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2 Phantoms fly together OK, but don't use GoPro WiFi?

Discussion in 'General Discussion' started by mikeydaddio, Mar 6, 2014.

  1. mikeydaddio

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    After flying my 1.1.1 for a month now, I've accidentally flown with the GoPro WiFi turned on more than once (button presses itself on the gimbal mount and I notice the blinking blue light on the GoPro after I land). I saw no ill effects. My home runs a 1000mW (yes 1 watt) WiFi router and I fly over/around the house all the time with no problem. My phone has been in my pocket with WiFi turned on, both connected to the home WiFi and not connected. No problem.

    So let's get this straight: you can fly 2 Phantoms at the same time in the same location and that's fine even though they share the same general band of 2.4 Ghz. But using anything WiFi is a no-no even though WiFi is on a separate 2.4 Ghz band entirely? Not sure I buy it. I'm thinking it might be a myth propagated by the desire to explain fly-aways. Has anyone seen a video showing clear evidence (proof) of WiFi interference with 2.4 Ghz RC models? I mean, I've seen crashes claiming to be caused by GoPro WiFi interference but no real tests proving it. In fact, some of the crashes look to be from something other than interference to me!

    Now, not that having the GoPro WiFi turned on is particularly useful. I'm just addressing all the warnings about flying with 2.4 Ghz WiFi devices nearby.

    Not advocating that anyone ignore the warnings BTW! We all fly with WiFi turned off as a precaution! Just trying to separate fact from fiction.

    Mike
     
  2. saltire

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    You could try flying your Phantom in an open area and use your go pro remote to change setting and see what happens not much i bet .
     
  3. ElGuano

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    The rc units frequency hop so you can use several Phantoms together.

    I'm not running the tests but I've seen enough to tell me it's not worth finding out. As you mentioned, I wouldn't use the wifi feature anyway. FWIW, I've heard multiple times that you may be OK just having the wifi on, but if you connect to the wifi while in flight, that's where the real problems start. If you're set on mythbusting, I'd start with that use case.
     
  4. netphreak

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    If your gopro has the wifi on and connected, you're transmitting a 2.4GHz signal less than a foot away from a 2.4GHz receiver. There's no way for the phantom to receive anything else from the phantom transmitter. That's why you want to leave the wifi off. When you get the phantom, the transmitter and receiver are paired to each other, that's why you're able to run multiple crafts at the same time.
     
  5. Eos630

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  6. ianwood

    ianwood Taco Wrangler
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    You don't understand some of the basic principles of RF signals. You are comparing two cars traveling safely down an 5 lane highway that is otherwise empty with one car traveling down the same 5 lane highway stuck right next to a big rig 18 wheeler truck that is totally out of control, changing lanes, swerving, etc. No matter how fast or slow you go, he's right there along side you swerving like crazy. You may get lucky but he may just knock you out.
     
  7. mikeydaddio

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    If you check the frequency of 2.4 Ghz WiFi channels:

    http://en.wikipedia.org/wiki/List_of_WLAN_channels

    You'll see that they are not even running on the same highway, so no matter how much they swerve, you shouldn't get hit. Although I hadn't considered that the GoPro is a transmitter sitting inches from the receiver. I guess that close proximity could cause issues even if the frequencies don't overlap just due to EMI.

    Mike
     
  8. ianwood

    ianwood Taco Wrangler
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    It's not EMI. It's attenuation slope. To use another analogy, imagine trying to hear someone whisper to you from 500ft away while you have a loudspeaker blaring right next to you. Even if the center frequencies are at the opposite ends of the ISM band, the attenuation slope dictates that there is probably not enough guard space at that close range. You would need some precision notch filters to make it work.