| 摘要 |
<p>PURPOSE:To always perform precise speed discrimination and tracking control by correcting the deviation between the center values of a level comparator and an A/D converter. CONSTITUTION:Pilot signals which are reproduced by a head 13 are multiplied by reference pilot signals at a balanced modulator 3 and difference signals between 3fH and fH are inputted to a level comparator 8 and compared. AFT error signals, which are the compared results, are converted into digital signals by an A/D converter 91 of a microcomputer 9 and inputted into a center correction and inverse processing section 92. The section 92 performs inverting and noninverting operations of the inputted digital signals in synchronization with head switching pulses. During these operations, the fluctuations caused by the deviations are eliminated from the ATF error signals that are inputted to a tracking control section 93 and a speed discrimination section 94 so as to compensate for the deviation of center values of the comparator 8 and the converter 91.</p> |
