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Old March 7th 12, 04:14 AM posted to alt.internet.wireless,rec.radio.amateur.antenna
miso miso is offline
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First recorded activity by RadioBanter: Oct 2011
Posts: 7
Default What's the most accurate elevation tool on the net (freebie)


Oops. I meant the SRTM1 maps.
http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/

I've used Radio Mobile and SPLAT!. I never got a warm and fuzzy with
Radio Mobile. Of course, it is a bit more complicated to use SPLAT!.


I've used both. Radio-Mobile has a very steep learning curve.
Important functions are buried deep into obscure menus, useless trivia
is scattered all over the menus, there's no logical sequence of
operation, and many of the terms require expertise in cartography.
Debugging errors is tricky as important items, such as the performance
characteristics of the radios, are scattered over a half dozen menu
pages. I find myself constantly referring to my cheat sheet in order
to get anything done. However, I haven't found anything else that
even comes close to what it does.

One obvious advantage to SPLAT! is it can analyze very large areas. Not
all that useful in the case of this wifi setup, but very useful in sigint.


http://www.qsl.net/kd2bd/splat.html
Splat is somewhat easier to use, but as you note, is designed to
display repeater coverage. It's less useful for close in coverage, or
showing coverage details, as in mountainous or urban jungle terrain.

Both programs put considerable effort into implementing complex
terrain models. For 2.4 and 5.7Ghz, optical line of sight is close
enough.


My recollection of Radio Mobile is you need to crank down the minimum
angle that it sweeps to get any accuracy. Like I said, I prefer SPLAT!
for the accuracy. Even so, it is only as good as the NED. However, if
SPLAT! says you can see it, then you can see it. I thought Radio Mobile
was simple to run, at least for one transmitter at a time. Far easier
than SPLAT, which requires compilation parameters to set the array size.
Radio Mobile, at least when I read it, was stuck at 3600x3600. If you
exceed that array, and note it uses a 1/3 arc second grid, the program
interpolates.

The grid is 10 meters on a size for 1/3 arc second. That means you can't
"see" more than 36km. Plenty for wifi, not so good for repeaters or even
photography.

I generally do two runs with SPLAT. First I check the altitude when the
radio is to be located. If it doesn't match the topo map, I add the
difference in altitude to the transmitter height. Then run it again.

I have a 90 mile path to analyze, so I guess I'll see what these
programs can do lately. But if Radio Mobile is stuck at 3600 pixels,
that is a show stopper.