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Thread: Mistake of not turning off wi-fi card when doing spectrum analysis

  1. #1

    Question Mistake of not turning off wi-fi card when doing spectrum analysis

    I was studying the CWNP book and came across this sentence on page 398: One of the most common mistakes people make is not disabling their WLAN radio from transmitting. etc, etc.

    The reason given is that: it this is not performed you will find very high-powered wireless transmissions in your spectrum recordings.


    The short USB extension cable would allow the Wi-Spy Dbx to be further away from the internal wi-fi network card. Or one could even use a longer generic extension USB cable.

    Does your own transmissions redden up the density display, etc????


  2. #2



    This is true, but as long as you know that the high readings you are getting are from your wireless card, you can keep it enabled. However, you can turn it off if you want and see the spectrum without it. Most people leave theirs turned on and as you get better at analyzing spectrum data, you will notice what probes look like and know what your wireless card is doing in the spectrum and rule it out as interference.


  3. #3


    Generally I leave mine on and it hasn't greatly affected my readings since I am expecting to have higher signal levels on my own network. However as a CISSP I advise people to turn off any wireless interface that isn't currently in use. With Windows machines you are broadcasting information about networks that you've already connected to, looking to connect to them again and exchange keys. Big security problem.

  4. Default

    The density display will not redden from probe requests. You will just see consistent noise across the entire spectrum in what looks like curves on each Wi-Fi channel.

    The activity is so minimal - I think you can leave it on - as long as you will not be confused by your WLAN activity.

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