Date: Fri, 01 Jun 2001 23:51:43 -0700

Author: Bernard Cleyet

Subject: Re: Range of 1000W FM station

Post:

In answer to a number of respondents -- John is probably applying for the new
class of low power community stations (non profit 10 or 100W)** in the "FM
Band" 88=> 108. The capitalist (corporate) NAB with the assistance of the NPR
lackey managed to reduce the number offered to about 10% of the FCC's initial
proposal.

Strictly line of sight is an exaggeration due to tropospheric scatter and
terrain diffraction. The scatter requires very sensitive receivers and
special detection if there are competing signals. Diffraction is often
important at distances ~/> 100 miles. I receive well a stn. 100 mi. distant
nearly every day -- I'm in a valley. The exception occurs in the Spring and
Fall due, I believe, to the weather -- probably a temperature inversion in the
Santa Clara Valley. When that happens I still receive, with a varying amount
of interference from an adjacent channel, "my" stn. Before the FCC granted
that local station a license (obviously to interfere with reception of the
radical, anti-capitalist stn.), reception was continuous, just occasionally
weak.

"My" stn has an ERP of 59 kW. I guess (the engineer was out when I called)
the input to the antenna (from the final amplifier -- the exciter power is
irrelevant here) is 10 kW. This results in an antenna gain of ~ eight dB.
The stn. has no interest in serving as a source for Martian SETI's or ships at
sea. I think ED has conflated two kinds of noise first the shot noise in the
first stage which is masked by a strong signal. The AGC (auto. gain control)
prevents overloading. Second impulse noise (ignition lightening, etc.) which
is clipped by the limiter. More modern detectors (than the original ratio
detector) inherently perform the limiting.

About hearing two stns. simultaneously -- i experience this always as I drive
to and from the SF Bay area. I tolerate it much longer if "my" stn. is
broadcasting music.

bc

**Obviously I'm wrong as JH wrote 1 kW.


"John L. Hubisz" wrote:

> Would any of you folks have a rough idea of the range of a 1000W FM
> station? The FCC is calling for applications for such stations and their
> deadline is June 11th and I wonder if this would be feasible in my area.
>
> Thanks,
>
> John
>
> John L. Hubisz, Physics Department, Box 8202, North Carolina State
> University, Raleigh NC 27695-8202; hubisz@unity.ncsu.edu, (919)515-2515,
> (919)515-7331 FAX
>
> HOME: 1604 South Salem Street, Apex NC 27502-7251, hubisz@mindspring.com,
> (919)362-5782 (Voice & FAX)

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