US 4,907,100 AGranted

Readout circuit in magnetic recording device

AssigneeHitachi, Ltd.

InventorsNobumasa Nishiyama, Makoto Saito, Yasuhide Ouchi, Yasuhiro Katoh, Yoshihasa Kamo, Makoto Koizumi, Hajime Aoi, Naoki Sato, Reijiro Tsuchiya

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Abstract

A readout circuit in magnetic recording device is disclosed, in which a test data signal for detecting an error in the characteristics of an automatic equalizer is recorded in a predetermined position of each track of a magnetic recording medium. In readout mode, a test data signal for a selected track is read out first, and this signal is compared with a reference signal dependent on the system conditions to determine an error from the reference signal. The optimum equalization coefficient is determined to eliminate this error from the reference signal and is set in the equalizer. The data is readout under the optimum equalization characteristics thus set.

Claims13

Dependent claims

A readout circuit in magnetic recording device comprising:

a magnetic head for reading a read out signal from a recording medium on which there are recorded at least one of test data having positive and negative amplitudes which are determinable prior to reading data recorded on said recording medium, and test data resulting in a read out signal which becomes an isolated waveform,
an equalizer for shaping said read out signal,
means for detecting a difference between the absolute values of amplitudes of two portions of a waveform included in said read out signal shaped by said equalizer, and the distance between specified level points which are not zero in the waveform included in said read out signal,
means for comparing a difference between the absolute values of the amplitudes of the two portions of the waveform detected by said detection means and a reference value, and said distance between said specified level points in the waveform and said reference value,
means for operating said detection means and said comparing means during at least a period when said magnetic head reads out the test data,
controller means for controlling said equalizer so that the difference between the absolute values of the amplitudes of two portions of the waveform detected by said detection means and the distance between the specified level points in the waveform are substantially consistent with said reference value,
a pulse generator for forming a peak pulse from said read out signal shaped by said equalizer, and
a data detection unit for forming data from the peak pulse formed by said pulse generator.

5 more elements

A readout circuit in a magnetic recording device comprising;

a magnetic head for reading a read out signal from a recording medium on which there are recorded test data having positive and negative amplitudes which are determinable prior to reading data recorded on said recording medium;
an equalizer for shaping said read out signal;
means for detecting a difference between the absolute values of amplitudes of two adjacent positive and negative portions of a waveform included in said read out signal shaped by said equalizer, and the distance between peak level points in the waveform;
means for comparing a difference between the absolute values of the amplitudes of two positive and negative portions of the waveform detected by said detection means and a reference value, and the distance between peak level points in the waveform and said reference value;
means for operating said detection means and said comparating means during at least a period when said magnetic head reads out the test data;
controller means for controlling said equalizer so that the difference between the absolute values of the amplitudes of the two positive and negative portions of the waveform detected by said detection means and the distance between the peak level points in the waveform are substantially consistent with said reference value;
a pulse generator for forming a peak pulse from said read out signal shaped by said equalizer;
and
a data detection unit for forming data from the peak pulse formed by said pulse generator.

6 more elements

Dependencies are inferred from the claim text.