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Won't get full satellite lock (just 6)

Discussion in 'Phantom 2 Discussion' started by icordoba, May 26, 2014.

  1. icordoba

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    Hello,
    I'm having a problem when flying my Phantom 2. It hardly gets full satellite signal (more than 6 sats -> no red flashes). It stays a very long time with 2 red flashes (5 sats) then goes to one flash (6 satellites) and that's the best I can get. (Of course, with the corresponding green light, 2 green flashes if I move any sticks (control not at center).
    Is it normal? I am testing in my garden with some trees and about 20m from my 2 story house, I guess clear enough to get full satellite lock there. Also, i have had a couple of small crashes (just bad landings) but nothing important. I didn't even have to replace any prop or anything.

    I ask here because I was getting full satellite signal before my last firmware upgrade. May be it's just a matter of going to a full clear field. Thanks for any advice.

    Ignacio @ Madrid
     
  2. ianwood

    ianwood Taco Wrangler
    Staff Member

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    Some people have cracked their GPS antennas as result of crashes but more likely than not you would be getting even worse performance if that was the case.

    The Phantom GPS seems to be very picky about locking satellites. In an open space, with mostly uninterrupted view of the sky, it's not uncommon to get 9 or 10 satellites before take off and then 12 to 14 in the air. But in areas with limited obstructions that performance goes downhill very quickly. For example, with a tall building on one side and mostly open in all others, my phone can lock 10 satellites in about 20 seconds. The Phantom sits there with 5 for an eternity before it gets the 6th consistently. And then in the air, it will drop to 4 and go up to 9 briefly and back and forth.

    Each time the Phantom gains or loses a satellite lock, it will experience a "GPS jump" where the location fix jumps to a different location. The lower the number of satellites, the bigger the jump. The jump can manifest itself in the Phantom moving on its own and/or it thinking the home location is somewhere very different than where it actually is.

    Either the receiver is not the most sensitive or the built-in saw filter is very sensitive to distortions caused by trees, building reflections and what not. Your only option is to find a better spot with more clear access to the sky.
     
  3. ladykate

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    Just go to a clear field. I get 5 in my front yard. On FPV, when I get up about 30 feet, I have 9 or more. GPS reception around buildings, trees or other obstacles can vary wildly.
     
  4. icordoba

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    Thanks both for your replies. I've also tested other GPSs in the same location and get more satellites recognised (and faster). I cannot understand how DJI does not solve this in a product where GPS reception is so critical. I'll test it in fully open space to be sure it's not an antenna problem.

    BTW, anybody nows any custom improvements to satellite module or antenna that might improve this?

    Regards,
    Ignacio @ Madrid