US 4,308,427 A · Hands-free talk-back intercommunication system

Abstract

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.

Claims13

Dependent claims

A communication system having a talk channel and a listen channel, said system comprising:

a main distribution station;
a plurality of local stations associated with said main distribution station which includes a first local station having a first telephone, and a second local station having a first transducer means in balanced electrical connection with said main distribution station;
means at said main distribution station connected to said first telephone for monitoring when said first telephone initiates a call to said second local station;
means for enabling said monitoring means responsive to a signal from said first telephone;
means for splitting the frequency bands of an address signal from said first telephone;
means for decoding the tones from said split frequency bands;
means for selecting said first transducer means responsive to said monitoring means detecting initiation of a call to said second local station;
means for activating said transducer selecting means responsive to said tone decoding means;
means for supplying electrical power to said transducer selecting means responsive to said tone decoding means;
and
means for controlling said communication of said talk and listen channels between said first telephone and said first transducing means.

8 more elements

A hands-free talk-back intercom system comprising:

a plurality of local stations, at least one of which includes a telephone having a tip and ring circuit and at least a different one of which includes a means for transducing sound pressure waves into electrical signals;
a main distribution station having a first pair of terminals connected to said tip and ring circuit and having a plurality of second pairs of terminals connected to respective pairs of balanced lines which extend to said main distribution station from respective ones of said local stations and to which respective ones of said transducing means are connected at said respective ones of said local stations, said main distribution station further having a listen channel and a talk channel;
means at said main distribution station for generating an oscillating electrical signal in said listen channel;
means for coupling said oscillating electrical signal to said talk channel and to said tip and ring circuit;
means for indicating the relative magnitude of said oscillating electrical signal detected in said talk channel;
and
means for variably adjusting the balance of said coupling means so that said indicating means indicates that a minimum magnitude of said oscillating electrical signal is coupled into said talk channel.

4 more elements

Dependencies are inferred from the claim text.

Hands-free talk-back intercommunication system

Life of this patent

Hands-free talk-back intercommunication system

Life of this patent

Abstract

Claims13