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Old 06-19-2018, 12:59 PM
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Penthode Penthode is offline
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Join Date: Jun 2009
Location: Kitchener/Waterloo Ontario Canada
Posts: 1,059
I believe the line is a function of the cheaper consumer baseband analog sync generation. The sync pulse edges have too fast rise and fall times and the video peaking to secure sharp edges in absence of later B&W sets video bandwidth (2.5 to 3.0 MHz) exacerbates the problem.

Late 50's, early 60's B&W sets seem to be the worst offenders. My late 40's RCA B&W sets with 4MHz full bandwidth have no problem in this regard.

A minor modification adding a horizontal retrace blanking circuit should fix this. Or using a device which generates sync following the 140ns +/- 20ns rise and fall times of the SMPTE 170M specification.
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File Type: jpg NTSC Horizontal Blanking.jpg (54.5 KB, 21 views)

Last edited by Penthode; 06-19-2018 at 01:12 PM.
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