Patent ID: 7193802

Claim:
A read channel, comprising: an equalizer configured to equalize a digital signal to provide equalized reproduced signals; and a Viterbi detector capable of receiving the equalized reproduced signals and converting the reproduced signals into a digital output signal indicative of data stored on a recording medium; wherein the equalizer is implemented using a coefficient learning circuit that adaptively updates coefficients for the equalizer based upon a cosine function, the coefficient learning circuit adjusting coefficients using a tap coefficient update equation having a first parameter, k, for modifying a magnitude response, wherein the first parameter, k, is adjusted according to k=k−g*(f(a k+1 )+f(a k−1 ))*e k , wherein k is the cosine equalizer parameter for modifying the magnitude response, g is an update attenuation gain, f( ) is a predetermined cosine function, a k+1 represents a bit to be detected at time k+1, a k−1 represents a bit to be detected at time k−1, and e k is an error signal based on a difference between a noisy equalized signal and a desired noiseless signal.