Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!csd4.csd.uwm.edu!rick
From: rick@csd4.csd.uwm.edu (Rick Miller)
Newsgroups: sci.electronics
Subject: Re: detecting TV commercials, is it possible?
Summary: Chopped Audio
Message-ID: <78@uwm.edu>
Date: 15 Sep 89 14:29:04 GMT
References: <4482@natinst.natinst.com>
Sender: news@uwm.edu
Reply-To: rick@csd4.csd.uwm.edu (Rick Miller)
Organization: University of Wisconsin-Milwaukee
Lines: 17

In article <4482@natinst.natinst.com> (Jerry E. Sullivan) writes:
>Is it possible to detect impending commercials in TV broadcasts electronically?
>I suspect some kind of inaudible tones might be present. If there are such
>signals, are they filtered before they reach my home? If there is a signal,
>whre might I find out its exact nature?
>

	"Radio Electronics" had an article on how to 'blank out' commercials
from FM radio broadcasts a while back.  It's based on the fact that advertisers
want very badly to be HEARD, so they often use somewhat distorted signals to
get a higher apparent volume.  They do this by amplifying the signal so that
it's clipped to a certain degree, but not too noticably.

	I've noticed that TV commercials tend to seem louder too, so this
same sort of detector should work.

								Rick