| 摘要 |
PURPOSE:To control correctly tracking of a rotary head without being influenced by the mechanical secular change of a device, the temperature change or jittering at the time of double speed reproduction by forming a sampling pulse on the basis of the reproduced output of a pilot signal recorded in the center part of a track every scanning period of each head. CONSTITUTION:A signal taken out from a tape by the rotary heads 1A, 1B is alternately switched by a switching circuit 19 every half rotational period, only a pilot signal is extracted by a band pass filter 20 and its detected output is supplied to sample holding circuits 22, 23. The edge of each pilot signal located on the initial position is detected and a signal S7 is generated. An AND circuit 27 passes only the signal S7 inputted during the period of a window signal S8 and a sampling pulse generating circuit 29 supplies a pair of sampling pulses SP1, SP2 having a phase difference each other to the sample holding circuits 22, 23. An output difference between the sample holding circuits 22 and 23 is taken out from an output terminal 25 as a tracking control signal. |
