Method for channel tracking in an lms adaptive equalizer for 8vsb

An adaptive equalizer for a digital data receiver, data received by the receiver including coded symbols, the equalizer comprising:

• a tap weight module configured to determine a first set of tap weights and a second set of tap weights of the equalizer;
• a difference module configured to determine a difference between the first and second sets of tap weights;
• an error estimator configured to determine an error estimate based on symbols received at the receiver;
• a comparison module configured to compare the error estimate with a divergence threshold;
• and
• a step size factor module configured to determine a step size factor based on the difference and the comparison.

A device configured to process digital television signals, the device comprising:

• a receiver including a demodulator, a decoder, and an equalizer,
• the receiver configured to receive radio frequency signals modulated with data including coded symbols and uncoded symbols,
• the demodulator configured to demodulate the received radio frequency signals to produce the coded symbols and the uncoded symbols,
• the decoder configured to decode the coded symbols to produce corresponding decoded symbols, and
• the equalizer including
• a tap weight module configured to determine a first set of tap weights and a second set of tap weights of the equalizer,
• a difference module configured to determine a difference between the first and second sets of tap weights,
• an error estimator configured to determine an error estimate based on symbols received at the receiver,
• a comparison module configured to compare the error estimate with a divergence threshold, and
• a step size factor module configured to determine a step size factor based on the difference and the comparison.

A method of determining a step size for a linear-mean-squared (LMS) equalizer of 8-level-vestigial-sideband (8VSB) modulated signals having trellis-coded symbols and segment sync symbols, the method comprising:

• (a) determining a mean-squared-error estimate based on at least one of decoded trellis-coded symbols and the segment sync symbols;
• (b) determining a first set of tap weights and a second set of tap weights of the equalizer;
• (c) determining a 2-norm of the difference between the first and second set of tap weights;
• (d) comparing the error estimate with a divergence threshold;
• (e) if the error estimate is less than the divergence threshold, comparing the 2-norm with a plurality of difference ranges including a first difference range, each of the difference ranges having a corresponding step size increment, selecting the corresponding step size increment of the first difference range if the 2-norm is within the first difference range, and incrementing a base step size based on the step size increment to determine a step size, and determining a third set of tap weights based on the step size;
• and
• (f) iteratively performing acts (a-e).

A digital communication receiver configured to receive radio frequency signals modulated with data including coded symbols and a priori known uncoded symbols, the receiver comprising:

• a demodulator configured to demodulate the received radio frequency signals to produce the coded symbols and the a priori known uncoded symbols;
• a decoder configured to decode the coded symbols to produce corresponding decoded symbols;
• and
• a frequency domain equalizer including
• a difference module configured to determine a difference between a first tap weight vector and a second tap weight vector,
• an error estimator configured to determine an error estimate based on the decoded symbols or the uncoded symbols,
• a comparison module configured to compare the error estimate with a divergence threshold, and
• a forgetting factor module configured to determine a forgetting factor based on the difference and the comparison.