Sanyo Electric Co., Ltd.

Hiroyoshi Hashimoto

Ichiro Takahara

A stabilizing circuit for a phase locked loop comprising an input terminal for receiving an input pulse signal, a voltage controlled oscillator, a phase comparator for comparing the phases of the input pulse signal and the output of the voltage controlled oscillator, and a low pass filter for filtering the output of the voltage controlled oscillator for providing a voltage control signal to the voltage controlled oscillator, characterized in that the stabilizing circuit comprises a random noise source for generating a random noise input to the input terminal which has a frequency sufficiently high with respect to the frequency of the normal input pulse signal, a switching circuit preliminarily applying the random noise input to the input terminal and responsive to the normal input pulse signal for selectively applying the normal input pulse signal to the input terminal, and an adjusting circuit for adjusting the input of the voltage controlled oscillator when the random noise input is received to a level close to the input level of the voltage controlled oscillator when the normal input pulse signal is received, whereby the operation of the phase locked loop is stabilized in a short time period after the normal input pulse signal is received.

Stabilizing circuit for phase locked loop

A jitter correcting system is provided in a video reproducing apparatus for reproducing a composite video signal of a given standard television system to be connected to a monitor television receiver including an automatic frequency control for a horizontal oscillator, comprising a circuit for phase modulating the horizontal synchronizing signal of the reproduced composite video signal, by the amount associated with the phase difference between the composite video signal to be applied to the picture tube of the monitor television receiver and the output signal of the automatic frequency control of the monitor television receiver, for providing a modified composite video signal a phase modulated horizontal synchronizing signal. The system further comprises a circuit for generating a pseudo video composite signal including vertical and horizontal synchronizing signals and a marking signal in the video signal phase region wherein the horizontal synchronizing signal has been phase shifted as compared with that of the standard television system of the video reproducing apparatus for applying the said pseudo composite video signal through the jitter correcting system to the monitor television receiver, whereby the phase modulating circuit can be adjusted while observing the marking indication caused by the marking signal appearing on the screen of the picture tube.

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Neyagawa, Japan

Hiroyoshi Hashimoto