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From: ajb@mhuxo.UUCP (Andrew Becker)
Newsgroups: sci.electronics,rec.audio
Subject: TV distortion from copy protected video tapes?
Keywords: TV,video,copy protection
Message-ID: <1502@mhuxo.UUCP>
Date: 17 Feb 89 18:40:34 GMT
Distribution: na
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 19


     I have noticed that some commercially produced video tapes produce
a distorted picture and sound track when played on my moderately old
television set; I have no such problem with videos I have taped myself.
     The distortion consists of several rows of white line segements
in the top portion of the screen, slightly left of center, which fade in
and out about once a minute, on average.  The sound track also exhibits
static which fluctuates in and out with the picture as well.
     I have been told that some commercially made videos are incompatible
with older TV sets and produce a bending of the picture in the top section
of the screen.  While this is not the symptom I experience, could there be
some other incompatibility which could create this problem, perhaps from
the copy protection scheme used in commercial videos?
    If this is the likely problem, is there a filter or conditioning device
which can be constructed to fix it?  Thanks for the help.       

                                               ajb!mhuxo
                                               AT&T Bell Labs
                                               Murray Hill, NJ