| 摘要 |
PURPOSE:To control the resonance frequency, Q, recording level, etc. in a short time by detecting the level of the reproduction signal converted into a digital signal with the prescribed sampling timing. CONSTITUTION:The video signal reproduced from a magnetic tape 3 by a head 1 is supplied to a signal processing circuit 5 via a preamplifier 2 and an A/D converter 4. The control signal given from a control circuit 13 is supplied to an action timing control circuit 142 of a sampling level detector 14. Thus the sampling range is set. The value of a register 15 is varied by the control signal, and the output control voltage of a D/A converting part 8 is varied. Then the capacity of a variable capacity diode 9 is varied and the resonance frequency is varied. A maximum value detecting circuit 141 of the detector 14 monitors the reproduction level in a sampling range and detects the maximum value. The output data of the register 15 is used to obtain a head resonance frequency which is set previously by designing. |
