Improvements in or relating to telecommunication systems

摘要

In a method and apparatus for reducing the bit rate of transmitted signals in a telecommunications system, a speech recognition device is operated in parallel with a speech coding device in a transmitter terminal. An analog input signal from a microphone is digitized in an analog-to-digital converter to provide a digital signal which is applied to both the speech coding device and the speech recognition device. An output signal for transmission via an antenna is formed by combining output signals from the speech coding device and the speech recognition device via a switch, recognized speech being converted to codewords which replace packets or sequences of packets of the coded signal corresponding thereto. In a receiver terminal, an antenna receives the transmitted signal and passes it to both a speech coding device and a speech generator prior to being converted to an analog signal for a speaker. The speech generator recognizes codewords present in the signal, converts them back to digital signals and then overwrites a digital signal from speech coding device via switch to reconstruct the complete signal prior to being passed to digital-to-analog converter.