| 摘要 |
<p>A method and apparatus for developing a compressed bandwidth frequency modulation signal format to increase the playing time per side of a videodisc by compressing the signal bandwidth of the recorded information preferably by a factor of two. Method and apparatus are described and shown for modulating a carrier signal with a color video signal, modulating a subcarrier frequency with at least one audio frequency signal, selecting the carrier and subcarrier frequencies such that the upper frequency deviation limit of the frequency modulated carrier signal is lower than the useful upper frequency limit of the recording medium chosen for the disc, and such that there is no overlap of the chroma baseband signal and the second order chroma sideband. At least one audio subcarrier frequency is located between the first order chroma sideband and the chroma baseband signal, or between the chroma baseband signal and the second order chroma sideband, or between the second order chroma sideband and DC. Preferably, the maximum FM carrier frequency, the blanking level FM carrier frequency, the white level FM carrier frequency, and the horizontal sync tip FM carrier frequency, are all one-half the respective frequencies of a full-luminance/full-color carrier signal.</p> |
