Patent ID: 6091562
Filing Date: 2000-07-18
Classification: G11B

Abstract:
A digital magnetic reproducing apparatus comprising a reproducing head to reproduce data from a magnetic recording medium; an equalizer for shaping, by a partial response method, a waveform of the reproduced signal output from said reproducing head; and a decoder for decoding, by a maximum likelihood decoding method, an equalized reproduced signal obtained from said equalizer;said apparatus further comprising:a distortion detector for measuring a second harmonic distortion of the reproduced signal;a decision circuit for making a decision as to whether or not the second harmonic distortion is -25 dB or lower;a measuring circuit for measuring a signal-to-noise ratio of the reproduced signal; anda bias current control circuit supplied with the results of both said decision circuit and said measuring circuit, and controlling the bias current in said reproducing head in such a manner that the signal-to-noise ratio becomes highest in a range where the second harmonic distortion of the reproduced signal is -25 dB or lower.