Sub-Nyquist-Encoded PCM NTSC Color Television

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Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
Abstract: Where a channel has a limited data rate or a digital store has a limited capacity, it is sometimes essential to reduce the data rate of pulse-code-modulated color television signals. One direct way of doing this is to lower the encoding frequencyfs, but the Nyquist sampling limit is soon reached and further reduction results in beat distortions due to “alias components” when the lower sidebands of fs overlap the baseband video frequencies. NTSC television signals can be 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. By the proper choice of comb filters (two types are specified), most of the alias signals can be removed from the baseband video. In the system examined, fs is exactly 2fsc + 1/4 fh or 2fsc — 1/4fh, where fsc is the NTSC color subcarrier frequency and fh is the line-scan frequency. Comb filtering is done between fs — f, v and fv where fv, is the baseband video bandwidth. Frequency response equalization is performed within the comb-filtered frequency band. Two modifications to the basic system were studied: using constant vertical quadrature phase sampling and performing comb filtering prior to digital encoding. Color slides and test waveforms encoded by this technique were viewed and found to be subjectively acceptable.
Publication Date: 1976-01-01
DOI: 10.5594/J07599
Link: https://doi.org/10.5594/J07599
Author(s): John P. Rossi

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John P. Rossi; Sub-Nyquist-Encoded PCM NTSC Color Television, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976. Available at https://doi.org/10.5594/J07599

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John P. Rossi; Sub-Nyquist-Encoded PCM NTSC Color Television, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976. Available at https://doi.org/10.5594/J07599

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John P. Rossi; Sub-Nyquist-Encoded PCM NTSC Color Television, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976. Available at https://doi.org/10.5594/J07599

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<span class="citation">John P. Rossi; <cite>Sub-Nyquist-Encoded PCM NTSC Color Television</cite>, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976. Available at <a href="https://doi.org/10.5594/J07599" target="_blank" rel="noopener">https://doi.org/10.5594/J07599</a></span>

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John P. Rossi; Sub-Nyquist-Encoded PCM NTSC Color Television, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976
doi: 10.5594/J07599
url: https://doi.org/10.5594/J07599

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<li>
John P. Rossi; <cite id="bib-10-5594-j07599">Sub-Nyquist-Encoded PCM NTSC Color Television</cite>, SMPTE Journal ( Volume: 85, Issue: 1, January 1976); SMPTE, 1976
<span class="doi">10.5594/J07599</span>
</li>