Patent ID: 7551668

Claim:
An adaptive equalizing apparatus which makes partial response equalization and maximum-likelihood decoding of a read signal from a recording or transmission medium to generate a binary signal, the apparatus comprising: a feedforward nonlinear filter for filtering the read signal; a forward filter controlling means for controlling a tap factor of the feedforward filter; a first maximum-likelihood decoding means for performing maximum-likelihood decoding of the signal filtered by the feedforward filter to generate the binary signal; a second maximum-likelihood decoding means for performing maximum-likelihood decoding of the signal filtered by the feedforward filter to generate the binary signal; a first feedback filter for filtering the binary signal supplied from the first maximum-likelihood decoding means; a second feedback filter for filtering the binary signal supplied from the second maximum-likelihood decoding means; a first feedback filter controlling means for controlling a tap factor of the first feedback filter; a second feedback filter controlling means for controlling a tap factor of the second feedback filter; a first delaying means for delaying the signal filtered by the feedforward filter by a processing time of the first maximum-likelihood decoding means; a second delaying means for delaying the signal filtered by the feedforward filter by a processing time of the second maximum-likelihood decoding means; a first subtracting means for subtracting the signal supplied from the first feedback filter from the signal supplied from the first delaying means; and a second subtracting means for subtracting the signal supplied from the second feedback filter from the signal supplied from the second delaying means, said first feedback filter controlling means controlling the tap factor of the first feedback filter on the basis of the binary signal generated by the first maximum-likelihood decoding means to generate a distortion of a partial response after the leading edge of the binary signal and an ISI (inter-symbol interference) response after the trailing edge, said second feedback filter controlling means controlling the tap factor of the second feedback filter on the basis of the binary signal generated by the second maximum-likelihood decoding means to generate a distortion of a partial response after the leading edge of the binary signal and an ISI (inter-symbol interference) response after the trailing edge, and said feedforward filter controlling means controlling the tap factor of the feedforward filter for the signal supplied from one of the first or second subtracting means to be a partial response.