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#21
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302 wind calculation
On Mar 29, 9:45*pm, Darryl Ramm wrote:
On Mar 29, 9:31*am, T8 wrote: On Mar 29, 11:29 am, Darryl Ramm *wrote: For the 180 degree wrong problem, any system that uses track and TAS/ GS difference calculations risks being 180 degrees wrong it it just has that difference on two reciprocal tracks. If you run straight down a ridge and do a rapid turn back the other way and fly the same track back the other way there are two perfectly equivalent trigonometric solutions which will give the wind from either direction. The flight computer has absolutely no idea what direction you are crabbing the glider into the wind. I understand the problem of very limited information. *This is a different problem :-). In this case picture wind from 360, trip out on ridge with track 270, 303 shows wind from 360 @ 12, relative wind 90 degrees, arrow points left (i.e. "wind blowing on glider" from right). *On the reverse trip, having failed to get a wind update, the computer now shows track 90, wind from 360 @ 12, relative wind 90 degrees, arrow points left. *See the issue? *Even in the absence of updated wind, the relative wind should be showing 270 based on old wind, new track. *I verified this behavior again yesterday, turning through 45 degrees (slowly), watching track change, seeing relative wind stay constant despite changing track until the device updated the wind. [edit: I managed to mung the tracks up the first time]. I have never noticed behavior like that. I'll look for that next time I play around. Seems like a simple firmware bug that maybe might be reproducible. Did Dave Ellis have any comments on this behavior? Darryl I described the behavior much as I have here. Dave was puzzled, but concluded that my 302 was not broken. I am able to reproduce this bug at will. *All* of the issues I see with the 302 have the look and feel of software problems. -T8 |
#22
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302 wind calculation
On Mar 30, 6:56*am, T8 wrote:
I am able to reproduce this bug at will. And here it is http://tinyurl.com/ygtwbvf Ridge on the left, correct wind showing in XCSoar in PDA (12 knots from 090 relative), 303 showing 4 kts from 333 relative. The wind calculation performance of XCSoar, using data from the 302, is absolutely outstanding. It's fast, it's accurate, it doesn't cough up garbage. The 302/303 is *buggy*. What's missing in all these schemes is a display of the age of the vector wind calculation on the main screen. -Evan Ludeman / T8 |
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