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[aprssig] Another kind of SmartBeaconing?

Scott Miller scott at opentrac.org
Tue Aug 21 22:00:47 UTC 2007


I considered adding some geofencing-based profile switching options to 
the OpenTracker, but so far I haven't gotten around to it.  I can 
probably manage it on the Tracker2.  It'd most likely take the form of a 
series of conditions (inside box, outside box, etc) that'd trigger 
configuration commands (e.g, INTERVAL 10).

The trackers don't need to be certified by the FAI, do they?  I know 
they have some requirements for loggers.  The hardware that ran the 
first OpenTracker (and its NMEA parsing code) were originally built as 
part of a paraglider datalogger project.

Scott
N1VG

Rikard Sohlberg wrote:
> 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
> 
>  Else
> 
> 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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> 
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