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Weaker GPS Receiver on PV vs. Phantom 1?

Discussion in 'Phantom 2 Vision Discussion' started by billkoep, Dec 12, 2013.

  1. billkoep

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    I have recently upgraded to the PV after having a version 1 for almost a year. During the past year I have flown the P1 many times in my back yard with no trouble receiving GPS signals sufficient to maintain constant green LED indication. Now, in the same locale, the PV will slip in and out of GPS mode -- changing to flashing yellow from flashing green -- with flight characteristics expected of ATTI (or non-GPS) flight. Even hovering in one spot this can happen. It comes and goes, and is indicated on my iPhone as GPS has insufficient number of satellites (I think -- it's too small for me to easily read in outdoor light).

    My yard does have numerous tall pine trees all around, and when I go to a nearby park with more open sky the GPS mode on the PV is entirely stable. Also, if I fly high enough to clear those trees, the GPS becomes more reliable with height. So, is there any plausible explanation of why the GPS receiver on the PV might be weaker than the one in the P1? Can anything be done to improve GPS reception on the craft?

    I live in heavily wooded country. Anything I could do to improve GPS reception around trees would be a great help.
     
  2. kenskid

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    You've already did the "scientific" study. By going to another location and/or flying higher than the trees, you have shown that your new Phantom GPS receiver is somehow "weaker" than your old one. I guess the only thing left to do would be to swap each gps antenna into the other phantom and see if you see the same results....only in the "other" Phantom. If the "other" Phantom now shows weak GPS then you know it is the antenna...etc...etc...



     
  3. billkoep

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    Thanks, kenskid...

    I sold the older one prior to buying the new one, so I can' try your experiment -- but that's a good suggestion. In my post I was hoping to find out if anyone else had encountered anything similar. Because the behavior is so noticeably different I am just wondering if I have a slightly defective GPS receiver -- or maybe there is something internally wrong with the way it is installed. I have a hand-held GPS and GPS in two cars, and none of those have trouble getting signal in my neighborhood. Since the P1 got good satellite coverage, it just seems strange that the PV is having difficulties in exactly the same circumstances.

    Since the system does work, I doubt I'll have much luck trying to get a warranty replacement. My next best solution would be to replace the GPS. If anyone knows if it's possible (and reasonable) to buy and install a replacement GPS unit for the PV, I would appreciate some advice. Thanks!
     
  4. Pull_Up

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    Location:
    South Oxfordshire, UK
    I haven't tried replacing it, but in my "how to open" video at http://youtu.be/FLgwyoJvqM8 you can see the GPS module is stuck to the underside of the upper shell underneath all the shielding material - there are two wires coming out, one is the compass and one plugs to the main board. The implication is that it would be relatively straightforward to replace, but without peeling all the shielding off to have a good luck who knows what's under there?!

    I have seen a European dealer offering spare Vision GPS modules at around 139 euro, but not showing in stock. I suspect you'd have to order one specifically from a dealer, as at this stage I don't think many are going to carry large stocks of anything except batteries and props until they get a feel for what we are managing to break on our Visions!
     
  5. billkoep

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    Thanks, Pull_Up... Your video is a big help. I will at least open my PV to have a look and see if there is anything that looks out of place. I'm sure you are correct that spares will be a while in coming for anything other than the basic breakables and batteries. I do see various DJI GPS units for sale, but I can't tell if they are compatible or recommended.

    I guess my main worry about the intermittent GPS is what would happen if -- after a good lock on home position for 30 seconds prior to take-off -- I lose control signal to the PV during flight, and it wants to come home. Without constant GPS will it get too confused and wander off? Other than that I can deal with the momentary ATTI-style operation. It just requires more input to keep things stable, especially in a little wind.

    Thanks again for your help.
     
  6. Chuggie

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    Location:
    Buffalo Wyoming
    It takes quite a while for me to get signal lock here where I live on the PV, I would say about 3 minutes after turning it on is average, and as much a 6 minutes before signal lock is complete.