David.Andrews@p0.f89.n129.z1.fidonet.org (David Andrews) (07/21/90)
Index Number: 9383
[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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Internet: David.Andrews@p0.f89.n129.z1.fidonet.orgDavid.Andrews@p0.f89.n129.z1.fidonet.org (David Andrews) (07/27/90)
Index Number: 9552
[This is from the Blink Talk Conference]
BK> David, thanks for your complete post. I was hoping you might go
BK> to some length in sanswering. As I sit here thinking, how would
BK> cable affect the signal from a tv sca? For instance, Boulder is
BK> 30 miles away from Denver where the tv channel is. Can you
BK> guess how the signal might be from my location?
I am not sure I understand the question, but I think it is, how would my
reception of a TV SCA be from 30 miles away. Well, there are variables, of
course, such as antenna height, power, and receiver location, but 30 miles is
starting to get on the fringe a little, but with good factors, should be
acceptable.'
BK> Also, speaking of sca, I recently heard about a new sca radio
BK> that I sent a message to Susan about. When I heard the radio on
BK> the newsreel, I didn't seem to perceive any crosstalk. How can
BK> this be?If anyone reading this heard that report, I'd
BK> appreciate your feedback. I'd suspect that it's possible that
BK> some sca's are made better than others, but, if you have any
BK> ideas on why this might be, please let me know.
You are right, some radios are better then others, and some stations are better
then others. All things being equal, there will be days where corsstalk is
minimul or not hearable in some locations. All the factors may have been right
for the newsreel demo.
David Andrews
... Your Sound Alternative
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