Some methods of error signal detection in PAM-systems for multiplex transmission of synchro data

It is often desirable to transmit synchro data over a two-wire line or radio link. This can be done by using time division multiplex. The amplitudes are then sampled and transmitted as pulse trains representing the sine and cosine of the shaft angles of the synchro transmitters. This paper discusses various methods of producing the servo error signals from the information in the received pulse trains.