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ATTI mode and altitude

Discussion in 'Pro/Adv Discussion' started by FredzMaxxUAV, Jul 28, 2015.

  1. FredzMaxxUAV

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    How does the ATTI mode on the P3 actually, technically, work? If I take off at an altitude of 0 (of course) from a hill, and I then go lower, is there a way to use ATTI mode to warn me when I am almost at ground level (which could be -10 for example)? I like to fly low to the ground, but on the display it's hard to see if you are too low. With ATTI mode, can the P3 somehow measure the distance to the ground with the VPS? Or will it still display the altitude as in GPS mode using minus?
     
  2. Meta4

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    The GPS has nothing to do with altitude.
    The Phantom uses a barometric altimeter for altitude in all modes.
    The VPS is only useful under certain conditions - (see the P3 specs for details) and only for 2-3 metres.
    Atti mode is not going to do anything extra for you beyond what you would get in GPS mode but you would not have the benefits of GPS position holding.
     
  3. msinger

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    If you have VPS enabled, it will show you an estimated altitude if flying at altitudes of 0.3 to 3 meters. The Phantom manual mentions a long list of items that can cause an inaccurate reading -- that's I'm using the word "estimated". VPS will not warn you if you're about to crash though. It would be better to make sure you stay in visual contact with your Phantom at all times and adjust the altitude as needed.
     
  4. FredzMaxxUAV

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    So in ATTI mode, altitudes above 3 meter aren't displayed?
     
  5. sergekouper

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    VPS kicks in whe you have lost GPS signal. It is supposed tomaintain your position if you are at less than 10feet from the ground, which makes it great for flying inside. Other than that, nothing else AKAIK.
    I 'm not sure I get the question right, but I guess the barometric gives you your height at ground level when taking off and keep this value as long as your flying. so if you loose GPS and have to rely on VPS for some reason, that could be a problem. Not sure.
     
    #5 sergekouper, Jul 28, 2015
    Last edited: Jul 28, 2015
  6. Meta4

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    Your altitude comes from the barometric altimeter.
    It doesn't matter whether you are in GPS or Atti mode - it's all the same.
     
  7. msinger

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    The VPS distance and altitude are two separate values in the DJI Pilot app. When flying over 3 meters, the VPS value should not be trusted. When flying below 3 meters, the VPS value might be more accurate than the altitude -- depending on whether or not you're flying in any of the situations mentioned in the Phantom manual (e.g. over water or over highly reflective surfaces).

    Keep in mind that VPS works best when flying indoors.
     
  8. Meta4

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    To go back to your initial question...
    Here's the section of the manual that explains ...
    [​IMG]
     
  9. FredzMaxxUAV

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    Did some ATTI flying. The P3 flies about 2-3 meters/second faster than in GPS mode (when there is no wind). I can get up to about 17 or 18 meters/second without wind or subtracting the wind speed.