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Thread: Unusual RFI Pattern

  1. #1

    Default Unusual RFI Pattern

    Ok, let me try this again…. I am seeing an RF pattern that is unusual. In the waterfall view, you can see blips that create stripes at a 45 deg angle over time and it appears across most of the lower channels. The attached jpeg illustrates the patter. Anyone know what causes this kind of pattern? (I am far from an expert at this stuff….)
    Last edited by MetaGeek; 10-22-2009 at 02:47 PM.

  2. #2

    Default This is just my

    This is just my thoughts....
    It kinda looks like channel scanning. I wonder if all the app traffic on those low channels is making clients scan for a clear service to connect to.
    Just a thought...

  3. #3

    Default I believe the "45 deg" stuff

    I believe the "45 deg" stuff is an artifact of the way the WiSpy works. You can change it's sweep rate in the hardware settings. If the "45 deg" changes too, then you are just looking at a beat/alias affect.


  4. #4

    Default Marty: I am concluding that


    I am concluding that you are right. Chanalyzer 3.3 Spectral View, which to my understanding is the same as the waterfall view, does not show the same chevron pattern.

  5. #5

    Default I have a similar looking

    I have a similar looking display ecept mine are over every single channel in the spectrum. It is like something is using a spread sprecturm methjodology instead of using a a single channel. I dont see how to attach a file of the spectrum but mine looks similar exceot the bell curve is over each channel between 1 and 11. Could this also be Spectrum analyzer ALIASING ??



  6. #6

    Default Have you got any bluetooth

    Have you got any bluetooth devices near the receiver? Bluetooth doesn't use a single WiFi channel, it hops across the entire 2.4GHz band. Try putting two cellphones near the receiver and sending a file between them by bluetooth. If that causes the same pattern of interference, bluetooth is the culprit!

  7. #7

    Default That look exactly what my

    That look exactly what my APs beacons look like.
    802.11 Beacons don't transmit on a single frequency.

    That looks like AP beacon timing vs Wi-Spy sweep time colliding.


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