Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!bunker!hcap!hnews!129!89.0!David.Andrews
From: David.Andrews@p0.f89.n129.z1.fidonet.org (David Andrews)
Newsgroups: misc.handicap
Subject: Re: RADIO QUESTIONS
Message-ID: <12993@bunker.UUCP>
Date: 20 Jul 90 20:22:07 GMT
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[This is from the Blink Talk Conference]

 BK> David, thanks for your help. First, I'm glad that someone got  
 BK> my message about the radio reading service project.  I guess  
 BK> that my question would be that he wants to send the service via  
 BK> phone lines to K Krma in Denver. What kind of quality would you  
 BK> say we can expect with that set up.  
 

Bill,  A phone line relay would not be my first choice.  A phone
line is limited to between 3000 and 5000 hertz.  A regular FM
sub-carrier service goes to just above five KHZ and the regular TV
SAP can theoretically go to about 8.5, but is more realistically 5
to 6.  The phone line relay would degrade the signal quality in
Denver, noticably.

BK> By the way, The service will be run from Boulder, or so I've  
 BK> been told. I guess that my other question would be how does a  
 BK> service like that buy radios? Are there grants easily available  
 BK> for such a program, or what. 
 

The main source of money, for radios and studio equipment besides
state money, or locally raised funds is from a federal program
called the Public Telecommunications Facilities Program, (PTFP)
administered by the National Telecommunications and Information
Administration of the Department of Commerce.

The grants are issued once a year, and applications are usually due
in January.  I talked to Dave Dawson about this program at length.
They also have planning grants.

BK> Also, as I've listened to other  
 BK> services like the one near Belleville Ilinois, I'm concerned  
 BK> about the crosstalk. Is there less likelihood of that when you  
 BK> use a tv frequency? Thanks for your help, and thanks for  
 BK> picking up on this message. Bill K. 
  

The crosstalk to which you refeer is a by-product of the FM
sub-carrier most reading services use.  It can be lessened to a
certain extent, by injecting the sub-carrier signal into the main
carrier at the proper level, tuning the antenna properly, having
well designed receivers, and moving the receiver in your room,
and/or re-orienting the antenna.  However, some is always going to
exist.  Further, it will vary some, from day to day, depending on
the weather.  The TV SAP services have considerably less
crosstalk.  Further the frequency response and dynamics are also
better.  However, the propagation of the signal is different.  If
you are at a close or medium range, it is great, but as you go out,
signal quality degrades markedly, much more so, and much quicker
then with FM SCA.  It is also very susspetible to interfeerence
from trees, buildings etc.

I started a service in New Jersey, in Trenton in 1984.  We were the
first audio service of any kind in the country to use TV SAP, so I
have had experience with it.  We had a listener who got a bid
signal on windy days.  It turned out that she was a considerable
distance from our transmitter, and on windy days a tree had shaking
limbs outside her house.  Their movement affected her signal.
David Andrews

... Your Sound Alternative

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