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Thread: 2.4GHz Warehouse Interference & RF Source

  1. #1

    Default 2.4GHz Warehouse Interference & RF Source

    Could anyone help me to identify the following RF sources?
    1. The first is frequency-hopping across the entire spectrum.
    2. The other is sitting to the right of Ch13 and there's a shadow of something similar between channels 6 & 11.
    Sorry there isn't much density to these plots ...
    Click image for larger version. 

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    Thanks in advance.
    Rich T

  2. #2


    Can you please either upload a larger image or the recording as it is really hard to see anything. Thanks.

  3. #3



    It' really hard to learn much from small JPEGs. If you can include a recording instead, it would be easier to answer with a little more confidence.

    1. May be your wireless card. Try scanning with your wireless card disabled (completely, not just in Chanalyzer) and see if it goes away.
    2. Way to faint for me to tell. Maybe with a recording, definitely with a longer timeframe. Not strong enough to cause meaningful interference if it stays this faint.

    Last edited by bret; 05-27-2011 at 01:30 PM. Reason: typo

  4. #4


    Hi Rich T,

    Looking at the FH signals it could well be ancient legacy kit used for a Warehouse Management System (WMS). I have a lot of experience of these systems in warehouses and am well versed with the waveform they present. The most popular kit was 2Mbps kit by a company called Symbol (who are now part of Motorola) which frequency hops right across the 2.4GHz ISM. It can interfere with any Wi-Fi AP within 5m of it. It is probably over eight years old at least...

    Not sure about the the CH13 kit except that in Europe we normally use Ch1, Ch 7 and Ch13 to give a better spread.



  5. #5


    Very interesting if Philbee's right! I'd like to have a recording of something like that.

  6. #6


    The Symbol/Motorola has also been in the 900MHz band for a while now too-

    Here is a recording (picture) of Wally-World using either a:

    902-928 MHz Motorola (Symbol) XR440 RFID Fixed Reader

    or a

    902-928 MHz Motorola (Symbol) MC9090-G RFID Mobile Reader

    NOTE: Ignore the spike at 915MHz as that is a TP1080WC (Tycon Power Weather Station)
    Also the lines at 912 & 924 MHz are Wi-Spy internal interference with the crystal/clock frequency.

    Click image for larger version. 

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    Attachment 461

    This was taken at a distance of ~3 miles from Wally World with a 9dBi Omni antenna, at a height of roughly 25ft.

    Unfortunately, I was not able to upload the recording as it is too large. Maybe the admin could make the *.wsr files allowed as large as the *.wsx files that are allowed.

    Last edited by oxygen69; 06-09-2011 at 02:50 PM. Reason: update info

  7. #7


    Per your request I have increased the size allowed for .wsr file attachments to match that of .wsx files.

  8. #8


    Thanks Richp01,
    However.... I tried uploading a 4.5MB file and the info (?) said I could upload a 9.54MB file, but it still will not allow 4.5Meg to be uploaded ?? (*.wsr file that is)

    Click image for larger version. 

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    Last edited by oxygen69; 06-09-2011 at 03:24 PM.

  9. Default

    Hey Oxygen, I put it up on our ftp if you'd like. Just send me an email with it attached. Sorry for the late response.

  10. #10

    Default something similar

    i have also seen something very very similar to this issue, i even turned off ALL wireless, my phone all APS, dect systems etc, and also took a control reading from my hotel room and could definatly not see this issue apear there.

    it seems for me it is hunting across from below the 2,4ghz spectrum and then to channel 11 hunts dowb a bit and then starts again.

    the problem with this interference is that is causing the exact same issue, our WIFI phones are not romaing and scanners data rates are going right down to 1mbps (we tried disabling 1,2,5.5,11 etc but as soon as we did that we got nothing, no connections in the trouble area)
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Attached Files Attached Files

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