| HITACHI HOME | UP | NEXT | SEARCH | HITACHI

Single-Frequency Duplex Land Mobile Radio

Nobuo Sekiguchi, Hitachi Denshi, Ltd.

ABSTRACT

A new technique for realizing a full duplex radio system using only one frequency is presented.

This system does not require a Press To Talk (PTT) switch. A time division duplex (TDD) method is used by compressing the transmitted voice signal to one-half the original.

By using this technique, a call to the telephone network from a mobile radio via a private branch exchange (PBX) is possible.

Thus, mobile radios using only one frequency are able to communicate with telephone terminals through the network and converse simultaneously.


© Hitachi, Ltd. All rights reserved.