[Coco] Bad news, good news...
jdaggett at gate.net
jdaggett at gate.net
Tue Dec 13 23:22:32 EST 2005
By far S-Video would be superior to Composite video.
Tao major problems in composite video demodulation that is
eliminated in S-video is:
1) the color burst phase shifter that is needed to feed the
Chromance demodulator. This will demodulate the I and Q signals
to for the three components of S-Video. R-Y, B-Y and G-Y.
2) the need for the delay line inline with the luminance portion of the
composite signal is eleminated as you do not have the demodulate
the I and Q signals.
There are problems of many variables going out of adjustment
when converting composite video to RGB in a TV. Yes that is what
is happening. The Chromanance info demodulated ends up driving
the grids of the picture tube. The luminance signal drives the
S-Video eleiminates intermediate steps. It also eliminated the
problem of delays through chromanance demodulator circuits. This
eleminates the possibility of minute fractions of a second difference
in arrival of the luminance versus the chromanance signals to the
S-Video preforms in many ways far better than a composite video
signal. Another problem eliminated is the RF modulation and
demodulation that comes when composite video is shoved over an
RF channel. Now you introduce difference between tranmit
frequency, recive frequency, the effect the AFC circuit has on the
signal, and finall more chances for noise introduction.
Separate baseband signals is far more preferred.
On 13 Dec 2005 at 6:23, Boisy G. Pitre wrote:
From: "Boisy G. Pitre" <boisy at boisypitre.com>
Subject: Re: [Coco] Bad news, good news...
Date sent: Tue, 13 Dec 2005 06:23:37 -0600
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
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> On Dec 12, 2005, at 6:35 PM, Stephen H. Fischer wrote:
> > The number of people wanting to use a NTSC S-Video TV to display
> > the output of a CoCo 3 is zero even though the display is really
> > great. My interest in getting a 725 is for non-CoCo 3 use.
> I wouldn't say "zero." I am very interested in seeing how well the
> CoCo 3 projects video to an S-Video supplied television. You claim
> it is comparable to an RGB monitor. If that's the case, an RGB->S-
> Video convertor would be just as desirable as an RGB->VGA convertor.
> -- Boisy G. Pitre boisy at boisypitre.com "Monde, je suis pas venu ici
> pour vous faire de la peine."
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