Nondata-aided Timing Recovery for Partial Response CPM

Timing recovery for the binary partial response continuous phase modulation (CPM) is investigated in this paper and a feedforward nondata-aided (NDA) timing algorithm suitable for CPM signals with different modulation indices is proposed. In the algorithm several autocorrelation functions are computed based on the sampled received signal and the lag in the autocorrelation functions is carefully selected depending on the modulation index. And then the timing offset is estimated based on the autocorrelations. Simulation results show that the proposed algorithm works well when the modulation index is at a range of 1/3 to 2/3 and has better performance at higher modulation indices. Additionally, the mean square error of the proposed algorithm can be decreased considerably compared with the existing feedforward NDA timing algorithm.