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From: ISW@cup.portal.com (Isaac S Wingfield)
Newsgroups: sci.electronics
Subject: Re: Electronic Pest Control
Message-ID: <20728@cup.portal.com>
Date: 25 Jul 89 06:04:22 GMT
References: <12726@well.UUCP> <6591@cognos.UUCP>
Distribution: na
Organization: The Portal System (TM)
Lines: 20

David Borowski writes:
I don't normally correct but! tv horizontal scan is 15750 HZ 30*525 scan lines 

Well, actually, this is correct for B&W only, and we don't get much of
that any more...

The horizontal scan rate for NTSC color is 15734.26 Hz or thereabouts.
The vertical rate is 59.94, and both are exact submultiples of the
color subcarrier, at 3579545 Hz.

The reasons for this have to do, at least partly, with attempts
to minimize interference between video and audio by controlling
the video signal spectrum. By locking everything together, most
of the energy is in a "comb", and the sound subcarrier fits neatly
in between.

Regards, Isaac


isw@cup.portal.com