Abstract: In an optical disk device, an output terminal is connected to an optical pickup, and a preceding sub-beam returning light signal which is electrical signal obtained by converting returning light of a sub-beam preceding an main beam is output through the output terminal. A defect period detection circuit detects a defect period during which a beam is passing through a defective portion on an optical disk based on the preceding sub-beam returning light signal from the output terminal. A servo hold circuit holds tracking servo during the detected defect period. Therefore, even when an amplitude of an RF signal is quickly attenuated during the defect period, the defect period is detected at an early stage of the attenuation, thereby suppressing a change in an amplitude of a tracking error signal to a small level.

Abstract: A signal processing apparatus for use in a video cassette recorder comprising a pilot burst gate pulse generating system means responsive to horizontal synchronizing signals successively generated in correspondance with horizontal scanning periods to process the horizontal synchronizing signals so as to produce pilot burst gate pulses. The pilot burst gate pulse generating system is responsive to a first horizontal synchronizing signal to generate the pilot burst gate pulse at a timing delayed by a predetemined time period from a leading edge of a second horizontal synchronizing signal following the first horizontal synchronizing signal. This arrangement allows stable generation of the pilot burst gate pulse at a timing slightly delayed from the active edge of the corresponding horizontal synchronizing signal.

Abstract: A video signal processing apparatus has a phase-locked loop which includes a quartz resonator, a voltage-controlled oscillator connected to the quartz resonator and oscillating at an oscillation frequency whose fundamental value is determined by the quartz resonator, and a horizontal sync signal lock circuit comparing a phase of a horizontal sync signal and a phase of an output signal from the voltage-controlled oscillator and controlling the oscillation frequency of the voltage-controlled oscillator in response to a difference between the phases of the horizontal sync signal and the output signal from the voltage-controlled oscillator. The video signal processing apparatus also has a device for modulating a video signal by use of the output signal from the voltage-controlled oscillator.