Patent ID: 7050491

Claim:
A method for adapting adjustable weighting coefficients of a feed-forward finite-impulse-response (FIR) digital filter that provides for performing at least a part of the channel-equalization and echo-suppression filtering of successive samples of a demodulation signal resulting from demodulation of an amplitude-modulation signal descriptive of digital symbols occurring at a baud rate, which demodulation signal is subject to being accompanied by unwanted echoes because of said amplitude-modulation signal being received via a channel that at times has more than one length of propagation path therethrough, which unwanted echoes are to be suppressed in successive baud-rate samples of a baseband response of said channel-equalization and echo-suppression filtering to said successive samples of said demodulation signal, said method comprising steps of: initially measuring the echo content of samples of said demodulation signal to determine an initial channel impulse response (CIR) that characterizes the reception channel in the time-domain; measuring reception error in said baseband response of said channel-equalization and echo-suppression filtering to said successive samples of said demodulation signal; continuously updating the CIR responsive to said reception error; periodically, normalizing the CIR with respect to the strength of a cursor component thereof to generate a normalized CIR; convolving the normalized CIR with at least a portion thereof to generate a synthetic normalized CIR; and determining the weighting coefficients of said feed-forward FIR digital filter from corresponding terms of said synthetic normalized CIR.