Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!uxc.cso.uiuc.edu!uxc.cso.uiuc.edu!m.cs.uiuc.edu!irwin
From: irwin@m.cs.uiuc.edu
Newsgroups: sci.electronics
Subject: Re: More need advice on descrambler
Message-ID: <21000033@m.cs.uiuc.edu>
Date: 26 Jun 89 17:10:00 GMT
References: <111777@sun.Eng.Sun.COM>
Lines: 13
Nf-ID: #R:sun.Eng.Sun.COM:111777:m.cs.uiuc.edu:21000033:000:648
Nf-From: m.cs.uiuc.edu!irwin    Jun 26 12:10:00 1989


The point in your illustration where you show the X and say there is
a sine wave there, is known as the color burst. It is a few cycles
of 3.58 Mhz to sync the color. If this is missing from the signal,
color sets think it is a black and white picture and will not trigger
on the color circuits. The color "killer" circuit is triggered by
the presence of this burst.

I have seen black and white pictures, where some video information
in the picture will "fake this" causing the color to trigger on. The
stripes on a referee's shirt at a football game taped in black and
white and then shown on a color set, has been known to trigger the
color on.