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From: plate@dicome.UUCP (Douglas B. Plate)
Newsgroups: sci.electronics
Subject: Re: FM audio recording?
Message-ID: <1588@dicome.UUCP>
Date: Tue, 22-Sep-87 10:30:28 EDT
Article-I.D.: dicome.1588
Posted: Tue Sep 22 10:30:28 1987
Date-Received: Sat, 26-Sep-87 07:49:51 EDT
References: <3746d52b.b8ab@apollo.uucp> <231@piglet.UUCP> <1574@dicome.UUCP> <235@piglet.UUCP>
Reply-To: plate@dicome.UUCP (Douglas B. Plate)
Organization: DICOMED Corp., Minneapolis
Lines: 38

Newsgroups: sci.electronics
Subject: Re: FM audio recording?
Summary: 
Expires: 
References: <3746d52b.b8ab@apollo.uucp> <231@piglet.UUCP> <1574@dicome.UUCP> <235@piglet.UUCP>
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Reply-To: plate@dicome.UUCP (Douglas B. Plate)
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Organization: DICOMED Corp., Minneapolis
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In article <235@piglet.UUCP> sjb@piglet.UUCP (Seth J. Bradley) writes:
)In article <1574@dicome.UUCP), plate@dicome.UUCP (Douglas B. Plate) writes:
)) In article <231@piglet.UUCP> sjb@piglet.UUCP (Seth J. Bradley) writes:
)) )ungodly bandwidth FM requires.  15KHz stereo broadcasts use about
)) )160 KHz of bandwidth, and it would be difficult, if not impossible,
)) Just to clarify:
)) "An FM broadcast channel is 200kHz wide."  
)) -Electronic Communication,  Robert L. Shrader  (my tech school text book).
)) 
)) 		Doug Plate
)
)I cannot find my reference just now, and perhaps the radio buffs out
)there can clarify.  Although FM broadcast channels are spaced 200KHz
)apart(which is obvious just looking at the dial)  there exist in that
)channel guard bands, pilot signals, and subbands.  I believe(and if anyone
)out there knows differently they are welcome to correct me) that the
)actual audio portion of the main FM band takes up around 160 KHz.

OK, I should have included the entire reference from the book.  You're
very close.  The sound itself deviates 75kHz either side of center
frequency at 100% modulation (150kHZ) and there is a 25kHz guard band
on each side (another 50kHz=200kHz total).  I guess I zoomed in on
the words "stereo broadcasts use" and forgot that that we were actually
talking about FM being put on to tape.  Sorry.  
		Doug Plate
(info given here was taken from the same book sited above)