| 摘要 |
PROBLEM TO BE SOLVED: To provide a disk device and method realizing the reduction of the time for optimizing a signal channel parameter, by which the performance of the disk device is improved. SOLUTION: In the measurement of an error rate performed in the process to optimize the signal channel parameter of the disk device, the error rate is deteriorated by means of deteriorating the S/N ratio of an input signal, thereby the decision of the optimized parameter value is attained by the error rate test of less transfer bits. An attenuator 3 is connected between the output of an R/W IC 2 and the input of an AGC circuit 4, and the attenuation amount of the input signal is controlled by a disk controller 9 while monitoring the measurement result of the bit error rate, and the signal channel parameter is efficiently optimized by adequately deteriorating the S/N ratio of the input signal, then the reduction of the test time is realized.
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