| 摘要 |
PURPOSE:To prevent the breakdown of a data file by deciding the deterioration of a magnetic recording medium in case a frequency component having the voltage higher than fixed level is detected. CONSTITUTION:The voltage signal delivered from an amplifier 3 is supplied to an envelope signal extracting circuit 6. Then only the envelope signal is extracted and sent to a band pass filter 7, and the envelope signal value obtained by the minute waves on the surface of a magnetic recording film is extracted. Then a deciding circuit 8 decides whether the output voltage of the band pass filter 7 of the envelope signal is higher than a prescribed level or not. If said output voltage is higher than a prescribed level, the deterioration of a magnetic recording medium is decided. The voltage signal delivered from the amplifier 3 can be recovered up to a proper level of voltage by an automatic gain controller 4. Then the breakdown of a data file can be avoided by transcribing the data on a deteriorated track to another normal track or transcribing all data files to a new medium.
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