Abstract: A synchronizing circuit for use in time division simultaneous telecommunication for attaining synchronized alternate transmission and reception of aural signal between a calling station and a called station at a predetermined rate of time division.

Abstract: A radio communication system for simultaneous telecommunication between a calling station and a called station using a carrier of single frequency for carrying audio information, in which a time division pulse signal within the audio frequency range is generated for synchronous transmission and reception of the audio signals in these stations in time division fashion. The audio signals received at a station during one pulse interval are delayed and combined with the signal portion received during the one pulse interval to provide a composite signal comprised of the same audio signal in two successive pulse intervals. Voice control means are also provided so that the radio communication system can make continuous signal transmission and reception in time division fashion when audio information to be transmitted is applied to the microphone, and the system can be placed in the receiving mode when such input is not applied to the microphone.

Abstract: A radio communication system for simultaneous telecommunication between a calling station and a called station, in which an aural signal to be transmitted from the calling station is divided by sampling pulses in the form of clock pulses of low frequency and is then suitably compressed with respect to the time axis to produce periodic signal-free time regions in the compressor output, so that an aural signal similarly compressed with respect to the time axis and transmitted from the called station can be received within these signal-free time regions. The received aural signal is expanded with respect to the time axis so that the original aural signal output of the microphone in the called station can be reproduced and applied to the speaker in the calling station. A zero cross synchronizing circuit is connected to the compressor to attain zero cross synchronization of the time-divided compressed aural signal and such aural signal is applied to the transmitter.