[QuadList] Gene Kelley Show color recording system

[Phillip G. Shaw]

Question: Why would the chroma not have the same error as the luminance?

How does velocity error show up in monochrome?



I would explain it this way. The Chrominance, when NTSC encoded, is ALL contained "of" the frequency of 3.58 Mhz, it is the Phase of the 3.58 that is modulated. The Color Burst on each line is the reference phase (Plant Sub carrier) used in decoding & error detection systems.



When you make a recording all Quad error exists to luminance & Chrominance equally and may be corrected together.



All error Correction systems "may" be correctly considered "Coarse" (Line rate Comparison) followed by "Fine"  (3.58 Color Burst comparison). 



The comparison of 3.58 color burst (off tape) to plant Sub carrier has a very narrow window. Phase between lines is 180 deg; phase between fields is 90 deg. The Phase of Color Burst is four (4) fields or 2 frames. The 140nsec shift most editors have/had to deal with is difference between frame 1 or 2.  RS170A defines field one of the four field sequence but... but... As my old friend Charlie Spicer would say in his SMPTE papers.. "Nobody can tell if it 12 PM or 12 AM" just by looking at the NTSC Color Burst



Back to the non -phase problem: When you encode chrominance using plant sub carrier you are basically burning-In all error of chrominance. All Quad error exists but you can't see it with your eye or corrected it electronically.



The functional block of a NTSC decoder was not trivial in the Era of quads, remember the one line delay using Glass in the drop out comp. The Non-Standard button must bypass the line-to-line TBC correction but may have allowed burst 3.58 correction; again that correction is limited unless line correction is done first.



The First demod/re-mod solution to non-phase error was provided by after market TBC's for Umatic, in about 1978-79.  Those gave way to hi-end GRB decoding with color-correction & all the feature sets, these can be used on all NTSC encoded signals.



RE: TRC100A question. The last 7 machines where delivered to NBC-NYC in ~ 1985. These replaced the existing TCR's of 3rd & 4th shop order. The 7th shop order was TCR100A & SP100A. The Machines where delivered Standard MONO 70 mil, but upgraded on site by RCA

to Stereo Split track (2 ea, 25Mil plus guard band). The EPIS (electronic program ident system) was transferred from old to new. I was the NBC BSE Project Engineer 

Note: I salvaged some mono 70 mil heads & one set of old interconnect cables (SP100 toTCR).



Just a comment Re: Audio Quality & Picture to Sound timing.  Audio quality is normally a function/limitation of the TAPE not electronic or copper limitations. The days of quad had near Zero audio to video delay within plants. The invention of Digital affects introduced the frame of delay.. and then video frame syncs. Audio delays followed in ~ about 1987-88 and the Electronic Clap board feature in the TEK- VM700 



That's my memory,
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