Adaptive equalizer having a variable step size influenced by output from a trellis decoder

An adaptive equalizer comprising:

• a decision device;
• an FIR filter coupled to the decision device;
• a DFE coupled to the decision device, the DFE producing a DFE output;
• a Viterbi decoder coupled to the decision device, the Viterbi decoder producing a reliability output and a decoded output;
• a mapper coupled to receive the decoded output of the Viterbi decoder and to generate a mapped and scaled output;
• wherein the error signal is generated by delaying the DFE output by a number of cycles equal to a number of cycles the Viterbi decoder uses to generate the reliability output and subtracting the delayed decoded output of the DFE from the mapped and sealed output of the mapper;
• wherein a magnitude of change in the coefficient of the adaptive equalizer is selected based at least in part upon the reliability output and at least in part upon the error signal.