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From: wmartin@brl-tgr.ARPA (Will Martin )
Newsgroups: net.audio
Subject: Re:  eavesdropping on FM subcarriers
Message-ID: <7636@brl-tgr.ARPA>
Date: Tue, 22-Jan-85 14:24:20 EST
Article-I.D.: brl-tgr.7636
Posted: Tue Jan 22 14:24:20 1985
Date-Received: Sat, 26-Jan-85 05:47:48 EST
Distribution: net
Organization: USAMC ALMSA
Lines: 45

FM SCA listening is fun and sometimes worthwhile. One of the best source
for info on the subject is the FM Atlas people. Their address is simple:
FM Atlas, Adolph, MN 55701 (a personal effort by Dr. Bruce Elving). I've
bought a couple SCA decoders from them, and a radio with a built-in
decoder and switch, which I gave to my mother as a present. They sell
a fancy decoder from Capri Electronics for $98, which has tunable
subcarrier dectection up to several hundred kHz or so. I bought one,
as their price was lower than direct from Capri ($114 there) and also 
some "security" or "anti-bugging" firms were selling the same box for
over $200! (You can switch it to listen off the power line, too, to
detect wireless intercoms or bugs using that technique.) You can buy
a simple SCA decoder kit and build it in most FM radios for $20 or $25,
which is a cheaper way to go, or buy one of their SCA-equipped radios
if you didn't want to muck about in the innards of one. Their prices
are fair for the radios, I think.

Anyway, of course most of what you hear is Muzak, which isn't worth
paying for, in my opinion. There are some music services which have 
less elevator-like music than Muzak, though, which might appeal to you.
I've never heard one of these adaptors, though, that really filter out
the base program well enough to pipe the result into a hifi system,
which would be about the only way "background music" would be of use
in most home environments. If the sound from a portable radio is good
enough, though, this would be worthwhile.

Other things you hear: Physicians' News Service, a program of medical
news directed at MDs, laden with drug ads. Could be bizarre to listen
to for a while, but soon tiresome. Farm news & agricultural commodity
info; once you've heard the price of pork, will you want to hear it
again? Services for the blind: this is the really worthwhile service.
They read the newspaper (you could listen to the paper while driving,
if that interests you) and sometimes read books or magazines. Data:
a lot of you out there might want to play with this. Some data transmissions
are transmitter-to-studio links, just giving the station its own meter
readings. But some is commodity or stock prices, probably encrypted,
the access to which is sold, along with the decoding equipment, in some
major cities. 

Look in your local libraries for the latest (9th) edition of the FM
Atlas for more information on stations transmittng SCA and SCA in general.

Regards,
Will Martin

ARPA/MILNET: wmartin@almsa-1.ARPA     USENET: seismo!brl-bmd!wmartin