Three-port conference circuit for use in a digital telephone system

摘要

A three-port conference circuit for use in a pulse code modulated communication system including a first speaker register including an input connected to a telephone system information memory output and including an output, a second speaker register including an input connected to the telephone system information memory output and including an output and a conference adder connected to the first and second speaker register outputs via inputs and including an output connected to a sample inverting circuit of the telephone system. The conference adder adds talking samples by means of an included eight-bit floating point adder.