A Method of UQPSK-DSSS Timing Synchronization for Non Integer Sampling Rate

Abstract

This paper presents a method of UQPSK-DSSS timing synchronization. There exists a problem that non integer oversampling of signal can cause big jitter in both transmitter and receiver. In transmitter, this research reduces jitter by replacing the traditional digital interpolation with a new module which includes interpolation, shaping filtering and decimation. Moreover, in receiver, timing offset estimation module and symbol interpolation module are added. The previous module estimates the normalized timing error value in the non-spread spectrum branch and then the latter module uses the symbolic interpolation operation to realize accurate timing synchronization in the situation of low oversampling rate. In this way, the stability of locked loop in receiver can be guaranteed. We also verify the feasibility and the performance of this method by simulating on MATLAB. An advantage of this method is that joint demodulation of TT&C link and data transmission link can be realized only utilizing the stable cumulant of NCO phase of delay locked loop based on the characteristics of precisely aligned coupling of UQPSK-DSSS signal.