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7230941 |
Preamble channel decoding
Rather than attaching a preamble to a data traffic subpacket, a preamble channel is transmitted along with a traffic channel. In a system wherein the data traffic subpackets are variably sized,...
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6965995 |
Signal processing circuit
A signal processing circuit capable of preventing illicit copies, preventing the circuit from being unable to discriminate a plurality of cipher mode and unable to decipher, and correctly decipher...
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6658113 |
Apparatus and method for concealing data bursts in an analog scrambler using audio repetition
An apparatus and method for concealing data bursts in an analog scrambler using parts of the audio of a signal in substitution for the data bursts. What otherwise would be periodic data bursts...
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6460137 |
Encryption processing system
A random-number generator generates first and second title keys on the basis of random numbers. A first DES encryption circuit for the title encrypts input data with the first title key. Initial...
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6424689 |
Radio communication system, transmitter and receiver therefor
In a mobile radio communication system, a transmitter of a base station transmits broadcast information to receivers of mobile stations in the form of frames. The transmitter produces a long frame...
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6240513 |
Network security device
A network security device is connected between a protected client and a network. The network security device negotiates a session key with any other protected client. Then, all communications...
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6151679 |
System and method for preventing a first node from being emulated by another node
A network security device 10 is connected between a protected client 12 and a network 100. The network security device 10 negotiates a session key with any other protected client. Then, all...
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6141533 |
Method and apparatus for a mobile repeater
A mobile repeater (300) is improved to include a database (303) that allows the mobile repeater to store registrations received from subscriber units. Additionally, the mobile repeater may include...
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5974380 |
Multi-channel audio decoder
A subband audio coder employs perfect/non-perfect reconstruction filters, predictive/non-predictive subband encoding, transient analysis, and psycho-acoustic/minimum mean-square-error (mmse) bit...
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5956674 |
Multi-channel predictive subband audio coder using psychoacoustic adaptive bit allocation in frequency, time and over the multiple channels
A subband audio coder employs perfect/non-perfect reconstruction filters, predictive/non-predictive subband encoding, transient analysis, and psycho-acoustic/minimum mean-square-error (mmse) bit...
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5864762 |
Operating a trunked communication system in transmission and message trunked modes
A digitally trunked radio repeater system provides substantial improvements in timeliness and reliability. The mobile radio transceivers transmit channel requests on the control channel at 9600...
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5793869 |
Method and apparatus for encoding and data compressing text information
A method and apparatus for encoding and compressing a text word of ASCII code by substituting a binary number for said word and sending, storing or recording said binary number. The binary number...
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5784422 |
Apparatus and method for accurate synchronization with inbound data packets at relatively low sampling rates
An apparatus and method for accurate synchronization with inbound audio data which packets at relatively low sampling rates. By using previously known information such as the time of arrival of the...
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5757924 |
Network security device which performs MAC address translation without affecting the IP address
A network security device is connected between a protected client and a network. The network security device negotiates a session key with any other protected client. Then, all communications...
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5646606 |
Transmission of transmitter parameters in a digital communication system
In a system for transmitting digital information, transmitter operating parameters (503) are transmitted with other communication message information (501, 505, 507, 509, 511, 513, 515, and 517) to...
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5592556 |
Digital radio with vocoding encrypting codec
A new digital radio includes codec, vocoder and encryption/decryption processing all on a single integrated circuit chip module. Great flexibility is provided in terms of different operating modes...
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5574788 |
Trunked radio repeater system
A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses...
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5563945 |
Data storage device
A data storage device (9) comprises an array of electronic memory locations (20) for storing data. An address input terminal (10) provides coupling to an address source and is coupled to provide...
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5488663 |
Encoding methods for generating a digital signal containing modulated bit allocation information, and record carriers containing that signal
Transmission system for transmitting and receiving, and subband encoding methods for generating for transmission, digital signals containing modulated bit allocation information; and record...
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EP0446194B1 |
Continous cipher synchronization for cellular communication system
Abstract of EP0446194 A system for the synchronization of encryption devices in a digital cellular communications system. Each of the encryption devices includes a multi-bit counter and generates...
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5408680 |
Single channel autonomous digitally trunked RF communications system
A single channel autonomous trunking ("SCAT") RF repeater transmits and receives on a single duplex RF channel. The repeater operates alternately in a control channel mode and in an assigned...
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5375171 |
Transmission system, and transmitter and receiver used in the transmission system for transmitting and receiving digital signals containing modulated bit allocation information
Transmission system, and transmitter and receiver for use in the transmission system for transmitting and receiving digital signals containing modulated bit allocation information. The transmitter...
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5305384 |
Apparatus, system and method for transmitting secure signals over narrow spaced channels
An encryption/decryption device, system and method for providing secure communication over a communication channel. The encryption device includes a radio interface unit connected to a conventional...
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5185796 |
Encryption synchronization combined with encryption key identification
In an encrypted radio system, transmsitters and receivers can each be provided with a plurality of encryption algorithms (407 and 425) and/or encryption key variables (408 and 426). A unique...
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5161193 |
Pipelined cryptography processor and method for its use in communication networks
Cryptographic apparatus, and a related method for its operation, for in-line encryption and decryption of data packets transmitted in a communication network. A full-duplex cryptographic processor...
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5150401 |
Retrofittable encryption/decryption apparatus using modified frequency modulation
A communication system for providing secured communication over a communication channel. The system includes a DES encryption device and a DES decryption device retrofittable into or within a...
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5125102 |
Trunked radio repeater system including synchronization of a control channel and working channels
A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses...
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5070528 |
Generic encryption technique for communication networks
A method and related cryptographic processing apparatus for handling information packets that are to be cryptographically processed prior to transmission onto a communication network, or that are...
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EP0446194A1 |
Continous cipher synchronization for cellular communication system.
A system for the synchronization of encryption devices in a digital cellular communications system. Each of the encryption devices includes a multi-bit counter and generates a pseudo-random...
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5007088 |
Scrambling/descrambling method using a memory for storing initial pseudo-random bit patterns respectively for submultiframes
In a communications system, a multiframe data signal is sent from a transmit end to a receive end of the system. The multiframe is composed of a series of submultiframes each containing a series of...
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4975952 |
Method of data communication
A method of data communication, particularly for long data messages, is disclosed. The data code words of a message are arranged in segments, each with its own header, and are assigned message and...
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4910777 |
Packet switching architecture providing encryption across packets
Apparatus for preventing the unauthorized detection of the start and end of packets being communicated within a packet switching system. The packet switching system comprises a plurality of packet...
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4905302 |
Trunked radio repeater system
A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses...
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4864616 |
Cryptographic labeling of electronically stored data
A method of cryptographically labeling electronically stored data is provided as part of a security system for personal computers. In protecting sensitive files of data, the labeling method...
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