Clock compensation in a data/fax relay system

In Data/Fax relay applications, one challenge is to overcome problems associated with having independent clocks in the system. Due to slight differences in the clock frequency of the relay system compared to the far modems (fax machines), the relay system is unable to transmit with the same rate that it receives data. Eventually, the system either starves for data or loses data due to under/over flow of its buffers. The clock difference problem in a Demod/Remod system and a method to compensate for it is addressed in this paper. The transmitter clock in each side of the relay system is tuned to match with the clock rate at the other side. This clock tuning is done via a closed loop feedback system. The bit error rate measurements show a significant improvement in the performance of the Demod/Remod system when the clock difference is compensated.