Communications with adaptive equalization

An apparatus comprising:

• an equalizer circuit configured and arranged to modify a frequency component of received signals based on an error signal;
• a sign circuit configured and arranged to replace sign bits having a value of “1” in the received signals with a sign bits having a value of “0”;
• a slicer circuit connected to receive the signals having a sign bit assigned by the sign circuit, and configured and arranged to slice the received signals;
• a sign-bit detection circuit configured and arranged to detect a sign bit of a signal output by the equalizer circuit and to assign a sign bit to the output of the slicer circuit based upon the detected sign bit;
• and
• a summation circuit configured and arranged to sum the output of the equalizer with the output of the slicer circuit having the sign bit assigned thereto, and to provide the sum to the equalizer as the error signal.

A method comprising, for each of a plurality of signals received on a communication channel and presented to an equalizer:

• assigning a sign to the signal by generating an output signal that is an absolute value of the received signal;
• processing the generated signal to provide a level-limited signal having a voltage level limited to a predetermined value;
• detecting a sign of a signal output by the equalizer and assigning a sign to the level-limited signal based upon the detected sign;
• summing the output of the equalizer with the level-limited signal having the sign assigned thereto, and providing the sum as an error signal;
• and
• in the equalizer, using the error signal to modify a frequency component of a received signal.