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Won't increase altitude on rth

Discussion in 'Phantom 2 Discussion' started by AlTiTuDe06, Feb 7, 2014.

  1. AlTiTuDe06

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    Question for you guys...just got phantom 2 A couple of days ago. I was playing around with the failsafe and noticed that I if I'm low to the ground The Phantom will not rise to 20m .... It will return to its home position but will not rise.... If I engage failsafe when I'm higher than 20 m it will return to home position as well....thanks in advance
     
  2. AlTiTuDe06

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  3. LeoS

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    Phantom version?
    Firmware version?
     
  4. AlTiTuDe06

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    Firmware 1.08 and it a p2 NON vision
     
  5. AlTiTuDe06

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    posted this question on another forum as well.... a member suggested that it might be he internal barometric sensor....... my mini osd will be in this week.... does the iosd read altitude off of the gps or the barometric sensor?? if it reads off the sensor it would tell me if the sensor was working properly or not... if it reads off of the gps than i dont know what else to do... i have also fwded this to dji support to see what they have to offer....
     
  6. AlTiTuDe06

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    Just bumping in case anyone else has encountered this issue.....
     
  7. QYV

    QYV

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    Wish I could help... I voluntarily utilize the failsafe feature all the time to let my P2 autopilot back overhead for me, and in all my testing when below 20m it indeed ascended before it started moving laterally.
     
  8. AlTiTuDe06

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    Has to have something to do with the barometric sensor.... Iosd altitude readings are not always correct... Sometimes at ground level the readings are -12m or 12m etc...... Altitude is determined by the naza unit correct?
     
  9. QYV

    QYV

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    I'm afraid I'm a little confused why you're saying "barometric sensor" or barometer. a barometer is for measuring atmospheric pressure, I'm not sure how that would relate to a Phantom knowing it's altitude. as far as I know, the phantom determines it's altitude with GPS just like it's other positions. GPS is actually a 3 dimensional measurement, not just two. When you power on the Phantom and it home-locks, it registers whatever GPS "height" it's at as ground level and I believe that should be where it bases failsafe at... ground + 20m

    Are you letting the Phantom properly do a GPS-lock (rapid blinking green lights) before takeoff? Have you checked in the Phantom Assistant software if the IMU needs calibrating? Have you done the "spin around" compass calibration procedure? If you don't know what any / all of those are I'd be happy to elaborate
     
  10. AlTiTuDe06

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    I was under the impression that the phantom determines the altitude by a combination if atmospheric pressure... (Barometer) AND the gps signal.....correct me if I am wrong..... If altitude was determined solely by the gps when switched into atti mode wouldn't the phantom fall from the sky??




    And yes I have calibrated imu plenty of times and I am fully aware of waiting for gps sat lock...
     
  11. N017RW

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    There is a direct, inverse, relationship to atmospheric or barometric pressure and altitude.
    (Just like diving under water.)

    It may not know it's altitude form this sensor alone without compensation for ambient changes, but it will know if the altitude has changed.
     
  12. Big Ben

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    An altimeter as used in planes IS a barometer, just with a different scale in meters or feet instead of atmospheric pressure. Pressure decreases with height and that's why measuring the pressure is a good way to measure altitude.

    A GPS receiver is far less accurate at measuring vertical position than it is at measuring horizontal position. The Phantom will therefore most likely not use the GPS data for determining its altitude but only its barometric pressure sensor, which is an altimeter.

    The Phantom NOT rising to the 20m failsafe altitude would make me suspect the pressure sensor too.
     
  13. QYV

    QYV

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    indeed yes I understand that a change in barometic pressure can be used to determine a change in altitude, but at a fixed altitude say ground level barometric pressure also changes with the weather so I couldn't imagine that a sophisticated piece of equipment like a Phantom with a multi-satellite GPS lock would RELY ONLY on that as knowing when it changed altitude :)

    I try to be helpful around here but I certainly don't know everything. I didn't realize there was even a barometer in the Phantom I figured it used a combination of GPS + accelerometer but I did some googling and turns out yup it uses GPS + barometer so indeed that could be OP's problem... a bunch of my google results were people mentioning height issues with possible bad barometers so.. yea. if it's a brand new Phantom that might be a case to take it to your vendor for exchange/repair
     
  14. riblit

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    If the barometric pressure is read and stored by the Phantom FC at takeoff it can compare it with the current pressure reading and calculate the height above ground while flying. Given that a flight is less than 25 mins and within a mile of so of the takeoff location, unless there is a dramatic pressure change the craft will have a good idea of its height. If there is a dramatic pressure change the accompanying wind, dark clouds and rain should be enough to convince the pilot to land and repair to a drier environment.
     
  15. ianwood

    ianwood Taco Wrangler
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    Based on data taken from the CAN bus, I can confirm the Naza uses the barometric sensor to measure altitude. The GPS altitude is not used for anything as it is wildly inaccurate below 10 satellites.
     
  16. AlTiTuDe06

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    Looks like ill be replacing the naza..... It's not really big issue it's more of an annoyance than anything as unusually fly higher that 20m anyway ... But it sure would be nice to have an accurate altitude reading at all times...
     
  17. Big Ben

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    If it never worked properly you should simply claim warranty and let DJI fix it for you.