"Senor Couchwarmer" wrote in message
...
I have been doing some FM DXing lately, and have been trying to come
up with some "number" to give a relative value to what I have heard.
I know that I cannot look at just transmitter power and distance,
because the transmitter's HAAT has a definite bearing (pardon the
pun...not a reference to a directional antenna). Do any of you know
of a website (or anything else) that can clearly specify the
important
criteria for this kind of evaluation, and maybe supply equations as
well?

I have studied the FCC "FM Curves" and other information they have
posted, and the closest thing I can find is a page that specifies
the
maximum ERP for a station given the class of a station and the
antenna
HAAT. I don't honestly know if anything that I can derive from that
would be directly applicable to what I'm trying to do. I also may
have my head firmly lodged somewhere thinking that this can be done
too. Advice and suggestions gladly accepted.

Are you trying to evaluate how far beyond their normal coverage you
are hearing a station? If so, the FCC has a contour plot for every FM
station on their FM Query. The plot is for the 1 mV/m contour for all
stations except Class B, where it is the 500 uV/m contour. These are
the protected contours. These field strengths are those predicted for
a receiving antenna 30 ft above ground. Coverage depends very strongly
on terrain.

Doug Vernier's Am Fm by ZIP Code web site
http://www.v-soft.com/ZipSignal/zip_answer.asp
gives predicted field strength for every ZIP code down to signals well
outside their protected contour. He's in the coverage prediction
business so I'd trust his data. Of course it is meaningless within
the same ZIP code as the transmitter.