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  1. Ben Morehead

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    SHORT FORM: RFI from my LG G4 phone was severely interfering with the GPS stabilization of the P4.

    LONG FORM: I was trying to guide my P4 through a long, narrow and winding creek covered with foliage, and before I could even begin the journey, the bird would jump up from 2-5 feet, all by itself, repeatedly. In short: a prescription for a crash. I brought a friend with me the next day to document it, and he was taking video with my LG G4 phone, while we watched the drone jump up dramatically when my fingers weren't even on the sticks. It was stunning. Then, after each take, we sat down to review the phone video, and there was no video there! Very weird. Then, it occurred to me that the phone was interfering with the bird, and vice-versa. Sure enough, we backed off 25-feet with phone, and the phone started recording fine, and the bird stopped jumping up autonomously.

    You can see the creek I was trying to navigate here: SkyPixel - Connecting Creativity

    I should tell you that this phone, like others before it, absolutely blots out the signal from my Toyota smart key fob. When the phone is in the same pocket as the fob, I can't even unlock the car, let alone drive it. RFI shielding is a real problem with most smartphones, and I'll bet lots of phones interfere with the P4. . .

    My $.02

    BHM
     
    deltalimatango and Phantomix like this.
  2. Geeno

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    I was reading another thread about this "yo-yo" effect. In my case, I attributed it to a after market gimbal guard. I searched and then found another similar P4 pilot have the issue and he also attributed it to the gimbal guard. Basically, i think the position of the guard would interfere with the sensors facing downward and give it a false sense of ground. So far, i chose to remove them and the yo-yo effect is gone. Just some additional thoughts to think about
     
  3. laserdoc85

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    Location:
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    I just flew this morning and I had the yo yo at about 50 feet. I did have a aftermarket gimbal guard on so next time I fly I will fly without it
     
  4. 28wins

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    It is recommended that, once one has cached the mapping data needed for the flight, the tablet be placed in AirPlane mode:

    1) to reduce/ eliminate RFI

    2) prevent messaging call/ alerts and other distractions during the flight

    3) recoup processing power and reduce power draw (useful since you'll be running at full screen brightness)

    4) eliminate one layer or complexity when/ if troubleshooting problems (no BT, WiFi or cell radio ON helps).


    It should be noted that the yo-yo effect was happening to people without a gimbal guard or anything affixed to the drone and with a tablet or phone in airplane mode.
     
  5. laserdoc85

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    So Im reading you right???? It made no difference if it was in airplane mode or had the guard on
     
  6. 28wins

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    From what others were saying, it may be something else.

    Search Results for Query: yoyo | DJI Phantom Drone Forum

    Search Results for Query: yo yo | DJI Phantom Drone Forum


    Question: do you calibrate your compass if you have moved away significantly from the previous location you flew at last?

    Do you perform a UMI Calibration after each firmware update?
    Are you running the latest firmware?
     
  7. laserdoc85

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    yes,yes and yes. Only have had the p4 about 3 weeks. First thing I did was to update firmware,calibrated both IMU and compass. Flying up the street in the neighborhood so have not gone far
     
  8. LuvMyTJ

    LuvMyTJ ADMINISTRATOR
    Staff Member

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    Time for an iPhone or Samsung. Why would you ever want to put that thing up to your head to make calls knowing what you know! :eek:
     
  9. ussvertigo

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    Do you turn off obstacle sensors? How low over water when yoyo occurs? I get unexpected rise when flying low to the water sometimes with sensors on, so I turn them off, it doesn't sense the water so well but when it does it starts to rise, not so good under tree limbs. This video was one I learned this on and has some neat low level flying over water.

     
    Erised likes this.
  10. Phillip LaRose

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    Location:
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  11. Phillip LaRose

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    I have had the same problem of the P4 rising and drifting when flying low over water. I have attached a video showing the P4 rising and drifting into a tree branch. I was flying about 6 to 10 feet above the water. The fix is to disengage the VPS system (Vision Positioning System) which is used for indoor flying below 10 meters and causes this problem when flying low over water. I have also attached a video showing how this fellow put tape over the sensors and the tests he made.
     
  12. ussvertigo

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    Don't need tape, just turn vps off. This can be done in Litchi which is what I normally use, I just checked dji go, and was surprised that it does not offer that option. I had same problem with my river video, even after I turn off oa and vps, flying manual I flew into a low hanging tree, through a lot of limbs and leaves before coming out under it, like me I bet it scared the hell out of you. I suspect the shade on the water had triggered the sensors. Great color, love low water scenes. My opening scene I noticed while skimming across the water the trees in the background are blurry, don't know the cause yet (camera setting).
     
    #12 ussvertigo, Sep 3, 2016
    Last edited: Sep 3, 2016
  13. Phillip LaRose

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    Yes, very scary. I was surprised I did not go in the water. Does turning off VPS in Litchi work? I read somewhere that it had no affect.
     
  14. ussvertigo

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    Hearing that I will fly this afternoon to test again, I actually by habit open dji go first, turn off oa, close go, then go into Litchi and make sure it's turned off there along with vps, and have had no further trouble flying within a couple of feet off the water under low hanging trees
     
  15. ussvertigo

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    Just tested turning off vps and oa in Litchi and it definitely is off, I was sorta sure from river shots but I'm glad you brought it up, gives me more confidence now.
     
  16. Phillip LaRose

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    Thanks for testing it. I use Litchi a lot and my next low flight over water I will use it to turn off VPS.
     
  17. ussvertigo

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    I hate to admit, but I have put 3 P2's in the water, all pilot error, but can't resist flying low over water. I now get in the water if I can, and with direct sight down the river can better judge alt above water, plus this P4 is so much more stable with it's alt than the P2 makes it a lot less nerve racking.


    Sent from my iPad using PhantomPilots
     
  18. Sky King

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    I have had a "yo-yo" issue for months. The latest FW was supposed to fix it. I was even a Beta tester for the FW. I have recalibrated IMU numerous times both at ambient temp and at refrigerator temp. Nothing seems to fix it. I am regularly 40' - 200' off altimeter readings upon landing. It, at times, will drop 75+' after a climb. Extremely frustrating.
     
    #18 Sky King, Sep 6, 2016
    Last edited: Sep 6, 2016
  19. Alien Warrior

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    Sent my P4 for repair to fix the yoyo effect. Everything above the gimbal was changed. No further issues with yoyo. P4 is now steady as a flying rock!

    Sent from my SM-G930F using PhantomPilots mobile app
     
  20. Dronego

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    Thanks for that, I was flying the other day and mine was jumping around and it scared me so I brought it back. I don't always use the gimbal guard but was this day. I never new why it acted up but you might have found the reason. I will fit it and see if it interferes with the sensors.


    Sent from my iPhone using PhantomPilots