[opendtv] Re: Food for thought

What bearing or force does ANSI/SMPTE 170M-1994 [SMPTE 1267, April 19, 1996] have on this discussion? 


Mark Schubin wrote:


It was published in IETS-1 in November 1977.

TTFN,
Mark


Barry Brown wrote:


Mark,
Almost but may not be not completely right - There was no RS-170A standard published by EIA, but I'm almost positive the RS-170A waveform spec was published. I know because I spent some years (don't remember how long) working on this drawing. 

Barry Brown


On Feb 17, 2007, at 2:22 PM, Mark Schubin wrote:


John Willkie wrote:


Now, you've got me confused, Mark.


It's an interesting quirk of fate.

NTC-7 is real.  RS-250B and EIA-250C are real.
There was never any such standard as RS-170A. There certainly was an RS-170 for monochrome TV, and there is agreement on what RS-170A would have been, had there ever been one. But broadcasters did not want to create an RS-170A until they were ready for it, lest the FCC adopt it as part of the rules and they be fined for violating them.
So, instead, there is EIA IETS-1 (the first, and possibly only, Industrial Electronics Tentative Standard), which specifies the subcarrier-to-horizontal-sync relationship that everyone thinks comes from the non-existent RS-170A. 

TTFN,
Mark








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