Abstract: A digital system utilizing communication satellite links is arranged to minimize the satellite link transmission time delay variation and achieve bit synchronization of the incoming data to a common bit clock at a central tandem switching or collection center.The incoming data bit rate from each subsidiary center is monitored by suitable means such as a threshold detector to determine if the time delay rate is changing relative to the tandem center central timing. Each of the lines from every subsidiary center has minimal buffering means in the tandem center to absorb short-term changes in the input data rate. A message selecting and encoding network is provided in the tandem center for each subsidiary center to generate a return bit rate message to its respective subsidiary center. Each subsidiary center is provided with suitable decoders, logic, and an oscillator to change the data bit rate in response to the control message from the tandem center.