DIGITAL VSB DETECTOR WITH BANDPASS PHASE TRACKER, AS FOR INCLUSION IN AN HDTV RECEIVER

摘要

In a radio receiver for receiving vestigial sideband (VSB) signals including symbol codes descriptive of digital signals, HDTV signals being exemplary of such VSB signals, a tuner provides for selecting one of channels at different locations in a frequency band used for transmitting such VSB signals. The tuner also includes mixers for performing plural conversion of the selected channel to a final intermediate-frequency signal, which is digitized by an analog-to-digital converter. A phase tracker, operative on narrow-bandpass filtered portions of the digitized final intermediate-frequency signal centering on its carrier frequency, suppresses an imaginary portion of the final intermediate-frequency signal, arising from multipath distortion or from phase incoherency in local oscillations used during frequency conversion. A digital controlled oscillator in the phase tracker supplies digital descriptions of the carrier wave for the final intermediate-frequency signal to a synchronous detector, which synchronous detector detects the real portion of the digitized final intermediate-frequency signal in accordance with those digital descriptions of the carrier wave.