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2.4ghz vs 5.8ghz ?

Discussion in 'General Discussion' started by FC40 Pilot, Feb 21, 2014.

  1. FC40 Pilot

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    Hi. I'm just wondering what the differences are between the 2 frequencies ( controller not fpv! ) and whether the reduced power on the 5.8ghz causes any issues for normal flight compared to 2.4ghz? I should imagine that even though 5.8ghz as a lesser range it probably has a cleaner signal with less interference ?

    Thanks
     
  2. amrflyingdude

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    Without getting too technical and sound boring:

    - 2.4 is capable of passing trough some obstacles and has a much better range
    - 5.8 is broader, less crowded

    With this in mind you can see a few of the reasons why DJI chose 5.8 for the TX and 2.4 for Wifi
     
  3. FC40 Pilot

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    That's a useful bit of info, thank you.

    What advantage does a broader signal have ( if any )

    Thanks.
     
  4. ianwood

    ianwood Taco Wrangler
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    Higher frequencies attenuate more easily but can carry more data/signal capacity.
    Lower frequencies travel further and penetrate objects better but carry less data/signal capacity.
     
  5. Count

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    Please elaborate, ianwood. I am CERTAIN I am not the only one who is trying to learn more about this topic. Your brief comments already have taught me so much!
     
  6. FC40 Pilot

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    Hi. What's the compromise ? The FC40 is also 5.8ghz
     
  7. ianwood

    ianwood Taco Wrangler
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    Hard to elaborate as that represents the bulk of my RF knowledge! Let's see what else I've got...

    Despite attenuating faster, 5.8 is commonly much less busy than 2.4 in built-up areas. Imagine you're trying to talk to someone from across a large room. If there are 5 other people in the room talking, you should still be able to communicate easily. If there are 100 people in the room and they're all talking too, you will have a harder time.

    As far as frequencies go, they're not as cleanly separated as you may think. The actual signal used is a block of space centered on that frequency. Your home wifi is a great example of this. Out of 13 channels, there are only 3 that don't overlap. And that signal will also radiate into neighboring frequencies depending on its power level. Imagine a bell curve. Raise the power, the higher the curve, the more the edges of the bell reach out beyond their intended frequency.

    Lastly, proximity is everything. The closer you get to something on a nearby frequency the more likely it is to effect you. This is why flying a Phantom close enough to the TX of an active high-powered mobile mast will eventaully cause loss of control despite being on totally different frequencies. Mind you, you have to get pretty **** close in most situations.

    I should mention how spread spectrum and frequency hopping techniques work to help avoid interference but maybe someone else can cover that.
     
  8. BruceTS

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    iOS/Android devices are fixed to 2.4, so to use those devices DJI had to use a different frequency for their controller, that's the compromise. This sucks if you want to run an aftermarket Tx, unless you go UHF, since most are in the 2.4 range.
     
  9. ianwood

    ianwood Taco Wrangler
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    Most current iOS and Android devices support both 2.4Ghz and 5.8Ghz Wi-Fi. It is true that 2.4GHz APs are still far more common the 5.8GHz APs.
     
  10. JKDSensei

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    So....a Phantom 1.1.1 on 2.4Ghz will have a greater range than the 1.1.1 that came with 5.8Ghz

    Nearly a mile with a bone stock P1 - 1.1.1 - 2.4Ghz vs around 400meters on a bone stock 5.8Ghz 1.1.1

    (ideal conditions, direct Line of Sight)

    YMMV
    If I was looking for a P1, I'd get a 1.1.1 on 2.4Ghz

    I got my 1.1.1 brand new for $280.00 (Delivered). 2.4Ghz, dual antennas, Naza M V2..... BadaBing.
     
    #10 JKDSensei, Sep 24, 2015
    Last edited: Sep 24, 2015