Results 1 to 5 of 5

Thread: Weird recording

  1. #1

    Default Weird recording

    Guys,

    I have a recording of a site which has been fine for ages. My Wi-Fi is on channel 8, and I am aware of the device using the bottom end of the spectrum across channel 1 and 2, it is a wifi camera on a fork truck. However, on the trace at about 11:22 the is suddenly a broad flat peak that goes from Channel 3 to 13, that makes most of the wifi devices drop out. It is there until 11:52, then intermittent until 1205 and then dissapears completely. This pattern is repeated regularly.

    Anybody ideas gratefully received.

    Thanks

    Andrew Gardener
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	cs-interference.jpg 
Views:	167 
Size:	98.3 KB 
ID:	591   Click image for larger version. 

Name:	cs-interference-2.jpg 
Views:	178 
Size:	95.4 KB 
ID:	592  

  2. #2

    Default

    where was the recording taken. Type of building. What sort of work happens there.
    It looks like a very strong microwave but seems abit to long unless someone destoryed there dinner

  3. #3

    Default

    Quote Originally Posted by Apcyberax View Post
    where was the recording taken. Type of building. What sort of work happens there.
    It looks like a very strong microwave but seems abit to long unless someone destoryed there dinner
    hi, this is a medium sized supplies warehouse with extensive metal shelving and mezzanine floor areas. Forklift trucks operate all day with cameras operating near channel 1. approximately 30 Operators with Symbol wi-fi connected barcode readers roam the area picking supplies. The Wi-Fi environment is entirely Meru AP300 series AP's all operating on channel 8 in their virtual cell environment.

    Thanks

    Andrew Gardener

  4. #4

    Default

    does the interference happen just in the day or at night as well.

    One of my fav ways to rule out equipment (if your allowed to do so) is to run wispy on a laptop when the interference is happening one by one turn off the mains breakers to the location. If the interference is still there when all is off you have ruled out anything onsite unless running off battery.

    If you see the interference disappear then see what the last breaker you turn off was and see if you can find it that way.

  5. Default

    Thanks for posting.

    The second image is a little more useful however if you have a .wsx you'd like to send me I'd appreciate looking at it. The wireless camera on the forklift seems pretty interesting.

    There are a few things that we can deduce from the capture. Whatever is transmitting makes the exact pattern as a HR/DSSS PSK modulation curve (802.11b). Its amplitude peaks at about -45dBm. Because it is occupying the same Wi-Fi channel as your WLAN, I am going to say with quite certainty that it is a Wi-Fi device in your network and that you are extremely close to the source and quite possibly it is your own laptop.

    Sometimes cards decide to malfunction and they'll blast ps-polls or a type of control packet making it impossible for others to contend for the wireless medium. If you have a second computer load up a linux livecd with wireshark and look at the packets going by. You'll be able to get a MAC address of the offender and track it down.

    Or when it is occurring track it down with the waterfall view in Chanalyzer. If it follows you it is your computer, if not walk until it is bright red.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •