans un système de communication à évasion de fréquence
EP0711057A2 (fr) * 1994-11-03 1996-05-08 AT&T Corp. Téléphone sans fil opérant avec plusieurs unités portables dans un système de communication à évasion de fréquence
EP0711057A3 (fr) * 1994-11-03 2000-08-30 AT&T Corp. Téléphone sans fil opérant avec plusieurs unités portables dans un système de communication à évasion de fréquence
EP0741464A2 (fr) * 1995-05-02 1996-11-06 Plessey Semiconductors Limited Synchronisation des postes émetteurs-récepteurs dans un réseau local sans fil fonctionnant en évasion de fréquence
EP0741464A3 (fr) * 1995-05-02 2000-08-02 Mitel Semiconductor Limited Synchronisation des postes émetteurs-récepteurs dans un réseau local sans fil fonctionnant en évasion de fréquence
WO1999009668A1 (fr) * 1997-08-14 1999-02-25 Siemens Aktiengesellschaft Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile
EP1002375A1 (fr) * 1997-08-14 2000-05-24 Siemens Aktiengesellschaft Procede et dispositif de production d'une sequence de nombres aleatoires pour des frequences porteuses dans une transmission en radiotelephonie mobile
WO1999066653A1 (fr) * 1998-06-18 1999-12-23 Siemens Aktiengesellschaft Procede et dispositif permettant de convertir une sequence de nombres aleatoires en frequences porteuses pour une radiotransmission mobile
WO2001097588A2 (fr) * 2000-04-18 2001-12-27 Sun Microsystems, Inc. Maitrise d'acces a une information sur un reseau multibandes
WO2001097588A3 (fr) * 2000-04-18 2002-05-16 Sun Microsystems Inc Maitrise d'acces a une information sur un reseau multibandes

Also Published As

Publication number Publication date
JPS58161438A (ja) 1983-09-26
JPH0234499B2 (fr) 1990-08-03
EP0084967A3 (en) 1983-08-10
AU553652B2 (en) 1986-07-24
GB2114402A (en) 1983-08-17
IN159180B (fr) 1987-04-04
DE3360246D1 (en) 1985-07-18
AU1062383A (en) 1983-08-04
ATE13789T1 (de) 1985-06-15
GB2114402B (en) 1985-06-05
EP0084967B1 (fr) 1985-06-12

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