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Kalama South Propagation Test

posted Mar 8, 2021, 6:22 PM by Charles Boling   [ updated Mar 8, 2021, 6:31 PM ]
As Masen, KF7HVM reported, in January we did a little VHF/UHF propagation testing in the south part of the Kalama area for the Kalama Ward.  Each team worked a maximum of 3 locations, but we tested over 1,200 RF paths altogether, with the plan being for every location during each of the 3 time periods being listened for by all of the other stations, using each of these 6 modes:
  • M = 2m Ham Mobile (50W)
  • H = 2m Ham Handheld (5W)
  • F = Family Radio Service handheld (0.5W)
  • G = General Mobile Radio Service mobile (50W)
  • C / Citizens Band (4W) - note handheld/mobile
That list was pared slightly by these restrictions:
  • Due to lack of gear (and because the exercise was already complex enough), we dropped CB entirely from this round
  • Only 2 of us had GMRS the whole time
  • One team had only FRS
  • One team lost their mobile partway through the exercise
In the 2.5 weeks after the exercise I interpreted & entered data from the log sheets, geocoded the addresses, and prepared summary and detail reports along with a map showing the test sites.

I also wanted to use the data to automatically plot the signal reports on the map, but after looking at what it would take and realizing that I didn't really have time or desire to become a javascript & Google API expert right now (though such a propagation visualization tool would be quite valuable for many such exercises), I put it off.

Now, a little over a month later, I manually plotted lines on the map to illustrate the propagation in a way that's much easier and faster to see overall than the tables. The result is the PDF available below.  I gave the Kalama Ward EmComm specialist 4 additional maps, one showing just the FRS/HT coverage and 3 that split the area by site location to reduce the clutter of lines a bit. (His copy also had names of families living in the homes near our test sites.)

A couple of other ways I reduced clutter on the map:

  • I didn't bother to plot any "poor" connections -- only the paths proven good enough for a reliable conversation.
  • For any path that was able to be used by handheld, I did not show the mobile ham paths.

Not surprisingly, we didn't have very many successful contacts using FRS, though there were a couple of fairly long line-of-sight paths.  I was somewhat surprised that the 2m HTs didn't outperform FRS by a greater margin. I expect that one reason for this is that the testing was done inside vehicles (a/k/a Faraday cages with holes) and the longer wavelength would've been attenuated more (i.e. it's harder to stuff a 200cm wave through a car window than a 65cm wave). It would've been interesting to test outside vehicles, but, again, the exercise was long and complex enough as it was.

I was the only station that didn't move during the exercise; once we left the elementary school where be briefed, I headed up the hill to a spot with a little better view, even though it was outside of the area that our testing was focused on. Since I was directing the exercise, I didn't want that extra distraction, and I did want to be able to talk to everyone directly if possible. I nearly achieved this; I think that there was only one distant site worked by a mobile unit that I didn't log a contact with.

I've never had to do mapping on a test with this many data points. It was a lot of work! 'Twas an informative exercise, though, for all involved, not just the recipient of the results.

Future tests will cover central Kalama and the area north, including the Kalama River and Rose Valley.

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Charles Boling,
Mar 8, 2021, 6:22 PM
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