Decision feedback equalizer and transceiver

A method for adapting an equalizer having a plurality of taps spaced sequentially at periods of one clock unit for observing a digital data system response produced by a digital system, comprising:

• applying an arbitrary digital data sequence to the digital system;
• detecting a first predetermined digital data pattern in the data sequence;
• calculating a first error signal for a first tap of the plurality of taps based on the system response to the first data pattern;
• using the first error signal to adapt the first tap;
• and
• repeating the steps of detecting, calculating, and adapting for each tap other than the first tap in the plurality of taps,
• wherein:
• the digital data pattern used in conjunction with a given tap at position k in the plurality of taps has equal symbol values at positions (m−k) and (m−k−1) and different symbol values at positions (m−p) and (m−p−1), where p is not equal to k, for some value of m, thereby comprising a digital data pattern having a lone bit;
• and
• the error signal calculated for the tap at sequential position k is proportional to the sum of the values of the system response measured at zero crossings directly before and after the lone bit of the digital data pattern.