RadioBanter - View Single Post

November 20th 03, 06:16 AM

(John) writes:

1) How can AM be made more one directional than another?

The usual method is to put up two or more towers approximately
1/4 wavelength tall and vary the phase and amplitude of the signal
fed to each to produce the desired directional pattern.

2) How far can an STL wireless transmission reliably broadcast?

Up to about 40 miles depending on the height of the antennas, their
gain, and the power used. The terrain must be favorable.

3) How far could a big FM signal reach, assuming little constraint on
power?

The reach will depend on the antenna height and the surrounding
terrain. A California FM where I used to work ran 18,500 watts from
the top of a 3,000-foot mountain and had regular listeners 100 miles
away.

4) In FM repeater networks, how many links down a chain can a signal
reliably be put through? Are repeaters normally only a one stage
phenomenon, used like spokes in a wheel, or can you set up a chain up
and down a long valley for example?

I don't do repeaters, but there used to be a network of public radio
stations in New England that relayed "Morning Pro Musica" from one
station to another. The farthest station was 3 or 4 stations down
the chain and sounded pretty grungy, according to what I was told.
But this was 20 years agio, and technology has come a ways since.

5) Does anyone know about renting space on satellites?

Yes; we're doing that right now.

How much it
would cost to have a 24 hour audio channel beaming down to receivers?

We're paying $2,200 a month to lease channel space on Galaxy 4R from
National Public Radio. We use the channel 24 hours a day to feed
a dozen or so affiliates from Maine to California.

How much a single uplink mechanism might cost, and receiver dishes?

The uplink cost us about $50,000 to set up. The receive dish I set up
at one affiliate cost about $10,000, including the dish, the receiver,
and installation.

But of course we're not in Afghanistan.

umar
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