| 摘要 |
<p>PURPOSE:To prevent the saturation of an envelope detecting output in accordance with the lapse of time. CONSTITUTION:A system is controlled so that plural tracks are reproduced by a head 2 in a certain specified period after the envelope output is obtained first at the time of inserting a tape 1 by a system control means 5, and the maximum value of the detective signal is detected by a peak holding means 6 only in the period when a data updating signal indicating the period is present and the maximum value is analog-digital converted by an A/D converting means and sent to a comparing means 8. Difference data between the maximum value data from the A/D converting means 7 and reference value data indicating the saturation voltage in the circuit is found in the comparing means 8 and sent to a latching means 9. The difference data is updated only when the data updating signal is eliminated in the latching means 9 and converted to the signal corresponding to the difference data by a final control signal generating means 10 and returned to a detecting means 4, and then, the inside gain of the means 4 is changed and the detective signal is formed.</p> |
