Path: utzoo!attcan!uunet!mcvax!ukc!dcl-cs!nott-cs!pyr1.cs.ucl.ac.uk!william
From: william@pyr1.cs.ucl.ac.uk
Newsgroups: sci.electronics
Subject: Re: VCR comercial eliminator
Message-ID: <44000022@pyr1.cs.ucl.ac.uk>
Date: 1 Sep 88 11:47:00 GMT
References: <257@ivucsb.UUCP>
Lines: 27
Nf-ID: #R:ivucsb.UUCP:-25700:pyr1.cs.ucl.ac.uk:44000022:000:1346
Nf-From: pyr1.cs.ucl.ac.uk!william    Sep  1 11:47:00 1988


In the UK it is possible to detect commercials by the fact that there
is often a minor signal break as the transmitted program switches
from one film to the other.  I used to have an ITT colour TV which
had a blown rectifier circuit (or was it a dead valve?  ITT sets of 
1974 vintage usually suffered from these failures) which caused the
green gun to click into the red signal, and so reds and greens
would get swapped:
1.	If you jumped up and down near the TV,
2.	If you switched channels,
3.	When the ads came on or went off.
Some days it would go bad during a film, defy all attempts to get it
right, then click into normal mode when the ads came on, and then go bad
again when the film returned!

My father used to work for the Post Office TV networking section, and
I recall him saying that they used to have a guy sitting there looking
at his watch, and swapping the plugs when a new program was due to come
on.  I am sure this would throw enough crap onto the signal to be detectable!

			... Bill

************************************************************************
Bill Witts, CS Dept.     *    Nel Mezzo del cammin di nostra vita
UCL, London, Errrp       *    mi ritrovai per una selva oscura
william@uk.ac.ucl.cs(UK) *    che la diritta via era smarrita.
william@cs.ucl.ac.uk(US) ***********************************************