Radio range testing

Posted by JonM on 12 April 2008

Dan and I went out today to do some radio range testing. We decided to start small and stay within Seattle city limits. We had two sets of sites, the first about four miles, from Magnolia Park to Alki Beach Park. I went up to Magnolia Park and set up a nice little testing station:

Test station at Alki

First and foremost was testing the Digi XTend RF modem, which will be our primary data link from the ground station to the payloads. Dan set one up on the Alki beach running medium power, and they immediately paired with a nice, strong, signal. Depending on the antenna orientation, we got from -62 dBm down to -74 dBm, which matches our calculations nicely. Further testing will be needed to verify the path fade, but I'm pretty sure we'll be able to get up to 100 miles of range with no problems.

The surprise star of the day was the BeeLine homing beacon. That little green guy was heard 4 miles away:

Pretty impressive for a self contained package that weighs less than half an ounce and
will run for 48 hours on a single charge!

After that success, we decamped and headed over to the second pair of test sites. I set up at the out of service boat ramp at Sand Point:

I got the call from Dan that we was set up and...nothing. It turns out that Dan had misinterpreted the south site (a boat ramp near Seward Park), and had setup in Seward Park proper. Our clear 8 mile line of site was now a clear 6 miles with 2 miles of Mercer Island in between. Ah well, at least the weather was nice.


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