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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.