| 摘要 |
<p>PURPOSE:To stably and surely reproduce a signal at double speed by comparing reproduced envelope levels in plural prescribed positions of a recording track and using the level difference as tracking information. CONSTITUTION:A reproduced signal (a) has the envelope detected by an envelope detecting circuit 11 and is supplied to a sample-and-hold circuit 12 and the inverted input terminal of a level comparator 13. A signal (c+) which has the level held by a sampling pulse (i) is outputted from the sample-and-hold circuit 12 to the non-inverted input terminal of a level comparator 13. Subtraction is performed in the level comparator 13, and the output is supplied to a sample-and-hold circuit 14. A square wave (e) is generated since a sampling pulse (k) is supplied to the sample-and-hold circuit 14 from a sampling pulse generating circuit 19, and this square wave (e) is supplied to a capstan motor driving control circuit of the following stage as the tracking control signal.</p> |
