Digital Phase Detector for Nyquist and Faster than Nyquist Systems

The quality of clock tone in many practical phase detectors depends on the width of the non-zero portion of the signal spectrum. In Nyquist systems that deploy the raised-cosine filter, most of the known timing extraction methods completely fail when the roll-off factor (ROF) approaches the zero value. In this letter, we present a novel digital phase detector that is based on two samples per symbol with a performance that is practically independent of the shape of the Nyquist filter and modulation formats. Excellent timing-error detector performance is demonstrated even in extremely band-limited systems - the so-called faster than Nyquist systems (FTN).