Friday, August 8, 2008

It's all greek to me... using digipeaters

So we're back in the swing of things and we are struggling to figure out how to make the GPS transmit in a safe way over digipeaters so that people who cannot come along on launch day can track us. Ideally the Micro-Trak will send out the coordinates, our callsign, and enough repeater parameters to not blast the world with our traffic, but maybe cover part of NC. If that works, then people can use to track the balloon on launch day! We could not get this working on Wed night so I called up Britt, our friend and "real" ham enthusiast for help. It turns out that the APRS powerpoint we were reading is old and crusty and that the WIDE and RELAY parameters are no longer in use. Instead there is WIDE N-n. While I'm still trying to understand what it all means, the gist of it is that larger N and n #s mean you spam the whole world with your traffic (a bad thing). It looks like the recommended parameters for a balloon or "mobile" is WIDE1-1,WIDE2-1.

APRS "Fixing Digipeaters" is a good reference. We'll keep checking to make sure that this is right but if the tinytrack sw and the APRS websites agree that's probably right. Would be good to get a better understanding of it for my own sake though. (and other future ballooners).

Some examples of how to use FINDU's map-near.cgi. It displays position reports known to be near a given location, which may be specified as a lat/lon, callsign, or zipcode.

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