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Max distance before losing wireless connection

Discussion in 'Phantom 2 Vision + Discussion' started by optize, Dec 11, 2014.

  1. optize

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    If I'm watching the feed over from the iPhone, I lose a wireless connection after about 1200ft away. Is that normal?

    It seems though that I can continue to fly it with the controller though, as I was able to go backwards 100 feet and it re-gained a signal.
     
  2. Meta4

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    There are so many variables that there is no such thing as normal.
    Atmospheric conditions and geometry of the angles between your antenna and the Phantom's are big ones.
    Experiment and you'll get different results.
    Last week I managed to get out to 3200 feet but usually less than that.
     
  3. eyecon82

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    I get like 1500-2000 feet with fpvlr stage 2 in a heavily populated suburb with direct line of sight.
     
  4. msinger

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    The remote controller has a range of 2,400 ft. The Wi-Fi range is only 1,500 ft - 2,100 ft. That's why you still have control when you lose the Wi-Fi connection.
     
  5. djczing

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    I get 1400-1600 ft. with stock setup, and 3600ft with fpvlr stage 2 antennas.
     
  6. flyNfrank

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    Lower the camera view quality to lowest setting to better achieve max distance.
     
  7. flyNfrank

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    Also get the rear antenna wire out of the leg and use tie straps in this manner to keep the wire from flopping around. This will help you maintain a connection.
     

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  8. lsteigerwalt

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    Damnit Frank...why didn't I think of that...how much extra distance by moving the wire out do you think?
     
  9. msinger

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    flyNfrank, why does that work? Are you assuming the leg degrades the signal a bit?
     
  10. garrock

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    Yes... that makes sense. If DJI did not factor in the near field effect the plastic leg has against the antenna element, that will de-tune the antenna off of free-space optimum. Moving it away even a few millimeters can return the antenna to its free-space optimum; especially at microwave frequencies (ie 5.8ghz).

    If one were try do another test moving the antenna element away just a bit (not the whole tie-wrap distance), that might product good results too. Then the antenna element would not be so exposed.

    Good work !
     
  11. msinger

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    Any suggestions on a good way to test this while the bird is on the ground to see how much this change improves the distance?
     
  12. garrock

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    Since there are no RSSI or QoS (Quality of Service) numbers to compare, it would be difficult to come up with a ground-based setup.

    Perhaps... in an open area (to reduce multi-path reflection effects from sneaking around), move a some-what RF opaque object in front of the drone and see if the RTH function is enabled. (perhaps remove the props to prevent the drone from flying; don't know if that will work though.) And, you might have to find the right distance between the drone and transmitter for that to possible work. Even your body will affect the environment.
     
  13. msinger

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    garrock, so, this should make an improvement in theory. But, it would be extremely hard to measure the difference (if any).
     
  14. flyNfrank

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    I think the distance gained by doing this little mod is minimal. But it will help none the less. The main thing about this mod is, it will help increase the amount of direction you can have the quad pointing and maintain the signal. When it is in the leg, you are kind of limited to what direction the open part of the leg faces. Pulling it out as I did may help get at least a piece of signal but from all directions.
     

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  15. garrock

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    Yeah.. hard to measure. the simplest way is to fly out to the same distance (before and after). Then yaw-rotate the drone. A bit subjective I know but never-the-less.

    I think what FlyNfrank was pointing out is the antenna's might become more omni-directional if they are moved away from the plastic legs a bit. This obviously would help when yaw-rotating the drone at its max control distance. But also increase the signal gain a tad too since the antenna finds its optimum free-space tuning.
     
  16. CapnBob

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    I can't speak for dji, but when I was designing antennas, I didn't get them working in free space, and just throw them into the installation and ship.
    A plastic with a dielectric constant of ~ 2.7 - 3.5 that close to the radiating element can detune the antenna V.S.W.R. in a major way, so the antenna must be designed to work with the structure. In this case, removing the antenna from the structure it was designed for can actually detune it in the same way.
    You may be actually hurting the performance by moving it.

    Now, having said all that, I'll bet dji did exactly the former.
    They probably designed a simple sleeve dipole tuned for free space, stuck it into the skid strut, and let it go at that.

    You may indeed get some benefit from unsheathing the antenna, but perhaps no more than 1/4 to 1/2 db with pattern ripple in a 270° arc away from the skid strut. Inversely, there may actually be more shadowing in the direction of the strut. You also have the other 3 struts, the skids, and multipath from the camera/gimbal to deal with.

    I doubt that real world testing would show any discernible or repeatable results.

    A better exercise might be to extend the antenna lead and let it dangle an inch or so below the whole mess. Now there is an unobstructed 360° view.
    Not so great for longevity, though. ;-)
     
  17. garrock

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    That be my guess too.

    flyNfrank could very well be on to something. Especially near max distance and then yaw-rotating the drone.

    Need to fly down range to almost where the link is lost.
    Then do it again with the antenna away from the leg a bit.
    Might not need to distance the whole coax; just the antenna element.
     
  18. msinger

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    Any way to increase the length of the antenna? Then you could let it hang an inch or so below the landing gear.
     
  19. djczing

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    Up in the GHz frequencies, radio doesnt go through solid objects well - there is always loss, if it gets through at all.

    As far as making it longer, no - its cut to be resonant in a specific frequency range. I would more suggest an aftermarket antenna.