A system for detecting errors in a channel includes a signal detector to detect a first sequence from the channel, the first sequence comprising a plurality of symbols. A decoder determines a total number of symbols in error in the first sequence. A decoder asserts a failure indication when the total number of symbols in error in the first sequence is greater than a predetermined threshold. A controller causes the signal detector to detect a second sequence from the channel in response to the decoder asserting the failure indication. The decoder identifies corresponding symbols in the first sequence and the second detected sequence that differ.