The Video Return-Loss Bridge

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Publisher: SMPTE — White Plains, NY, USA
Doc Type: Journal Article
Content Type: Original Research
Abbreviated Title: J SMPTE
Volume: 77, No. 8, pp. 794–798
Abstract: The accurate measurement of impedance errors which cause television signal degradation is important in distribution systems of broadcast studios and network facilities. Methods of measurement which use impedance bridges or other devices are generally time consuming and no one device will yield complete data over the whole video-frequency spectrum. An alternative technique which has become popular in other countries is to measure impedance error in terms of return loss. With respect to transmission lines, return-loss is defined as the ratio of the incident signal to the reflected signal expressed in decibels. The return-loss concept may also be extended to measure impedance errors of two terminal devices. A new version of a return-loss bridge uses a high-gain, wide-band oscilloscope differential preamplifier as the error detector. The characteristics of this bridge are: (a) passive components, (b) extremely simple construction and (c) great sensitivity and bandwidth. With this bridge a single measurement can cover the complete video spectrum. Return-loss errors of 60 dB can be measured over the bandwidth of 0 to 8 Mhz.
Publication Date: 1968-08-01
DOI: 10.5594/J06984
ISSN: Print: 0361-4573
Link: https://doi.org/10.5594/J06984
Author(s): E. H. FriedmanEngineering and Development Dept., CBS Television Network, 51 West 52d St., New York, N.Y. 10019
Frank DavidoffEngineering and Development Dept., CBS Television Network, 51 West 52d St., New York, N.Y. 10019
Copyright: © 1968 Society of Motion Picture and Television Engineers, Inc.

Bibliographic Reference(s)

1. LePage W. R. Seely S. , General Network Analysis , McGraw-Hill Book Co. , New York , 1952 , p. 308 . EXTERNAL
2. Weaver L. E. , “The Measurement of Return Loss,” Designs Department Technical Memorandum , No. 9.10 (60), British Broadcasting Corporation . EXTERNAL
3. Thiele A. N. , “Return Loss Bridge for Video Frequencies,” Laboratory Report No. 17, Engineering Division, Australian Broadcasting Commission . EXTERNAL
4. Butt A. J. Iles G. D. , “Two new waveform generators for television testing,” Jour. SMPTE , 74 : 1012 , Nov. 1965 . EXTERNAL

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E. H. Friedman and Frank Davidoff; The Video Return-Loss Bridge, Journal of the SMPTE ( Volume: 77, Issue: 8, August 1968); SMPTE, 1968. Available at https://doi.org/10.5594/J06984

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E. H. Friedman and Frank Davidoff; The Video Return-Loss Bridge, Journal of the SMPTE ( Volume: 77, Issue: 8, August 1968); SMPTE, 1968. Available at https://doi.org/10.5594/J06984

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E. H. Friedman and Frank Davidoff; The Video Return-Loss Bridge, Journal of the SMPTE ( Volume: 77, Issue: 8, August 1968); SMPTE, 1968. Available at https://doi.org/10.5594/J06984

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<span class="citation">E. H. Friedman and Frank Davidoff; <cite>The Video Return-Loss Bridge</cite>, Journal of the SMPTE ( Volume: 77, Issue: 8, August 1968); SMPTE, 1968. Available at <a href="https://doi.org/10.5594/J06984" target="_blank" rel="noopener">https://doi.org/10.5594/J06984</a></span>

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E. H. Friedman and Frank Davidoff; The Video Return-Loss Bridge, Journal of the SMPTE ( Volume: 77, Issue: 8, August 1968); SMPTE, 1968
doi: 10.5594/J06984
url: https://doi.org/10.5594/J06984

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<span class="doi">10.5594/J06984</span>
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