| 摘要 |
Color picture information is recorded on a video disc together with multiple channels of sound information (e.g., a pair of stereo sound signal components). Each audio signal to be recorded modulates the frequency of a respectively different sound carrier over a respectively different low frequency deviation range. Picture carrier waves are frequency modulated in accordance with composite color video signals, including a luminance component and a chrominance component (the latter comprising a modulated color subcarrier buried in the midband of the luminance component). The duty cycle of the modulated picture carrier waves is varied in accordance with the sum of the respective frequency modulated sound carriers to form a recording signal. The color subcarrier frequency, and the respective sound carrier center frequencies correspond to different odd multiples of half the line frequency. The sound carrier deviation ranges lie below (but near) the band occupied by the chrominance component, and below the first order sideband of the modulated picture carrier. The black-representative picture carrier frequency is separated from the chrominance band upper boundary by a frequency substantially corresponding to the highest video signal frequency. A disc record is developed with a pattern of depressed and non-depressed regions in its groove bottom representative of the recording signal. Playback apparatus recovers from the disc record a playback signal of the general form of the recording signal. Respective bandpass filters, with passbands centered about the respective sound carrier deviation ranges, select playback signal portions for application to respective sound carrier FM demodulators. Additional filter, with passband encompassing picture carrier deviation range and first order sideband therefor, supplies input to picture carrier FM demodulator. Video signal processing circuits, responsive to output of picture carrier FM demodulator, include respective comb filters for selectively passing respective luminance and chrominance components. |
