[QuadList] Gene Kelley Show color recording system

[C. Park Seward]

Thanks, Phillip. Excellent discourse.

One of my 1200s has a NEC TBC and does an excellent job fixing  
velocity errors. I will restore next a 1200B with the standard Ampex  
Amtec, Velcomp and Colortec.

Best,
Park

C. Park Seward
Visit us: http://www.videopark.com



On Jan 2, 2009, at 3:16 PM, Phillip G. Shaw wrote:

> 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.
>
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