17 Dec
2007
17 Dec
'07
4:08 p.m.
In particular those used in NTSC sets are to balance
the delays in the chroma
circuits (those that are on the 3.579 sub carrier) with the luma signal (which
isn't processed). Since the chroma goes thru additional circuits, the other
signal needs to be delayed (not very long) to maintain the registration. In
PAL sets, I believe that the same idea is used. The difference is that in PAL
It is, but that's not the delay line I'm talking about. Look up the
design of a PAL-D decoder (D = Delay) and see how a
just-less-than-1-line-time delay line is used to store onoe fo the clour
difference signals.
sets a different subcarrier frequency is used, and the
demodulation products
are different for every other line (they swap In-phase, and Quadrature). SECAM
is a bit different, as they do NOT use in-phase and quadrature (simultaneous)
demodulation of the color difference signals, but alternate them line by line
(The 'S' in SECAM). This necessitates a one line delay to keep around the
I thought SECAM was 'Systeme Electronique Couleur Avec Memoire' (?Spel)
The 'M' referes to the delay lien acting as a 1-line time memory to store
one of the colour difference signals I think.
-tony