Patent ID: 6697423
Filing Date: 2004-02-24
Classification: H04L

Abstract:
A decision feedback equalizer for determining a data value in a received signal sample s(t) in the presence of intersymbol interference (ISI) comprising:a DFE block for generating a signal s1(t) which is an estimate of all except a most recent post-cursor ISI term and for generating coefficients aâˆ’1, a0 and a1; a first subtractor for subtracting said signal s1(t) from said received signal sample s(t) and in response generating an error sample e1(t); a second subtractor for subtracting said most recent post-cursor ISI term from said error sample e1(t) and in response generating a further error sample e2(t); a main decision block for receiving said further error sample e2(t) and in response generating a current data value estimation and an ambiguity indicator mt in said current data value; and a secondary decision block for receiving said error sample e1(t), receiving and delaying said current data value estimation and ambiguity indicator mt thereby resulting in a previous data value estimation and previous ambiguity indicator mtâˆ’1, respectively, and in response generating an adaptive decision threshold (Ctâˆ’1) based on said previous data value estimation and (i) in the event said previous ambiguity indicator mtâˆ’1 indicates no ambiguity then outputting said previous data value estimation and (ii) in the event said previous ambiguity indicator mtâˆ’1 indicates ambiguity then modifying said previous data value estimation based on a comparison between said error sample e1(t) and said adaptive decision threshold Ctâˆ’1; and an ISI calculation block for receiving said current data value estimation, said previous data value estimation, said coefficients aâˆ’1 and a0, and a delayed version of said further error sample e2(t), and in response generating a final error signal e(tâˆ’T) in which signal contributions from said current data value estimation, said post-cursor ISI and a most recent precursor ISI term have been subtracted, for adapting said coefficients.