The design of a multi‐speed PSK modem
Jeffrey Lin, Hen‐Wai Tsao, Jin‐Fu Chang · Journal of the Chinese Institute of Engineers · 1985
This paper discusses how to use the polarity distribution characteristics of echo modulation to design a multi‐speed PSK modem. This modem includes the following special features: (1) three modulation methods (BPSK, QPSK, 8PSK) at three different data speeds, (2) unique initial synchronization algorithm, (3) differential encoding and other software techniques to reduce the bit error rate and to eliminate incorrect timing adjustment when patterns with mismatched polarity are received.