| Patents for H04K 1 - Secret communication (16,771) |
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| 02/26/1992 | CN1059058A Authentication system for digital cellular communications |
| 02/25/1992 | US5091942 Authentication system for digital cellular communications |
| 02/25/1992 | US5091941 Secure voice data transmission system |
| 02/25/1992 | US5091938 System and method for transmitting entertainment information to authorized ones of plural receivers |
| 02/25/1992 | US5091936 System for communicating television signals or a plurality of digital audio signals in a standard television line allocation |
| 02/11/1992 | CA1295686C Time domain radio transmission system |
| 02/05/1992 | EP0469989A1 Method for protection against non-authorized descrambling of scrambled television transmissions and apparatus therefor |
| 02/05/1992 | EP0469106A1 Video signal scrambling and unscrambling device. |
| 02/05/1992 | EP0382764A4 Signal processing apparatus and methods |
| 01/24/1992 | WO1992002087A1 Authentication system for digital cellular communications |
| 01/09/1992 | DE4021061A1 Coded protection for transmitted facsimile data - subjecting line scanned data to bit shifting to maintain confidentiality |
| 12/31/1991 | US5077791 Method and apparatus for preventing unauthorized transmissions |
| 12/31/1991 | CA1293785C Secure communication system |
| 12/26/1991 | WO1991020145A1 Signal acquisition |
| 12/11/1991 | EP0461029A1 Trans-controller method and device for installation and distribution of television programmes with conditional access |
| 12/03/1991 | CA1292778C Digital radio with security system for selectively enabling software controlled options |
| 11/21/1991 | EP0457602A2 Data security in multi-carrier communication systems |
| 11/12/1991 | US5065430 Voice band splitting scrambler |
| 11/05/1991 | CA1291833C Voice band splitting scrambler |
| 10/29/1991 | CA1291559C Method for coding and de-coding informations and apparatus for the working thereof |
| 10/15/1991 | US5058159 Method and system for scrambling and descrambling audio information signals |
| 10/15/1991 | US5058157 Method and apparatus for encrypting and decrypting time domain signals |
| 10/11/1991 | WO1991015910A1 Method of synchronising the pseudo-random binary sequence in a descrambler |
| 10/08/1991 | US5056137 Method and apparatus for encoding and decoding signals |
| 10/08/1991 | US5055845 Signal digitizing method and system utilizing time delay of the input signal |
| 09/25/1991 | EP0448534A2 Method and apparatus for encryption/decryption of digital multisound in television |
| 09/24/1991 | US5051991 Method and apparatus for efficient digital time delay compensation in compressed bandwidth signal processing |
| 09/24/1991 | CA2038916A1 Method and apparatus for encryption/decryption of digital multisound in television |
| 09/18/1991 | EP0446280A1 Off-premises cable television channel interdiction method and apparatus. |
| 09/11/1991 | EP0377687A4 Spectrally efficient method for communicating an information signal |
| 09/05/1991 | WO1991013517A1 Video signal scrambling and unscrambling device |
| 08/29/1991 | WO1991013498A1 Hole placement and fill system based on category selection |
| 08/27/1991 | CA1288182C Secret speech equipment |
| 08/17/1991 | WO1991012679A1 Method and apparatus for providing privacy/security in a communications system |
| 08/17/1991 | CA2073454A1 Method and apparatus for providing privacy/security in a communications system |
| 07/30/1991 | US5036542 Audio surveillance discouragement apparatus and method |
| 07/23/1991 | US5034961 Area communications system |
| 07/17/1991 | EP0436799A2 Communication network with key distribution |
| 06/26/1991 | EP0433782A2 Conference network |
| 06/11/1991 | US5023936 Method and apparatus for externally defining the operational mode of a digital radio transceiver |
| 06/04/1991 | US5022047 Spread spectrum correlator |
| 05/22/1991 | EP0428252A2 A system for controlling access to broadcast transmissions |
| 05/22/1991 | CN1051650A Method and apparatus for encrypting and decrypting time domain signals |
| 05/21/1991 | US5018198 Speech privacy processing method and apparatus therefor |
| 05/16/1991 | WO1991007066A1 Audio surveillance discouragement apparatus and method |
| 05/15/1991 | EP0427600A1 Contact chip card reader |
| 05/08/1991 | EP0425660A1 System and method for communications security protection |
| 05/07/1991 | US5014309 Off-premises cable television channel interdiction method and apparatus |
| 04/24/1991 | EP0424201A1 Decoder for decoding an encrypted television audio signal |
| 04/18/1991 | WO1991005421A1 Method and apparatus for encoding and decoding signals |
| 04/17/1991 | EP0116082B1 Secure coding and decoding system and method for television program signals |
| 04/17/1991 | CN1012410B Communications system with tandem scrambling devices |
| 04/16/1991 | US5008937 Scrambled-communication system using adaptive transversal filters for descrambling received signals |
| 04/04/1991 | WO1991004610A1 Signal digitizing method and system |
| 03/27/1991 | CN1050294A Synchronizing method in mobile radio system |
| 03/26/1991 | US5003591 Functionally modifiable cable television converter system |
| 03/19/1991 | US5001756 Decryption device with variable clock |
| 03/19/1991 | US5001750 Secret communication control apparatus |
| 03/14/1991 | DE4026698A1 Synchronisationsverfahren in einem mobilfunksystem Synchronization method in a mobile communications system |
| 03/13/1991 | WO1991004620A1 Synchronizing method in a mobile radio system |
| 03/13/1991 | EP0416894A2 Method and apparatus for encrypting and decrypting time domain signals |
| 03/06/1991 | EP0414732A1 A method and apparatus for improving video scrambling and employing split sync pulses |
| 03/02/1991 | WO1991003892A1 Improvements in a spread-spectrum multiplexed transmission system |
| 03/02/1991 | CA2064898A1 Spread-spectrum multiplexed transmission system |
| 02/27/1991 | EP0413752A1 In-band controller |
| 02/07/1991 | CA2016009A1 Method and apparatus for externally defining the operational mode of a digital radio transceiver |
| 02/05/1991 | US4991207 One-way address transmission system of PCM music |
| 01/30/1991 | EP0181863B1 Tamper-resistant, expandable communications system |
| 01/29/1991 | US4989245 Controlled authorization of descrambling of scrambled programs broadcast between different jurisdictions |
| 01/15/1991 | US4985919 Secure communication control system |
| 01/08/1991 | US4984219 Method and apparatus for decoding of frequency inversion based scramblers |
| 01/01/1991 | US4982401 Method and apparatus for detecting transmission errors in cordless telephones |
| 12/27/1990 | EP0403570A1 Off-premises cable television channel interdiction method and apparatus. |
| 12/27/1990 | CA1278370C High security pay television system |
| 12/20/1990 | DE3447548C1 Radio transmission method for tactical use - using frequency pumps to transmit information in bursts and returning synthesisers |
| 12/18/1990 | US4979188 Spectrally efficient method for communicating an information signal |
| 12/11/1990 | CA1277764C System for enabling descrambling on a selective- subscription basis in a subscriber communication network |
| 12/11/1990 | CA1277712C Duplex analog scrambler |
| 11/28/1990 | EP0399200A2 Functionally modifiable cable television converter system |
| 11/28/1990 | EP0398931A1 Cryptographic method and apparatus with electronically redefinable algorithm. |
| 11/20/1990 | WO1990014722A1 System and method for communications security protection |
| 11/20/1990 | US4972479 Method and apparatus for providing privacy/security in a communication system |
| 11/20/1990 | US4972473 Data communication method and apparatus using neural-networks |
| 11/20/1990 | US4972469 System and method for communications security protection |
| 11/20/1990 | CA1276682C Secure communication system for multiple remote units |
| 11/09/1990 | WO1990013985A1 An information transmission system |
| 11/09/1990 | CA2055499A1 Information transmission system |
| 11/07/1990 | CN1046826A Ott-premises cable television channel interdiction method and apparatus |
| 10/23/1990 | US4965826 Method of and system for scrambling/descrambling sound |
| 10/23/1990 | US4965825 Method of generating computer output |
| 10/23/1990 | CA1275446C Secure trunked communications system |
| 10/16/1990 | US4964165 Method for the fast synchronization of vocoders coupled to one another by enciphering |
| 10/03/1990 | EP0390056A2 Method and apparatus for descrambling a television signal |
| 09/25/1990 | US4959863 Secret speech equipment |
| 09/12/1990 | EP0386903A1 Controlled authorisation of descrambling of scrambled programs broadcast between different jurisdictions |
| 09/12/1990 | EP0313576A4 Gateway system and method for interconnecting telephone calls with a digital voice protected radio network |
| 09/11/1990 | US4956862 Method of providing sound privacy system compatible with mono and btsc stereo audio |
| 08/28/1990 | US4953211 Encryption apparatus |
| 08/22/1990 | EP0382764A1 Signal processing apparatus and methods. |
| 08/14/1990 | US4949378 Toy helmet for scrambled communications |