Hitachi Denshi Kabushiki Kaisha

Fuji-tekku Kabushiki Kaisha

Tohoki Electric Power Co., Inc.

Kiyoyuki Isawa

Kenichi Suzuki

Sakari Ohira

Fujio Sumi

Kazuo Suzuka

Nobuo Sekiguchi

Takashi Kurokawa

Katsumi Takahashi

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.

Voice transmission method and apparatus in duplex radio system

Growing community of inventors

Kawasaki, Japan

Kiyoyuki Isawa