Subscriber's circuit for time division switching system

Abstract

A click tone removing system for a time division switching system which performs switching of speech channels by a highway switch inserted in a highway. When a hook information detector and a dial information detector detect hook information and a dial information, respectively, delivery of a PCM speech sending signal to the highway is prevented by a blocking function for a fixed period of time, so that the highway is controlled to switch the speech channel, thereby removing a click tone generated by dialing. A subscriber's circuit of an exchange, which changes over a speech sending highway and a speech receiving highway by means of a highway switch, is characterized by the provision of an A/D converter for digitizing a speech sending signal to a digitized speech sending signal sent out to the speech sending highway, a D/A converter for converting a digitized speech receiving signal applied from the speech receiving highway into an analog signal, a gate for gating the input signal to the D/A converter, and a control circuit for controlling the gate, so that during real time processing the speech receiving signal highway is interrupted by opening and closing the gate without controling the higway switch.