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GPS issues with Phantom

Discussion in 'Phantom 1 Help' started by QuarkOfNature, Jun 4, 2013.

  1. QuarkOfNature

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    I'm having a problem with my phantom, where it no longer seems to get GPS lock. It was working okay this weekend, but not always getting a lock quickly. I flashed my firmware to 3.12, and now I can't seem to get any lock whatsoever; nothing but two greens, then three reds, no matter what I do. I tried the IMU calibration in Naza-M, and the compass calibration with the GPS/ATTI switch, but neither seemed to do anything.

    I opened the case, and took a look at the connection from the GPS module to the NAZA controller, but everything seemed to be connected firmly.

    Could this be related to the firmware update, or is it most likely just a failing GPS unit? Is there any way to do diagnostics on the GPS unit? I was surprised to see that there didn't seem to be any way to use the Naza-M software to see the number of satellites acquired, signal strength, etc. Thanks in advance for any ideas.
     
  2. jumanoc

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    Are you waiting all warm cycle?... After yellow 4 blinks....warming... Phantom will check satellites. How long time are you waiting for final GREN - GREEN RED RED RED ? Is it happening on exterior open area ? In interiors never get satellites lock enough.
     
  3. QuarkOfNature

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    Yes, waiting until after warmup cycle (flashing yellows go away). End-state flashing cycle is two greens (in GPS mode, throttle down, not centered), three reds. I've verified that flipping to ATTI changes flashing cycle to 2 yellows, 3 reds.
    I've left it for maybe 30 minutes, outside of course, with unobstructed view of the sky. Nothing on top of the stock white plastic chassis except dji sticker.
     
  4. jumanoc

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    Had crashed phantom? specially bumping on top may broke easily the GPS plate. Suggest open shell, unfold GPS covering and check if it is broken. Watch this pict:

    [​IMG]
     
  5. QuarkOfNature

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    You, my good sir, hit the nail squarely on the head! I disassembled the top, removed the GPS unit, and sure enough, the antenna was cracked quite nicely.

    I don't relish the idea of paying $160 or so for a new GPS module...so I desoldered the GPS antenna from the existing board. It came off with just a little coaxing from the soldering iron and some tweezers. Now...how to get a new one. I could buy an entire uBlox NEO-6M from ebay for about $25 (plus a 2-3 week wait for it to come from China). Can you get just the ceramic antenna piece anywhere? I'm not exactly what to search on, the part number printed on mine (1575R-A) doesn't turn up any promising hits.

    In the meantime, I removed the GPS board and thought I'd fly the phantom just on ATTI until the parts come in...but it seems the IMU circuitry might be on the GPS board as well? At least that's my guess...the phantom lets me fire up the motors, but then just tips over on its side helplessly as soon as I attempt to throttle up.
     
  6. jumanoc

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    Good to know where the bad boy is... I think you could fly ATTI mode too. Check if you reasembled top hull in correct orientation and propellers are also in the right position for turning according to direction showed on each arm.
    Really pricey GPS U$155 to u$185, but don't know if may be replaced with other brand - model... Checking in other forums... Good luck while get news around...
     
  7. QuarkOfNature

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    Yup, after posting, and playing around with the NAZA-M assistant software, I realized the IMU must be in the NAZA brain, not the GPS, and then noticed I had carelessly swapped a pair of the CW / CCW props in my haste putting it back together (for the umpteenth time, it feels). Flies just fine without the GPS.

    Also, I did some scouting online, and I believe I have located a compatible antenna. Here's the data sheet:

    http://www.taoglas.com/images/product_i ... 190410.pdf

    I ordered one from Digikey, for $4.73 plus shipping (a little better than buying a whole new module :) ). I'll post a follow-up if it actually works, in case anyone else has the same issue. Thanks for all your help jumanoc.
     
  8. QuarkOfNature

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    FYI, the part number so people don't have to hunt around in the spec sheet is: GP.1575.25.2.A.02

    And for folks who like pictures of broken stuff, here's the pic of my GPS antenna, left is while still soldered & taped to the module, right is after removal, which makes the damage much clearer.

    [​IMG]
     
  9. Sac D

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    [youtube]http://www.youtube.com/watch?v=LKAUQVu9v8U[/youtube]
     
  10. Racklefratz

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    So what's that square beige colored thing made of? It's the GPS "antenna"? Looks like plastic. Is there some kind of conductive material inside it that could function as an antenna?
     
  11. QuarkOfNature

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    I came home from work today to find the GPS antenna in the mail. I peeled off the cover from the tape on the new antenna, stuck the antenna to the GPS module board, soldered it in, and put the phantom back together.
    Of course it would be pouring rain today, but never mind, I went outside under an umbrella to see if it would lock up. Success! It acquired a full green lockup in about 10 seconds or so. To my surprise, when I was playing around with it a little inside the house later (to make sure stabilization was still working correctly after re-assembly, I noticed that it had acquired a full 7 satellite lock inside the house as well (two story foyer with windows, but still). So, I'd say that it looks like a complete success so far.

    To anyone else who has this issue, again, that was the part GP.1575.25.2.A.02, manufactured by Taoglas. I found it for sale at Digikey and Mouser, for less than $5 (plus shipping).

    Also, note that using flux is pretty helpful...I found it harder to solder in properly than most electronics, probably because the thick pin is attached to a metal antenna that basically acts like a heat sink.

    Racklefratz - The square beige thing is made of ceramic. The ceramic isn't the antenna, it's a housing for the actual antenna inside, presumably a metal tracing with the correct shape to pick up GPS signals at 1575 MHz. Here's an example of a GPS antenna, these guys sell clear stickers for auto windshields, so you can see an example of what the metal tracings might look like: http://clear-nav.com/about.html As for why they use brittle ceramic instead of some kind of sturdier plastic, I don't know. Perhaps the ceramic they use has better RF-transparency in the desired frequency range?

    Anyway, thanks for the help guys, I'm waiting for the next clear day to play with this thing outside and give GPS mode a workout!
     
    discv likes this.
  12. jezza1983

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    Exact same issue, checked it and also have a cracked Antenna. Many thanks for posting the part number online - saved me hours of research. Any other tips for removing and then adding the new piece? Fairly straight forward procedure?
    Thanks!
     
  13. allenj

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    QuarkofNature thanks so much for posting this info. I had a cracked ceramic GPS antenna from a crash a couple months ago and spent about $150 on a new GPS module. Luckily I kept my broken module.
    I think I will invest in this replacement antenna in case the crack happens again. Thankfully I am good with a soldering iron. It's really great to know that it's a very inexpensive fix and I really appreciate your detailed replacement info. Much appreciated!!
     
  14. Chrislille

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    I'm a french guy so i apologize for my poor english.
    Same issue with the GPS antenna after a crash with my phantom 2 in windly conditions. A 45 meters fall!
    Phantom 2 is very robust : no traces from fall inside an outside, flying again, just the GPS function out of order.
    Inside inspection shows me the cracked GPS antenna.... Totally sure it´s the same issue'
    I ordered the antenna on digikey website the 31th december. I received it in France the 3rd january. Great service!
    4 days after the crash and a little solder, the phantom 2 was flying again...... Just for 3.85 € plus 18 € UPS world wide express shipping.
    In France, my resseller told me u have to replace the GPS board for 150 €!!!!
    Thank´s a lot for this post... So much ;)
     
  15. ericty

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    Excellent info!
     
  16. Laid GP

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    Thank you so much! Just ordered one to fix the same issue with my Phantom.
     
  17. ercadm

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    I'm actually not sure if I have the same problem but ordered a couple of these GPS replacement units just in case. Although I have had my unit open a few times, most recently to replace the upper shell due to a crash that took out the camera cable and cracked the top shell but not near the GPS, by one of the rotors. I even had the GPS unit off but failed to look at the obvious cracks as I am only now reading this post.

    After installing the new camera cable I have the camera back but notice no display of satellites, distance/altitude. The thing is I have been out flying with the normal flashing lights of GPS lock before I take off of course. is there something else I should be looking at? Ie: compass?
     
  18. giodood

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    Hello,

    How would one install the GPS chip back on to the existing module? I crashed my Phantom full speed into my buddys house and cracked the GPS chip as shown above. I just ordered three more thanks to this thread and am just wondering how I would put the new one on once they come in?

    Thanks!
     
  19. vrso2

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    Location:
    Ocean county-NJ-USA
  20. vrso2

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    Location:
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    is my drone acting normally ??

    How stable is yours ?