Improved feedforward ML timing estimation for PSK signaling

A non-data-aided (NDA) feedforward symbol synchronizer for M-ary phase-shift keying (M-PSK) signals based upon the maximum-likelihood (ML) criterion is proposed. The algorithm is well suited for burst-mode, narrow-band communication systems, offering significant improvement over other popular synchronizers. Although knowledge of the carrier phase is required (coherent synchronizer) the low variance of the estimates produced by this algorithm make it attractive in applications where the carrier phase is known. The proposed synchronizer is compared to another recently derived, carrier phase independent algorithm. The performance of both synchronizers is assessed by simulation using QPSK signaling and compared to that of other well-known and popular circuits such as the square-law synchronizer