Reading the Sonar works for your altitude for <10 feet right?  After that the baro takes over.  

In the APM I see that when I lift the quad over my head I still read like 1m or 0m.  Any thoughts on that?



In CLI mode it reads like 20cm to 80cm... However its noticeably off.  Do I need to calibrate this thing?  This is the LAST thing I need working before we get into missions.  I am so stoked!



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I read your other thread more closely and I have a better idea of what your seeing. I think though that the MB1200 is the recommended sensor for most users and I can see needing scaling of some sort particularly for other sensors that are scaled differently. I flew an MB1260 scaled and unscaled on my quad with Jason's earlier code and it seemed to work pretty well.  I had  "fly aways" early on and it was due to noise spikes jumping from 500cms (actual) to 90 (bad) cms for many samples when the reality was nothing close to that. Motor noise was definitely causing my fly aways. I think your I2C approach is the ultimate solution  to the noise issues and that calibration will be needed for some cases (such as I.S. optical flow comment or using different sensors), but not by most general users if they're in standard configuration. It's just confusing trying to get the sonars to work and scaling by an arbitrary scaling factor is expensive computationally (fixed point multiply) unless your scaling in powers of 2.

Seeing a log of sonar alt, baro alt on  "fly aways" that don't have noisy sonar data would be very interesting.





An other problem is wat I suspect to be the built in error correction in the mb1200. Pls fly for about 15mins with alt-hold on on your quad lets say 20m away and back. and so on and so on. Then after about 15min the sonar will be completely off and will only output the default 32cm and nothing else. My suspision is that after to many error the sonar just shuts down. After waiting for about one hour. The sonar will work again. I think this has to do with the complete discharge of the entre quad.

Hi Dany, what's your ratio wirh MB1200? I've found "0.80", good value on my system...

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