Method and apparatus for mixing low-frequency signals transmitted via different time slots towards the same telephone receiver set

摘要

A plurality of PCM signal samples destined for the same telephone set are transmitted over different respective time slots of a time divided transmission link serving the telephone set. Each sample destined for the telephone set is decoded during a single time slot, the resulting decoded pulses are added together once per frame, and the sum transmitted to the telephone set for a period which is equal to the duration of one frame. The summing unit is coupled firstly to the output of a digital-to-analog converter and secondly to the input of a hold circuit. Its main components are an operational amplifier and capacitors which are suitably connected by transistors.