Tracking performance analysis of feedback timing synchronizers operating on interpolated signals

This contribution deals with the tracking performance of a timing recovery loop, operating on a sampled cyclostationary signal. In the case of synchronized sampling, timing correction is performed by adjusting the phase of the sampling clock according to the timing error detector output. In the case of non-synchronized sampling, timing correction is performed by interpolating between the available samples taken by a fixed free-running clock; the interpolator control is derived from the timing error detector output. Our tracking performance analysis shows that the timing error resulting from the synchronizer operating on the interpolated signal contains periodic components, whose frequencies are related to the (possibly irrational) number of samples of the fixed clock per period of the cyclostationary signal. The presence of these periodic components is confirmed by computer simulation. The periodic components are caused solely by non-ideal interpolation, which implies that they do not occur when using synchronized sampling