Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: Could use some noob assistance

  1. #1

    Default Could use some noob assistance

    Did a scan at one of my warehouse facilities, we have roughly 35 cisco 1242 radio access points with directional antennas up aisles literally stacked 40 foot high all at -10 degrees. I am getting interference you can see the blue lines, know what this could be?

    beth 91213.wsx

  2. #2

    Default

    First, 2.4 GHz band interference sources vary by country. There are far more uses of the ISM band in the UK than in the US.

    You seem to be in an industrial environment. Possible sources of the signals you are seeing include electric motors and machinery, sodium lighting, radar, etc. That said, I've not seen such solid, across the board signals before.
    Last edited by ua549; 09-13-2013 at 03:39 PM.
    Old Mod by the Sea

  3. #3

    Default

    Quote Originally Posted by ua549 View Post
    First, 2.4 GHz band interference sources vary by country. There are far more uses of the ISM band in the UK than in the US.

    You seem to be in an industrial environment. Possible sources of the signals you are seeing include electric motors and machinery, sodium lighting, radar, etc. That said, I've not seen such solid, across the board signals before.
    I am in the US, I found that odd as well and really didn't notice it while I was on location but after viewing my recording I realized it was there. I had another questions in utilization view the dark red on channels is just to be interpreted as several users or is it several devices on that channel?

  4. #4

    Default

    I can't answer your last question. I'll ping Joel.
    Old Mod by the Sea

  5. Default

    Hey guys,

    Sorry about my response time on this. Haven't been trolling the forums like I used to.

    I see what you mean by "blue lines" in the waterfall view. Something is turning on and off randomly.



    Whatever it is, it's raising the noise floor to about -90, which probably won't totally kill your network, but it is significant! The heightened noise floor is also very even across the band, which instantly makes me think out-of-band interference.



    Color by Utilization shows us that when it turns on, the duty cycle is more than 50 percent (red), which means that it is constant, like an air horn.



    I think ua549 is right, it's out-of-band interference of some type. A large piece of equipment, lighting, an electric motor, a cell tower... they key is to find whatever is switching on and off and see if it syncs with the activity in the waterfall view. These can be tough to find... if you figure it out, be sure to let us know!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Current.png 
Views:	164 
Size:	24.0 KB 
ID:	921   Click image for larger version. 

Name:	Density.png 
Views:	164 
Size:	150.9 KB 
ID:	922   Click image for larger version. 

Name:	Waterfall.png 
Views:	187 
Size:	209.4 KB 
ID:	923  

  6. #6

    Default

    Thanks for the analysis, that makes sense. We are a refrigerated warehouse and there is a engine room which runs freezers but it's behind two concrete walls but I would say that would probably be my culprit. I just got the device finder I am going to use that to see.

  7. Default

    That's probably it then. Keep in mind that the Device Finder is best for narrowband transmitters, but let us know what you turn up!

  8. #8

    Default

    Joel

    Would it be correct to say that this interference is at an amplitude that is unlikely to cause any real harm to your network?

  9. Default

    Quote Originally Posted by svosper View Post
    Would it be correct to say that this interference is at an amplitude that is unlikely to cause any real harm to your network?
    From a distance, probably, but if users reported problems, I wouldn't be surprised.

  10. #10

    Default

    I went back to this site recently and found a problem area for all the blue waves of full band interference. Above you mentioned it could be lighting, we have a 3rd party who installed motion controlled lighting that uses 802.15.4 Zigbee which is on 2.4ghz as well. It seems to be chattering on channels 3 & 4 but could this be the source of the full band, not familiar with that standard but in my googling I have found some remarks that it can interfere with 802.11g.

Page 1 of 2 12 LastLast

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
  •