Hands-free talk-back intercommunication system

摘要

A hands-free talk-back two-way intercommunication system is disclosed. The system includes a plurality of local stations connected to a main distribution station. Also connected to the main distribution station may be a direct station selector. At least one of the local stations includes a telephone and at least one of the other local stations includes a transducer element. The telephone and the transducer element may be connected in communication with each other through the main distribution station which includes a listen/talk channel controlling member, a call monitoring member and a station selecting member. The listen/talk channel controlling member includes apparatus for adjusting the balance between the listen and talk channels. The channel controlling member also includes apparatus for providing a notification signal to any transducer member which is addressed by the telephone. The channel controlling member further includes apparatus whereby either one of two levels of gain can be used in providing a conversational signal between the telephone and accessed transducer element.