PLL synchronization for coded modulation

Joint maximum-likelihood estimation of data and reference phase is a preferred method of reception/phase synchronization for trellis-coded modulations. Often, this joint estimation process is too complex. To avert this problem several researchers have proposed methods that decouple data and phase estimation. In such schemes, tentative data estimates are required by the synchronizer, and to improve these estimates, their release to the synchronizer is delayed. However, this delay also slows the synchronizer´s response to rapid phase reference changes. The effect of this delay is explored. Also presented is an improved synchronizer that, although it operates without delay, suffers from few of the effects associated with poor data estimates