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Altitude showing incorrect

Discussion in 'Phantom 2 Vision + Discussion' started by tedw123, Apr 18, 2014.

  1. tedw123

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    My new Vision+ shows -42 feet when it is on ground? I've tried turning everything off and on but no fix. Anyone else experience this or know how to correct?
     
  2. BlackTracer

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    If you are flying in Death Valley, then that would be correct. J/K. Sounds like a GPS problem.

    I would try reloading all the firmware first through the assistant. I think you can force firmware updates even if it is already up to date. Then do an advanced IMU calibration, stick calibration, compass calibration and see where that gets you. That's the least I would do before sending it back.
    Can also call DJI support and see what their recommendation is, but good luck with getting through.
     
  3. MikesTooLz

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    the altitude is how high you are from sea level not the ground.

    download a GPS app on your smartphone and compare the phones altitude with the phantom.
     
  4. Dirty Bird

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    Is your location actually below sea level? GPS is not as accurate vertically as it is in the other two axis. Vertical accuracy is much more dependent on satellite geometry. Even if your GPS is incorrectly reading your altitude, as long as it is consistent it should not matter. When it home locks at -41', it will just think the ground is at that -41' point and measure everything else accordingly.
     
  5. tedw123

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    Thanks, my Phantom 2 Vision was always around zero when on the ground though.
     
  6. tedw123

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    I'm in Oklahoma and my old Vision always was around zero when I was on ground. Dealer suggested advanced IMU calibration, I didn't know that would correct altitude but worth a try I guess.
     
  7. MikesTooLz

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    Could be # of satellites available
     
  8. tedw123

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    Thanks. I had a Vision before and never had issues but I even noticed on a fast ascent on take off the gimbal/camera shakes a bit. I don't really think anything is wrong but possibly the 4 rubber vibration absorbers a bit soft for this gimbal/camera on Vision+ compared to the Vision white plastic one. Possibly the wash from full throttle on props? It's not really noticeable in video but visible to me. Have you ever noticed this? I'm just curious as if there is an issue don't want to miss my 30 day window.
     
  9. Hawk Eye

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    Ted I live 4,200 ft. above sea level. My altitude on my P2V or my P2V+ has never displayed my "actual" altitude. That would be useless information to me. As the terrain varies, I would constantly have to memorize my new Zero Reference point (Ground Level). If my bird was out of site and didn't remember what the "altitude" was when I took off, I would have no way to know how far I was from the ground. Therefore, I believe take-off should be around 0 feet +/- the GPS height tolerance or accuracy which I believe is around 5 feet. Therefore, I might be concerned about -42 feet. By the way mine was showing -16 feet at take off with 7 GPS sat's locked on. 7 is usually enough for me to get to zero +/- 5' but not today. I am concerned enough that I will be keeping an eye on it. Especially since it almost crashed from lack of stability on decent upon the "return home" mode at 800' from the ground, about an hour ago (night flight). >
     
  10. srandall25

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    Mine lost total stability twice today... and landed hard... very erratic and descended on its own... may i ask for the details on your 'lack of stability on descent'? Just curious as i'm still trying to troubleshoot mine... Also, on my return to home today, it came down very fast and landed so hard it bounced back up and down again... Could this have been because it thought it had x more feet until it hit the ground when it really didn't?
     
  11. Hawk Eye

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    I just posted this on the Naza thread because of similar situations. "RETURN HOME ALERT! 2 hours ago I was testing a night-flight with my PV2+ in "Phantom Mode". This was I believe my 7th flight since getting it on Tuesday. I had 7 GPS locks and position confirmation prior to take-off and after 10 minutes I was flying 1000' directly above my home and "Lost Control Signal". No big deal it happens all the time right? My screen then said "return home" (all normal still), then I lost telemetry for at least 5 seconds (Common on my "old" P2V) and when it came back it was at 800' and my bird was severely oscillating back and forth like a cat was smacking it between its paws from behind. The 3 axis gimbal did not have a fighting chance against the unstable flying (Yes I have Video - Night time). I calmly moved the right switch S1 to the middle position, to take control of the "attitude of my bird", and then my P2V+ was in denial, as if it never happened and flew fine after taking control. By the way the oscillating was very audible at 800 ft. and the even my wife had to chime in with "What is wrong with that thing? Sounds like it's going to crash"? Despite her helpful comments and shaking the fresh crap out of my pants, I was able to avoid panic. I literally thought it was going to crash into house straight down from 800'. By the way, the return home function has activated at least 3 times prior to tonight without any trouble at all. By the way there are no birds or bats in this area that fly at night at 800' in complete darkness that I am aware of or show up in the video."
     
  12. tedw123

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    I am going to try an advanced IMU to see if it helps at all. Today it showed -120 feet before takeoff!

    Sent from my SPH-L720 using Tapatalk
     
  13. AmosMoses

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    I actually had this problem today. The app was showing 42' sitting on my deck. I just shut everything off and power cycled it all back on. Fixed it!

    Sent from my SM-P900 using Tapatalk
     
  14. tedw123

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    Although software indicated I didn't need to do IMU calibration I did. I did Basic first and it did nothing. I did Advanced, it did nothing to correct altitude reading. My Vision was always on within 1 or 2 feet. Every time I turn my new Vision+ on, the altitude might read -42 feet, the next time -123 feet. I guess I will have the fun of calling DJI and/or dealer tomorrow. Any other suggestions?
     
  15. Flyer91

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    The reading for the altimeter is only for information, and does not impact flying at all.
    It's zeroed at startup, and provides a very accurate/sensitive barometric pressure signal that's converted to feet/meters.
    If working properly at start-up it should read close to zero, irrespective of what altitude you are actually at, and doesn't require any GPS lock.
    You can verify this by doing a test start-up on the bottom floor of your home, and again on the second floor or whatever.
    Both will say close to zero at startup .... and with no GPS lock at all.
    Unfortunately it can nt be calibrated, and is either working properly or needs to be replaced.

    For flying .... the Vision uses GPS to determine where it is.
    That includes lat/long and 'actual' altitude.
    It doesn't use the barometric reading for this, only the signal from the GPS sats.

    If it's not within a few feet of zero I'd return it for one that is.

    Of the 3 P2Vs I had, two were within a few feet at start-up , and would fluctuate between apx +/- 3' or so, and one was like +/- 60' ... which was the reason I returned it.
    All of them would RTH properly .... even the one that showed as low as -60'.
     
  16. tedw123

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    Actually, went outside after Advanced IMU and didn't know if necessary to do the compass calibration, so attempted and it failed repeatedly. I then plugged back in and it said needs Advance IMU, so I ran again and down to 18 feet. I let the advanced IMU run for over 15 minutes initially, the green bar was gone but just realized the second time that tiny green check mark, so maybe wasn't finished first time, who knows. You think DJI would have a notification when calibration is complete, I guess that would make to much sense!! I guess the little green check mark means finished?

    I didn't have to do a thing to my first Vision, hope my new Vision+ isn't a lemon.
     
  17. srandall25

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    I hear ya buddy! My thoughts exactly! That combined with the "Over heat" message... it gets a little confusing when determining if the calibration actually started because you see a progress bar... if it's ok to turn power off in the middle of the calibration (if it is calibrating) because it's give you the prompt to restart since it's too hot... or if the calibration is complete and successful... This needs to be polished up a bit...
     
  18. tedw123

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    What are you supposed to do when you get that "Temperature of MC is too high" message, ignore it or click the "Yes" button?
     
  19. AmosMoses

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    Yes just ignore it. It happens to everyone every time. It's just a glitch.

    Sent from my SM-P900 using Tapatalk
     
  20. Mori55

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    Flew my new + today and my attitude was about 40' off. Distance was good. And just about at sea level. Any ideas?