Voice transmission method and apparatus in duplex radio system

摘要

A voice transmission method and apparatus in a duplex radio system are disclosed in which a voice signal to be transmitted in a constant period of time is subjected to 1/N time compression, N being a numeral not smaller than 2.0. The time-compressed voice signal is supplied to a transmitter as a modulating signal and a transmitting operation is performed by the transmitter in synchronism with a period of time when the modulating signal is inputted to the transmitter. A receiving operation of receiving a time-compressed and modulated signal transmitted from the transmitter to demodulate it is performed by a receiver in a period of time other than the period of time when the transmitting operation is performed. A demodulated signal is subjected to N-ple time expansion to obtain a reproduced receive voice signal, and both the transmitting operation and the receiving operation are repeated at the constant period of time. In the voice transmission method and apparatus, a predetermined band of a signal corresponding to said signal to be transmitted, which is in a voice band, is extracted with a predetermined band width. The extracted signal is shifted to any band which is in the voice band and is other than the extracted band. A signal corresponding to the shifted signal is supplied to the transmitter as the modulating signal.