NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/rec/radio/shortwav/9025

Text File | 1993-01-01 | 4.1 KB | 79 lines

Newsgroups: rec.radio.shortwave
Path: sparky!uunet!paladin.american.edu!darwin.sura.net!jvnc.net!adx.adelphi.edu!auvax1.adelphi.edu!schmidt
From: [e-mail]
Subject: Re: RICV radio (for the blind) - need info
Message-ID: <[e-mail]>
Lines: 66
Sender: [e-mail] (USENET News System)
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Organization: Adelphi University, Garden City NY
References: <[e-mail]>
Date: Fri, 1 Jan 1993 07:31:32 GMT

In article <[e-mail]>, [e-mail] (Steve Masticola) writes:
> Hi,
>
> Does anyone have any information on a local-area broadcast service for
> the blind, called (probably) RICV? My father asked me to find out.
> Other than that it operates only around U.S. cities and has short
> range, I have no other information.

Most of these operations are FM SCA operations, broadcasting using the SCA of
local FM stations, often educational stations.  Receivers are usually available
from the operator of the service.  The local service organizations for the
blind can probably direct you to the source.  I think they often loan the
receivers to blind people free.

As you may figure out from many of the postings recently, this provides an
additional channel of audio to an FM station, similar to the SAP of a TV
station, except that it is "private", and is not built into ordinary receivers
as the SAP is in most stereo TV's  You get the receiver, usually fixed
frequency, at least in SCA mode (most will also pick up the regular "baseband"
FM signals also)  from the service originator or their designee.  It is
considered a private point to multipoint broadcast service.  The original use
was mostly for transmitting "MUZAK" and such to stores and businesses.  There
were also early attempts to use it for a broadcast fax service, some years ago,
for delivering newspapers, but that idea failed economically (try reading the
New York Times printed on fax paper!!)  Now SCA's are used for "narrowcasting",
such as the blind reading service, some teaching for doctors, a service aimed
at Haitians called "Radio Tropicale" (studios about a mile from here)  and
such.  Also data services, such as stock market reports.  We got our UPI
service here thru an SCA rented by a data common carrier who (by contract with
UPI) carried it in their bitstream.  Beepers, particularly some of the
"nationwide" services, also have used SCA's in some cases.

The ECPA makes it illegal to listen to an SCA without the permission of the
service provider.  Hard to enforce, though, unless you are stealing "MUZAK" and
pipeing it into your store. :-(

Since the SCA's use, in most cases, subcarriers with low deviation and low
injection, to avoid degrading the main channel signal of the station, they are
not full fidelity services, kind of "AM" quality or so, and the coverage is
less than that of the station they are piggybacked on, kind of like stereo
compared to mono, only quite a bit worse, as far as service area reduction is
concerned.  Also most SCA receivers restrict the reproduced bandwidth to reduce
crosstalk from the main channel.

There are extensive FCC rules concerning the transmitting of SCA's, which I
posted excerpts from here (or was it in r.r.b, I forget?) last summer.  You
might look in the archives if you are interested.

Providing SCA's can be quite profitible to FM stations.  One "class B"
educational FM in New York gets about $80,000 per year in income from renting
one sca, and you can squeeze two in on top of the stereo signal.

John


>
> Thanks for any help,
> - Steve Masticola ([e-mail])
>   Formerly WA3RQH, now KF2IO
--
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John H. Schmidt, P.E.              |Internet: [e-mail]
Technical Director, WBAU           |Phone--Days     [phone]
Adelphi University                 |       Evenings [phone]
Garden City, New York 11530        |Fax-------------[phone]
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