Patent ID: 7009793

Claim:
A magnetic disk apparatus including: a read gate generation unit which generates a read gate signal having a predefined read start time and read end time that are set using a sector pulse as a reference; and a data demodulation unit which reproduces read data from a medium readout signal by executing a read based on the read gate signal, the magnetic disk apparatus comprising: a read gate optimization unit which detects errors of read data demodulated by the data demodulation unit while varying the read start time and the read end time of the read gate signal, the read gate optimization unit determining the read start time and the read end time at which the detected errors are minimized and setting the determined read start and end times in the read gate generation unit; and wherein the read gate optimization unit includes: a timing adjustment unit which varies the read start time and the read end time of the read gate signal for output to the data demodulation unit, for each of plural times of executions of test read; an error detection unit which detects errors of the read data demodulated by the data demodulation unit, for each execution of test read, based on the read gate signal output from the timing adjustment unit; and an optimum time determination unit which determines as optimum times the read start time and the read end time of the read gate signal at which the errors are minimized of a plurality of errors detected by the error detection unit, the optimum time determination unit setting the determined optimum times in the read gate generation unit.