Cross-connection network using time switch

Abstract

An internal frame signal producing circuit for use in a cross connection system which cross connects first bit rate signals, each produced by multiplexing m second bit rate signals at first or the second bit rate signal levels, the first bit rate being higher than the second bit rate, an internal frame frequency is predetermined to be equal to a frequency f.sub.h ' higher than a first nominal frequency f.sub.h of the first bit rate digital signals by a predetermined value, the frequency f.sub.h ' being synchronized with a second nominal frequency fl of the second bit rate digital signals. In order to obtain the internal frame signal, from m second bit rate signals, the m second bit rate signals are stuff-synchronized processed to produce m stuff-synchronized signals, each having a stuff bit, a variable bit, and vacant bit at suitable bit intervals in a frame of a frame length. The m stuffed-synchronized signals are serially arranged to make the internal frame signal. In order to compensate a frequency difference between f.sub.h ' and fl, one frame consisting of all vacant bits is assigned at predetermined frame intervals.