A new symbol timing tracking algorithm for pi /2-BPSK and pi /4-QPSK modulations

Abstract

A timing tracking synchronizer structure for pi /2-BPSK (binary phase shift keying) and pi /4-QPSK (quadrature PSK) is presented and evaluated for various channel conditions. The timing tracking synchronizer is based on the nonlinear spectral line method where the received signal is passed through a nonlinearity to generate discrete spectral components related to the symbol rate. The synchronizer then makes judicious use of this timing information. The authors discuss the principle of operation and point out the practical aspects of its implementation. Estimates of the timing jitter variance are obtained through simulation for several channel conditions typical of mobile-satellite communications. It is shown that the performance is insensitive to the amplitude nonlinearity of the transmitter amplifier. Results show also that the timing synchronizer can make efficient use of the multipath energy in a flat-fading channel.<>