| 摘要 |
PURPOSE:To decrease jitters of a reproducing signal and an erroneous locking probability by servo-locking a reproducing device at a field frequency, odd- dividing one frame, comparing in phase with a reference frame, discriminating two servo-locking phases and shifting the servo system phase at the time of one-side, is locking in phase. CONSTITUTION:A reproducing timing pulse H is introduced to a 2.5H window generating circuit 4 and a window pulse D is generated. Next, the window pulse D is supplied to a phase deciding circuit 5, the level of D is sampled by the rise of a reference frame pulse E. The deciding output is supplied to a pulse generating circuit 8 and one prescribed width servo-shifting pulse S is guided. The servo shifting pulse S is supplied to a VTR 1 and overlapped and added to the driving voltage of the input of the driving circuit of a capstan motor. As the result, the rotating phase of the capstan motor is instantaneously shifted and a servo locking phase is fixed to the phase of (a). As a result, the phase of the reproducing signal always synchronizes to the reference frame pulse from a reference oscillator 6 and the jitter quantity is reduced by half.
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