Half-duplex communications system - allows listener to interrupt speaker by disconnecting his transmit amplifier and connecting in his receive amplifier

摘要

The half-duplex communications system allows the listener to interrupt the speaker even when the latter's speak button is depressed. The main station transmits an AF signal that operates the control relay for half-duplex transmission circuit and the half-duplex receive circuit in the outstation (N) using the contacts (b5) of the standby relay (B). The transmit amplifier (SN) in the outstation is thereby switched out by the main station and its receive amplifier switched in. The coupler in the main station is bridged by an attenuator.