[aprssig] Another kind of SmartBeaconing?

Joel Kandel kandelj at bellsouth.net
Wed Aug 22 09:10:02 CDT 2007

And miss all the fun when the Hubble mirror is out of focus? Never
  ----- Original Message ----- 
  From: Rikard Sohlberg 
  To: aprssig at lists.tapr.org 
  Cc: 'Mikael Engström' 
  Sent: Tuesday, August 21, 2007 5:50 PM
  Subject: [aprssig] Another kind of SmartBeaconing?

  I would like to throw out a question. 

  I use APRS for tracking gliders (sailplanes). From humble beginnings here in Sweden, it has grown into a big success, almost turning a niche sport/event into a spectator sport. Watching a sport where the track is anywhere from 150 to 500 km (when will you boys go metric. ;.) used to be a problem. Now we have some 25 trackers active in Swedish gliders, and everybody loves it. And, yes, it is perfectly legal, even when there is no ham onboard. Of course I can't speak for all jurisdictions, but at least in Sweden, we are OK.


  Now to my problem or question. We have tried SmartBeaconing and fixed interval beacons. Neither one serves a glider particularly well. A glider (when it leaves to vicinity of the airfield), typically circles in a thermal to gain altitude and then flies in a straight line to get around the track. Tests of SmartBeaconing has shown that it is not well suited to this kind of motion. In fact, it gives the exact opposite of what we want, se below. Also, to have an exact fix when the glider is 200 km away is not needed. What is needed, though is fast updating at the end of the track. Incredible as it may seem, many competitions end up with the gliders chasing each other within a few meters (ehh. feet any one.;-) apart in the race to the finish line. And that is often the case after flying a track of, say 300 km and 3-4 hours. Speeds are typically up to 250 km/h (mph..?) at the race for the finish line.


  So after this wordy preamble. What I see needed is some kind of Geofence/box-type beaconing. 

  The algorithm being something like:


  If (tracker.lat<N60.5 and tracker.lat >59.8 and tracker.long<E16.5 and tracker.long>15.9) then beacon every 10 secs

  If (tracker.distance-to-goal-line < 5 km) beacon every 2 secs


  Beacon every 3 minutes


  I'm not a programmer (any more), but you are clever guys, you get my idea. When inside the box (including the starting gate and finish line) beacon often, outside the box fall back to once every 3 min or so not to clutter up the QRG. 


  Does anyone know of some tracker code/application for this?


  Of course, what would also be handy would be a Glider specific mode:


  If(course .changes. more than 15 seconds) stop beaconing    ./ When entering a thermal and starting to circle /.

  When (course .eq. last.course(15 sec))) beacon                    ./ When leaving the thermal and flying in a straight line  /.


  Any one out there doing something like this? 


  Thanks for any thoughts and ideas.


  73 de SM0JWX/Rikard


  (Go metric before Burma, please.)










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