Abstract: An electronic unit operable in conjunction with a body unit and used by mounting it on an automotive vehicle. The electronic unit includes first and second connectors which produces a coupled-status signal when the electronic unit is coupled to the body unit and a decoupled-status signal when the electronic unit is decoupled from the body unit. A microcomputer is coupled to the first connector and is selectively placed to a start mode when the coupled-status signal is received from the first connector and to a stop mode when the decoupled-status signal is received therefrom. The microcomputer produces clock pulses when it is in the start mode and a stop signal when it is in the stop mode. A timer is coupled to the microcomputer and outputs a reset signal to the microcomputer when the clock pulses are not received for more than a predetermined period of time. The timer further inhibits the reset signal from being outputted when the stop signal is received.

Abstract: A communications system for identifying a responding station called by a communications system caller station over a call channel and a plurality of speech channels. The system transmits information from the caller station, such as the selected speech channel and the designated responding station through the call channel, and receives information from a responding station on the selected speech channel. The communication between the communications system and the responding station on the selected speech channel is enabled only when information from the responding station is identical to information of the designated responding station transmitted from the communications system.