| 摘要 |
PURPOSE:To prevent the interference of the pull-in of a tracking servo and the attacking time of an AGC circuit with each other when the operation mode is shifted to the playing mode, by providing a gain controlling circuit which fixes the amplitude of reproduced pilot signals and a circuit which cuts off the control voltage of a control circuit. CONSTITUTION:Four kinds of pilot signals, whose frequencies circularly change at every tracks, are recorded on each recording track of a magnetic tape 1 together with information signals. Reproduced signals from heads A and B are supplied to an AGC circuit 4 through a switch SW1 which is switched by an RF switching pulse impressed upon a terminal 2. The output of the circuit 4 is inputted in a multiplier circuit 6 and the output of a reference signal generating circuit 7 is impressed upon another input of the circuit 6. Tracking control is performed by means of the output of an amplifier 8 and a detecting circuit 21 supplies a control voltage having a prescribed attacking time and recovery time to the circuit 4. When shifting to the playing mode, the control voltage is cut off by a switch SW2 and interference of the pull-in of a tracking servo and the attacking time of the AGC circuit with each other can be prevented.
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