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Thread: Strange unwavering signal near channel 8

  1. #1

    Default Strange unwavering signal near channel 8

    Can anyone help me guess what this strange signal is pictured here?

    I'm using Wi.Spy2.4i with Chanalyzer Lite.

    Near channel 8 (see red arrows) there is a constant signal of constant strength. You can see the solid light blue line in the recording, and in the average strength chart you can see that this signal is of constant strength, note the empty black stripe beneath the solid light blue dot.

    On the list of networks and SSIDs, there is NOTHING set to this channel. When I walk around, all the other signals vary in strength as one would expect but this particular one remains absolutely constant no matter where I go.

    Perhaps it's something generated by the very laptop I am running the analyzer on? But what? The laptop does not have bluetooth, no wireless mouse or anything obvious like that. I turned off the bluetooth on my phone (and did not take it on my walkaround).

    Ideas?

    Click image for larger version. 

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  2. #2
    Join Date
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    Default

    It is most likely interference from a USB 3.0 port.
    Here is a white paper on the subject from Intel.
    Note the graphics on pages 8, 10 and 16 of the report.
    Old Mod by the Sea

  3. #3

    Default Interesting info re USB3, but I'm not convinced.

    First of all thanks for the paper on USB 3 interference, it's an interesting read.

    I have this WiSpy 2.4i plugged into a pretty old laptop, and I didn't even know it has a USB 3 port but it does. So my first thought was "Aha!". But reading the paper you quoted, I would not expect the port to cause such a tight and consistent interference pattern as what I've shown in my graph. I would expect more of a general rise in the noise level across the spectrum. That's my interpretation of the paper and its charts. Also, I'm not using my USB 3 port so I assume it would not be transmitting a constant high level of noise. That's an assumption, it could be wrong.

    The signal is whacky. I should try putting the wispy in a different laptop and see if the first laptop is the source of this noise. But that means convincing someone to let me install Chanalyzer lite on their laptop. Here goes ...

  4. #4

    Default

    I also recommend trying it in a different machine to see if it goes away.
    Joel, Mobility+, ECSE, CWNE #233
    Technical Trainer
    MetaGeek

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