High stability fast tracking adaptive equalizer for use with time varying communication channels

An adaptive equalizer having an input and an output, said equalizer for equalizing a receiver signal input thereto, comprising:

• a plurality of feed forward equalizer (FFE) sections, at least one feed forward equalizer section having tap coefficients and step size parameters that are adjustable separately for each said feed forward equalizer section independent of the tap coefficients and step size parameters of other feed forward equalizer sections, wherein said feed forward equalizer section comprises:
• a linear adaptive digital filter operating on said input of said equalizer delayed in time and generating an output therefrom, said linear adaptive digital filter including a plurality of coefficients;
• an adaptive gain multiplier operating on said output of said linear adaptive digital filter, said adaptive gain multiplier including a gain coefficient;
• a first step size parameter for adapting said plurality of coefficients of said linear adaptive digital filter;
• a second step size parameter for adapting said gain coefficient of said adaptive gain multiplier;
• and
• wherein said first step size parameter and said second step size parameter are set independently for each said FFE section;
• a plurality of decision feedback equalizer (DFE) sections, at least one decision feedback equalizer section having tap coefficients and step size parameters that are adjustable separately for each said decision feedback equalizer section independent of the tap coefficients and step size parameters of other decision feedback equalizer sections;
• a summation unit operatively coupled to the outputs of said plurality of FFE sections and said plurality of DFE sections, said summation unit adapted to add said outputs so as to generate a soft decision output;
• a symbol slicer operatively coupled to the output of said summation unit and adapted to generate estimated symbols yielding a hard decision output;
• an error calculation unit operatively coupled to the output of said summation unit adapted to generate an estimated error signal;
• and
• a controller operatively coupled to said plurality of FFE sections and said plurality of DFE sections, said controller adapted to generate said step size parameters for each FFE section and DFE section in response to sensing variations in the linear distortion of said receiver signal which can be compensated for by said FFE and said DFE sections.