Matches 1 - 9 out of 9
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7319756 Audio coding  
Coding of an audio signal (x) is provided where the coded bitstream (AS) comprises a parametric representation of the audio signal. One component of the parametric representation comprises tracks...
6266418 Encryption and authentication methods and apparatus for securing telephone communications  
An encryption device for a telephone having a handset and a base unit is disclosed. The device includes a handset interface, a first converter, an encryption processor, a second converter, and a...
5781882 Very low bit rate voice messaging system using asymmetric voice compression processing  
An apparatus and method for processing a voice message to provide low bit rate speech transmission processes the voice message to generate speech parameters which are arranged into a two...
5761632 Vector quantinizer with distance measure calculated by using correlations  
A vector quantizer for a speech coder for coding speech signals at low bit rates. The vector quantizer includes an auto-correlation calculation circuit for calculating an impulse response of a...
5701294 System and method for flexible coding, modulation, and time slot allocation in a radio telecommunications network  
A system and method for dynamically adapting the user bit rate of a time division multiple access (TDMA) cellular telecommunication system to achieve optimum voice quality over a broad range of...
5323463 Method and apparatus for controlling the spectral content of a data stream  
An FDDI transmitting apparatus employs a scrambler to scramble input NRZ data which in turn is input to an NRZI-to-NRZ pre-encoder. This is in turn coupled in series with an NRZ-to-NRZI encoder to...
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...
4893339 Secure communication system  
Disclosed is a synchronous secure communication system wherein an information signal is encrypted in an encryption means. The encrypted signal is compressed to allow the insertion of a...
4817141 Confidential communication system  
The respective feature parameters extracted from a speech signal is converted into the corresponding line spectrum data in a first frequency band obtained by dividing the speech signal frequency...
Matches 1 - 9 out of 9