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Moved GPS antenna, GPS is drifting badly

Discussion in 'DJI NAZA flight control system' started by stevemaller, Jul 29, 2014.

  1. stevemaller

    stevemaller Heavy Lifter

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    Oct 19, 2012
    Half Moon Bay, CA
    Posted by stevemaller, Jul 29, 2014 #1
    I have a big quad with the NAZA-M V2. In an attempt to isolate my 1.3gHz vTX antenna, I tried moving my GPS puck as far forward as I could on my big quad. I have a CF boom out front for my gimbal, so I put the antenna (mast and puck) out there. GPS fix was horrible before, and it's great now. I have 13 sats and get the many flashing greed LEDs after 10-15 seconds. I went in to the NAZA assistant and set the antenna location to -30, 0, 4 (I did measure it). And I re-calibrated the compass.

    I can take off and fly in Manual and ATTI, but GPS wanders pretty badly. It doesn't even look like it's holding at all. That's weird given all the satellites I'm seeing.

    I do have very big motors and props on her, but she flies OK in ATTI and Manual. The user manual says "Should you find the multi-rotor does not track straight in forward flight. Please carry out several more courses, the system will fix it automatically." I flew several short flights swiching back and forth between GPS, ATTI and Manual, but GPS didn't get any better.

    Is there a limit to how far away the GPS antenna can be from the flight controller box?

    Thanks!
     
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  2. cootertwo

    cootertwo Member

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    Oct 29, 2013
    oii0i0i
    Posted by cootertwo, Jul 29, 2014 #2
    I guess I still don't understand Naza, although I have several flying fine. But I too, at first thought that the setting in Naza was for the position of the GPS puck. BUT, I now believe it is the MC/flight controller itself, not the "puck". And to get the best results, the MC (motor controller) should be mounted dead center on the balance point. The "puck" can go anywhere, that isn't interfering with other antennas. Try setting assistant to where your MC/FC is, not the puck. I think you'll see a difference.
     
  3. kloner

    kloner Aerial DP

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    Jan 5, 2012
    San Diego
    Posted by kloner, Jul 29, 2014 #3
    I had naza when it first came out, got into fpv and went with a 1.3 video system, was super stoked. Later dji released a sat puck for it and got it, couldn't get it to lock in from interference, went as far as took off the fpv gear and withing 4 feet of the rig it'd go away

    All that said i was hanging out with a bunch of dragon link guys and they liked 1.3, all of them had sat nav and all of them worked. they all had inline filters on the 1.3, think it was low pass 1.3, but mighta been high pass. Johnny Meguerditchian on facebook would know all about it,,, it was his group saw doing it
     
  4. stevemaller

    stevemaller Heavy Lifter

    311
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    Oct 19, 2012
    Half Moon Bay, CA
    Posted by stevemaller, Jul 29, 2014 #4
    I'm certainly no expert, but I am pretty sure the configuration parameters are for the GPS antenna, not the main flight control unit. The assistant software says "Make sure the location and oreintation of the Main controller and the GPS is correct, and then fill in the distance between body center of GPS and the C.G. of multi-rotor." The first time I moved the GPS antenna, I forgot to adjust the software, and the copter went nuts and flew away on me. I did update the parameters in the software, and now it's a little better behaved, but still not as good as before. However, I am also using 16" props now because my 14" props got tweaked in the crash landing. I think those props are way out of bounds, and maybe that's what's going on. eCalc says with 16" props my copter will hover at 21% throttle. That's way below the optimal efficiency curve for my motors. ;-)
     
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