[aprssig] Dynamic weather beaconing

[scott at opentrac.org]

Roger, K1PNS, suggested this (or something like it) the other day and I
finally got a chance to implement it.

The OpenTracker in 1-wire weather mode now supports something a bit like
SmartBeaconing for weather.  Hopefully this will let weather stations run at
a slower beacon rate and still provide timely information about changing
conditions.

When enabled, the tracker will still transmit no more often than the
specified minimum interval.  Once that interval has been exceeded, it'll
transmit when the wind speed or direction changes by a specified amount.

The wind speed is averaged, and should be fairly insensitive to short gusts.
I may add a gust threshold test as well, if there's any interest.  Wind
direction change will trigger a transmission ONLY if the wind speed is above
the specified minimum.  This should help prevent false hits when the wind is
light and variable.

I think I might have mentioned it here already, but I've also added
consensus averaging (a la T-238) to the wind direction calculation.  It
seems to be significantly more accurate now.

The new firmware has been posted to the website.  You'll need the newest
version of the config program to see the new options.  Source code changes
have been committed to CVS.

BTW, anyone know what's up with aprsca.net?  Can't connect from my IGate.

Scott, N1VG
http://n1vg.net/opentracker