Timing and Doppler recovery for frequency hopped systems

In this paper we propose an algorithm for timing and Doppler recovery for coherent M-ary Phase Shift Keying (MPSK) receivers for frequency hopped systems. The algorithm is based on data aided (DA) approach. It consists of a pull-in algorithm for timing recovery followed by a Doppler canceller. The pull-in algorithm is based on a set of six correlators spaced equally by a half symbol period (T_sym) and an interpolation filter. This technique approximates the maximum likelihood (ML) technique. It reduces the software/hardware computational resources significantly. The interpolation filter is designed to exploit the property of the transmitting filter. It is chosen to satisfy the Nyquist zero-intersymbol interference (ISI) criterion. The Doppler cancellation algorithm is based on the decision directed least mean square (LMS) approach. Computer Monte Carlo simulation is used to evaluate the performance of the recovery algorithm.