Path: utzoo!attcan!uunet!snorkelwacker!think!zaphod.mps.ohio-state.edu!uwm.edu!agcb8.larc.nasa.gov!kludge
From: KLUDGE@AGCB8.LARC.NASA.GOV (Scott Dorsey)
Newsgroups: rec.audio.high-end
Subject: VHS Copy Code
Message-ID: <900315081159.22800935@AGCB8.LARC.NASA.GOV>
Date: 15 Mar 90 14:00:19 GMT
Sender: news@uwm.edu
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Approved: tjk@csd4.csd.uwm.edu


One of the older copy protect systems used on VHS tapes was a very low
frequency (1 to 5 Hz) component added to the video signal, which would
have a tendency to mess up the synch stuff on video recorders, as well\
as overdriving the heads.  It didn't work very well, everybody bought
small high-pass filters to defeat them, and it's probably still being
used somewhere.  Unfortunately, it would mess up a number of television
sets, as well.

Disclaimer: I don't do video.  I don't even own a TV set.  I do have a 
            two-projector 16mm rig in my living room, though.

--scott