| 摘要 |
In a video disc player, a first FM signal recovered from the disc is subject to frequency demodulation to obtain a composite color video signal, and a second FM signal recovered from the disc is also demodulated to obtain an accompanying sound signal. The player includes a defect detector, monitoring the first FM signal to identify carrier frequency departures from the intended deviation range, and switching apparatus for effecting a substitution of stored video signals, in replacement of the output of the video FM detector, when the defect detector identifies such departures. A squelch control signal generator is rendered responsive to an output of the defect detector, and develops a squelch signal when the defect indication persists beyond a predetermined minimum length of time. The squelch signal is employed to inhibit the passage of sound and video signals to player output terminals. The squelch control signal generator is additionally rendered responsive to player apparatus controlling placement of the player stylus in and out of playback position (e.g., controlling lowering/lifting of stylus arm), so that removal of stylus from playback position initiates squelch signal development without need for passage of said predetermined minimum length of time. |
