Method and apparatus for PCM-encoding NTSC color television at sub-Nyquist rate
AssigneeCBS Inc.
InventorJohn P. Rossi
Life of this patent
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Abstract
NTSC television signals are digitally encoded at sub-Nyquist rates by placing the alias components into those parts of the spectrum not normally occupied by the luminance or chrominance components of the video signal. In a system described, the sampling frequency, f.sub.s, is exactly 2f.sub.sc + 1/4f.sub.h or 2f.sub.sc - 1/4f.sub.h, where f.sub.sc is the NTSC color subcarrier frequency and f.sub.h is the line-scan frequency. Most of the alias signals in the thus encoded signal are removed from the baseband video by comb filtering between f.sub.s - f.sub.y and f.sub.v, where f.sub.v is the baseband video bandwidth.
Claims9
A method of digitally encoding an NTSC color television signal having a color subcarrier frequency f.sub.sc and a line-scan frequency f.sub.h, comprising the steps of:
- generating a first sampling signal having a frequency f.sub.s that differs from 2f.sub.sc by 1/4f.sub.h,
- sampling the television signals in response to the sampling signal, and
- converting the sampled television signal into digital form.
Apparatus for digitally encoding an NTSC color television signal having a color subcarrier frequency f.sub.sc and a line-scan frequency f.sub.h, comprising, in combination,
- means for generating a first sampling signal having a frequency f.sub.s differing from 2f.sub.sc by 1/4f.sub.h,
- means for sampling the television signals in response to the sampling signal, and
- means for converting the sampled television signal into digital form.
Dependencies are inferred from the claim text.