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Cell sites and power lines - Myth? Paranoia?

Discussion in 'General Discussion' started by FatKevinSmith, Jan 26, 2014.

  1. FatKevinSmith

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    I do know that if you were to fly something with a 2.4 or 5.8ghz receiver into the Fresnel zone of a 2.4 or 5.8ghz point-to-point link, it would at least temporarily drown out your transmitter's signal. Thing is, those point to point links could be miles long, and you'd have no idea you were even in the path. Those links are generally 50 to 200 feet above the ground, with the Fresnel zone being anywhere from a 10 to 50 foot diameter from the center of the beam.
     
  2. FatKevinSmith

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    Cell sites often use 2.4 or 5.8Ghz point to point links to create a mesh network (that is, to allow engineers to get into and manage the equipment). Those frequencies are not, however, used to communicate with phones.
     
  3. ianwood

    ianwood Taco Wrangler
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    True. And while cell towers don't normally use 2.4 or 5.8 for backhaul, a lot of companies use them for metro area networks. And while there are laws limiting power output, there are ways to legally pump out 60 watts from a wifi repeater. Fly into this guy's fresnel zone and your Phantom will no longer hear you:

    http://www.youtube.com/watch?v=Tdv_uwz3tf4

    Ironically, his opening shot is from a P2V. Anyway, that shouldn't stop RTH from kicking in and in no way should the signal coming from the Wifi station ever be confused for control input to the Phantom. At least, I hope it's designed this way. I have a Futaba RX because I don't think DJI's RX is as robust.

    As for cell towers in the US, we should all be a little concerned about Sprint running LTE in band 41 which is 2.5GHz. Most POPS are currently being repurposed from WiMAX to LTE as we speak. Supposedly tested to death and doesn't interfere with the ISM band but anecdotal evidence says otherwise in close proximity. Fly near one of these towers and you'll likely encounter a good deal of signal interference.

    As for power lines, they emit EMI. EMI will set your compass spinning and could interfere with radios (GPS, RX, TX) but only at significant power levels and very close proximity. Fly ATTI near power lines.

    As an aside, many cell tower and power line companies use drones to visually inspect them, so they're not all as bad as their made out to be.
     
  4. EMCSQUAR

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    Now that's funny - you're just tempting fate...lol
     
  5. EMCSQUAR

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    When I saw your video this came to mind...
     

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  6. Ton4

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    Good, let's get rid of the myths.
     
  7. EMCSQUAR

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    Cool someone is debunking some of the myths.
     
  8. Ton4

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    Btw, I just heard one guy ever saying he lost signal because of a cell tower (used to work for dji)

    Gopro wifi stories seem plenty though. And I would like to take my Ricoh Theta up one day. Guess I have to be brave as the CunningStuntFlyer I guess.
     
  9. EMCSQUAR

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    I've had mine do weird maneuvers and come to find out I bumped wifi button on GP3 when loading onto Zenmuse. I can attest to that fiasco - landing was a trick.
     
  10. Gizmo3000

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    I"ve been following all the forums for awhile, and I have seen a few instances where high voltage power lines appeared to cause a flyaway.
    as well as another video showing some really erratic behavior around wind mills.
     
  11. Ton4

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    My quad does strange things around windmills!

    [youtube]http://www.youtube.com/watch?v=vopEZtfLth4[/youtube]






    (disclaimer, attempt at being funny, windmills may cause real trouble for Phantoms)
     
  12. ianwood

    ianwood Taco Wrangler
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    If that was indeed a Sprint site, it was definitely not 2.5GHz. Those antennas are antiques, probably not even powered up. Sprint TD LTE radios look like this. And if you flew that close to one of these, you would lose control.

    [​IMG]