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WRT54G Interference - possibly involve FCC?

Discussion in 'Cisco/Linksys Wireless Routers' started by thoalex, Feb 8, 2005.

  1. thoalex

    thoalex Network Guru Member

    Ok, after messing around with my WRT54G for a couple of *years* now, I've come to the conclusion that there is interference in the 2.4Ghz spectrum that has to be interfering with the operation of the device. Here's my story:

    I purchased one of the original WRT54G V1.0 devices (still have it). For a very long time, I ignored it because I wasn't at home during the day. However, my wife informed me that sometimes when she tried to use it during the day that the wireless connection was out. I wasn't home during that time so I couldn't figure the problem out.

    Recently (well not recently but that's another horrid story) I've been unemployed and at home during the day. Over the past several months, I've been trying to figure out what's wrong with the wireless connection and I'd pretty much given up and figured that my original WRT54G was just a bad one. Since I was an early adopter that didn't surprise me. So I asked for a new WRT54G for Xmas and got one.

    So, I've been having some problems with the new WRT54G (they are different from this issue) but I'd also been having the same old issue of the wireless connection being out. I went and downloaded the latest Alchemy from Sveasoft and put that on my old router (which is actually a more stable router than the new one in my opinion) and had been running it for a few days. Today, the old problem appeared, dropped wireless connection, couldn't connect wirelessly at all. So I hooked up the new WRT54G and had the EXACT SAME ISSUE. Could NOT connect at all wirelessly to it.

    Here are my caveats:

    ALL of my wireless clients cannot connect (I have more than one and they are both B and G and from different vendors)

    It is NOT a channel issue. I can change channels all day long on the router and nothing effects it until the time period of interference passes

    When this occurs, it happens during the same period of time, sometime between 3pm and 6pm Pacific time. Occasionally I've seen it happen at other times but it is most consistently during those time periods. It is not for a few minutes either and it is random. It could be for 15 minutes it could be for three hours.

    In my opinion, the only thing that this could possibly be is that there is something in my area operating in the wireless spectrum and is knocking out my connections. If I were in an apartment complex I could understand this and would think maybe someone is on the telephone or a microwave oven is interfering but I'm in a house. If someone is interfering with me then they are broadcasting way too hot. This is considered illegal is it not? I'm thinking about writing a letter to the FCC about the issue but don't know if that would help me at all.

    Suggestions? Ideas? Anything?

    Thanks
    Thomas



    (FYI: I used netstumber today to see if I could see the Access Points at all, absolutely nothing)
     
  2. opjose

    opjose Network Guru Member

    FCC

    It is indeed likely that you are seeing exactly what you describe.

    However note that you may have a local transmitter that may be on a 2.4Ghz subharmonic and you are experiencing bleedover.

    In this case there may be little that you can do, as the offending xmitter may be well within limits.

    The problem with non-licensed band devices is that the FCC stipulates that they are required "to accept interference" from other devices.

    In other words, if something is causing you problems, then it's up to you to "reorient the device to avoid interference"... thus it's your problem so to speak.

    Is there any way you can determine what comes on during that time?


    I've been to places 3/4 of a mile from an AM/FM broadcast tower that picked up so much induced signal, that anything and everything that could, acted as an antenna.

    Telephones, faxes, even light fixtures all received the broadcast and produced their own resulting audible response....

    e.g. singing light fixtures, whistling fax machines, talking telephones (while they are onhook!)... etc.

    Very annoying, yet the transmitter is fully within licensed limits.
     
  3. thoalex

    thoalex Network Guru Member

    I live in a very generic subdivision type community. No telling what it really is. My *guess* however is that there are some very LARGE power lines very close to me. (I live on the very edge of town). Other than that, I can't figure out what could possibly be the problem.

    Is there a device (I"m sure it is expensive) that can determine if something is using the spectrum when I have the problem? Something like a geiger counter?
     
  4. howardp6

    howardp6 Network Guru Member

    You can use a sniffer, download and use Netstumber, if you wireless NIC is supported. You can use a hidden feature site survey, but you hard wired to the WRT54G. If you enter the ip address of your router for example 192.168.1.1.Site_Survey.ASP your router will search for access points that are broadcasting. It will not work for wireless telephones in the 2.4mhz spectrum of microwaves for that you need a scanner. Netstumber will give you the MAC address of the access point, its SS-ID and signal strength. If you have a GPS it will also give you the latitude and longitude of the AP.
     
  5. littlewhoo

    littlewhoo Network Guru Member

    Yes, that's right. Netstumbler or the SideSurvey page can't give you that kind of information.

    But if you are running a firmware, that provides console access to your WRT54G, you can use the wl rm_req and wl rm_rep commands to get information about interference on the single WLAN channels. This does not only include interference caused by other WLANs, but also interference caused by other devices operating in the 2,4 GHz range, like microwave ovens, babyphones...!!!

    Code:
    rm_req  Request a radio measurement of type basic, cca, or rpi
            specify a series of measurement types each followed by options.
            example: wl rm_req cca -c 1 -d 50 cca -c 6 cca -c 11
            Options:
            -t n  numeric token id for measurement set or measurement
            -c n  channel
            -d n  duration in TUs (1024 us)
            -p    parallel flag, measurement starts at the same time as previous
    
            Each measurement specified uses the same channel and duration as the
            previous unless a new channel or duration is specified.
    
    rm_rep  Get current radio measurement report
    (This does only work with a firmware version like Alchemy and most likely Hyperwrt, that includes one of the newer Broadcom drivers. The older Broadcom driver in Satori doesn't provide this option.)

    Edit: To get more information about the different types of measurements (basic, cca, rpi) please have a look at this page:
    http://www.cisco.com/univercd/cc/td...ent/cw_1105/wlse/2_9/u_gd/radio.htm#wp1617946
     
  6. thoalex

    thoalex Network Guru Member

    I tried the following:

    wl rm_req cca -c 3 -d 50

    and I keep getting

    eth2: Invalid Argument
    <and then the help message>

    ????

    Thomas
     
  7. littlewhoo

    littlewhoo Network Guru Member

    Try specifying the d parameter first. Usually this shouldn't make any difference, but you never know...

    wl rm_req -d 1024 cca -c 3

    or

    wl rm_req -d 1024 rpi -c 3

    which is more the thing you need, when trying to find non-wlan interference.

    Which firmware are you using?

    Are you sure, that your version of the driver is supporting the rm_req command at all? (If you type "wl -h" you'll get a list of commands, where rm_req and rm_rep should appear pretty much at the end of the list).

    What output are you getting, when running "wl ver"?
     
  8. thoalex

    thoalex Network Guru Member

    Try specifying the d parameter first. Usually this shouldn't make any difference, but you never know...

    wl rm_req -d 1024 cca -c 3

    or

    wl rm_req -d 1024 rpi -c 3


    Neither worked (same error message)

    which is more the thing you need, when trying to find non-wlan interference.

    Which firmware are you using?


    Alchemy-6.0rc6a

    Are you sure, that your version of the driver is supporting the rm_req command at all? (If you type "wl -h" you'll get a list of commands, where rm_req and rm_rep should appear pretty much at the end of the list).

    When I type in wl -h I get the list of commands and rm_rep and rm_req are at the end.

    What output are you getting, when running "wl ver"?

    It says:

    wl: 3.60 RC13.0
    wl:0 Aug 2 2004 14:32:51 Versino 3.60.13.0

    And before I forget.. thank you for your help!
     
  9. newcx

    newcx Guest

    I am having exactly the same problem. Does anyone have an update or know if another brand WAP would be better at rejecting interference?
     
  10. Boodah

    Boodah Network Guru Member

    Possible solutions

    I had interference problems starting when we moved in December; lots of wireless access points in my new neighborhood that were causing havoc with my connection. Solution? I bought a pair of Linksys high gain antennas and the problem went away completely. Granted, there's no guarantee this will work for you but I offer it up as a possibility.

    Another possible solution would be to get out of the 2.4GHz spectrum completely and use 802.11a which sits up in the 5GHz spectrum.
     

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