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External PDA wind not correct?

Posted: Fri Aug 28, 2020 10:44 pm
by mattm
Has anyone noticed that the external PDA does not report the same wind as the one on Condor? Today I was doing some wave flying, where the winds aloft were higher than at the ridge tops, but my external PDA reported the same wind all the time. To make sure it wasn't the external PDA (running TopHat) I checked the NMEA monitor, which showed me this:


If I remember my NMEA parsing, that "21.9" is the reported wind in km/hr, which computes to 11.8kts. TopHat is reporting 12kts of wind. The PDA in Condor is reporting 35kts at the same time.


Re: External PDA wind not correct?

Posted: Sat Aug 29, 2020 3:52 am
by Rotareneg
Yeah, I've noticed that too, I set XCSoar to use its own wind calculations because of that.

Re: External PDA wind not correct?

Posted: Sat Aug 29, 2020 10:39 am
by Bre901
If you take a closer look at the NMEAlog.txt, you notice that the windcourse and speed remain constant.

In the flightplan I set wind from 225°, 36km/h, in the NMEAlog.txt I get: 053,32.6

Apparently the "windcourse" is something like wind direction - 180°

Edited to add that wind speed and direction variation were set respectively to "low" and "medium"
I'll re-do some tests later

Re: External PDA wind not correct?

Posted: Sat Aug 29, 2020 3:05 pm
by Bre901
I did another test with no wind speed or direction variation

Flightplan.fpl :
WindDir=336.44775390625 -180 = 156
WindSpeed=5.08165550231934 =18.29395980834962‬ km/h

NMEALog.txt (same values in all the fixes)

This proves clearly that Condor sends the flightplan wind data, not the real-time ones.

Re: External PDA wind not correct?

Posted: Fri Sep 04, 2020 12:37 am
by mattm
My take on this is that it a hole in Condor function. I spent a lot of money on my RL vario so I could have one that would provide decent wind data to my flight computer.

So far TopHat seems to always believe that number, rather than compute it for itself. Maybe I'll go back to XCSoar, since it always seemed to prefer its own ideas on wind (even in the RL glider!).


Re: External PDA wind not correct?

Posted: Sun Jan 17, 2021 5:14 pm
by k6chris
Just discovered this bug too. The data that Condor passes to XCSoar as "external wind" is wrong, strength seems always to be about 60% too low. If you disable the "external" input in XCSoar's wind calcs, then it uses GPS drift, either circling or from two straight glides, and calculates it correctly. It's actually a useful thing to practice to see how quickly XCSoar can get wind strength and data the same as the Condor input (as shown on the Condor PDA).