DATA TIMING RECOVERY FROM DISTORTED MULTI-LEVEL CODED SIGNALS

摘要

In a data modem using adaptive equalizers, a data symbol timing recovery arrangement generates timing signals in a threshold crossing path (TCTRL) during a training phase of pseudo-random data in binary rather than multi-level form. An adjustable-phase shifter (APS) is set during the training period so that the Nyquist-derived signal is in phase with the threshold-derived signal. During multi-level transmission, the Nyquist-derived signal is employed for timing purposes having been phase-corrected in the shifter(APS), which maintains the same phase shift until the next training period.