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Tracking Down Wi-Fi Interference?
Nicros writes "Almost every evening, between 8:30 and 10:00, my Wi-Fi just dies. This, in itself, could be explained by a crappy Wi-Fi source or some hardware failure, except that I know both of my neighbors are experiencing the same loss of signal at the same time. While the Wi-Fi is down, the LAN is OK, and anything plugged into Cat5 can access the Internet just fine. One possibility comes to mind — perhaps some other neighbor arrives home and turns on their router from 8:30 to 10:00? And something in their signal is hosing our Wi-Fi? I have tried looking around for software to help identify the source of interference, but either the programs are ridiculously expensive for a home user, or else my card (Intel Link 1000 BGN) isn't supported. (Netstumbler is an example of the latter.) Any suggestions on how I can track this down?"
First thing to try is setting your AP to a different channel.
If that doesn't set you right, get a USB Wifi device that is supported under Linux and fire up Kismet and identify any strong signals nearby.
...put a sign in your front window or building lobby asking if anyone else is having the same problem, or uses electrical equipment only between those times. Make it a friendly note, with smiles, rainbows, and unicorns, so you don't offend anyone or make it look like a witch. As a bonus you get to know your neighbours.
If you are finding your fancy wifi card isn't supported by stumbler and other free channel overlap type tools . . . why not buy a cheap wifi card to use with those apps? You could always drop it back on craigslist/ebay (or even return it to the store claiming it doesn't match your curtains).
Talk to someone in your local ham radio club and see if they have a member with a spectrum analyzer and a directional antenna. Have them come out to the house and do some direction finding to determine who is transmittin on the WiFi freqeuncies in your neighbourhood.
Be polite. Ask nicely. Buy them pizza and beer to say thank you.
Hams are nice guys and gals and they will probably be happy to help out.
The ARRL website can probably provide a contact for your local ham radio club.
WiFi is an unlicensed service. Unlicensed services do not receive any special protection.
I've known a few people who had visits from the FCC for unlicensed transmitters...
I think it is caused by an analog 2.4 ghz phone, and someone chats during that time period. I had one of those phones and found that when I used it it hosed most of the available channels. Replacing the phone solved the problem and doubtless made my neighbors' lives easier. After a move, the same pattern showed up. The solution was a dual-band router.
It's an unlicensed service, provided you use licensed hardware to operate on it. That means, there's FCC certification behind all the commercial wifi gear you use. If you modify it or add on power boosting transmitters, you're using unlicensed hardware and the FCC will come after you.
8:30 - 10:00 could also be a baby monitor.
I'll never make that mistake again, reading the experts' opinions. - Feynman
Not at all. Changing channels is a low work method to solve the problem which will take little time. Since it may very well fix it, it is an efficient first thing to do. Who needs to know about interference on an unused channel? Additionally they may provide information. For example, If all channels are blocked then it is not likely to be another Wi-FI issue unless something is majorly broken (to the point of not functioning). If the quick, cheap and easy fail then you assign resources to the problem.
In fact not even with the trash. Soup and a tube work better and don't get players killed.
Then it's time some currently unemployed, enterprisey wireless technician starts a small company that resolves these conflicts.
Provided the FCC *will* act if someone provided them with tanglible and independently verified proof that a certain household or device is causing intereference, there's a business opportunity for someone with skills and interest in doing that.
I'm sure there's a lot of small to middle businesses out there that would love to have someone point out interference sources to their wireless infrastructure, since they more and more depend on all that DECT, WiFi and other stuff to properly work. Barcode readers, POS card terminals, RFID scanners, employee paging services - all those work in the same unlicensed 2.4 and 5GHz band and depend on all other equipment and operators to behave themselves.
One rogue AP operator illegally boosting a cheap home router to reach the edge of his yard can seriously hamper businesses half a kilometer around. Someone will pay money to pinpoint the source and resolve that issue, either by friendly negotiations or technician-approved notices to the FCC. The offender can then be sued for compensation, incl. the cost of the wireless tracking technician.
Maybe someone here gets an old van, puts cheap triangulating equipment inside and starts that business. The equipment costs about 10.000 bucks, this could repay itself in a few months....
Wouldn't it be better for detecting living babies? The dead ones would approach room temp and become "invisible" in the IR spectrum. The live ones should stand out like a sore thumb.
You do realise you're posting on slashdot?
Not everyone knows their mom as well as they should.
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Fair enough. But if a parent hasn't checked on their kid in enough time for decomp to generate enough heat to notice, I'd contend that the parent has other issues.
Not to mention your local ham operator:
1) Had to pass an exam about different types of interference and how to fix them (hint: it's not always the transmitter's fault)
2) Is likely to be passionate about avoiding interference to the point where he is unlikely to use those bands at high power in a residential area even though he has every legal right to do so. Think Linux fanboi level zealotry, but for radio.
3) Is actually familiar enough with ham radio to know that hams are extremely unlikely to use that particular band only during those particular hours, if they use it at all.
4) Is the least likely guy in your neighborhood to have noisy microwaves, cordless phones, or wifi, precisely because he doesn't want interference in his own ultra-sensitive ham receivers.
5) Is the one guy in the neighborhood most likely to have the skills and equipment to track down your interference. There are a lot of hams who live for that kind of opportunity.
Seriously, the FCC is unlikely to intervene without proof. Asking your local ham radio club for help, without blaming them, is probably your best bet.
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