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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?"
Meaning that the FCC won't do anything if your microwave is making your router go wonky. But since there is something causing outside interference to multiple people, they WILL track it down, as that means there is a device somewhere in your neighborhood that is violating the first part of the above condition.
"So after all this, you make my case for me. To end this stalemate, you must die..."
Baby monitors. One of the few devices that can completely trash all wi-fi frequencies in an area, not just for 1-20 minutes like a microwave but for years on end. Especially older models which use an analog signal.
First try what is suggested by BabaChazz in his comment above and is what most Hams would do to start. Listen for the noise on an AM radio. You do not want FM, as one of the characteristics of FM is to block this noise.
Take your (preferably hand-held) radio and tune it somewhere on the dial where there is no station. Then, you can try moving it around your computer to hear all of the RF interference your motherboard, etc. are giving off. If you cannot hear this noise, something is wrong with the radio--be sure it is set to AM. :-)
Leave the radio on, and you might hear the noise start at the time your WiFi drops. If you do not, the interference is not covering the AM frequencies (an arc will cover everything), and it is probably time to call in a Ham.
It is likely you will hear it.
If you hear it, you can walk around inside and outside your house listening for where the noise gets stronger. Often this will be tracked down to a phone pole or something else.
Once you find it, contact the appropriate person (electric distribution supplier, city, etc.) Convincing someone to fix a problem like this is not always easy.
-Todd
Omne ignotum pro magnifico.
Check for any satellites that track overhead at that time.
I remember when they used to open electric garage doors around the neighborhood....
This is very interesting - I've been experiencing extreme wifi interference issues since I moved to my new place (about a year ago) in Brooklyn. My neighborhood is not known as one of the more crime free boroughs in the city, and presumably as a result of that reputation, the neighboring building's backyard has an always-on sodium light at the ground floor (of the brightness and sickening color of your typical street-side sodium lamp). My bedroom (also on the ground floor, facing the backyard) experiences the worst effects of a very obvious latent interference in the area, that is lesser (but not gone) in the 5GHz range, but renders wifi nearly unusable in the 2.4GHz band (with the added interference of several other networks in that frequencey range close by - though there is 3 channel free band). I wonder if the sodium lamp is the issue...
The secret to creativity is knowing how to hide your sources. - Albert Einstein
Yes, we have priority, but we're not pricks. If someone came to my house to ask if my radio equipment is causing WiFi signal dropping from area houses, of course I'd be happy to help by solving the problem. Helping my neighbours change the WiFi channels or installing directional indoor antennas for them ($10 from DealExtreme) could help in this issue...
And here's another one along similar lines. Some time ago, someone's network went down regularly at the same time every evening. In the end, it was found that the bank on the floors below was turning on a microwave-based motion detector after closing. Perhaps in this WiFi case, something industrial or commercial is being activated nightly nearby? 8:30 to 10 seems a lot like cleaning staff hours. Maybe a floor polisher motor or vacuum with bad brushes putting out a lot of EMI.
No ... I was working in a Norfolk hospital lab when some idiot turned on the horizon-scanning radar for an aircraft carrier that was nearby - it should have been locked down, but wasn't. A lot of our electronics readouts went berserk from the induced interference, harmonics and other crap that thing was belching out. ICU had it worse because all their heart monitors and ventilators were affected. It was an interesting few minutes.
Found it:
From SAIL "autobiography" (here):
I got proper air conditioning a short time later, but unfortunately developed a bad case of hiccups that struck regularly at 12 second intervals. My assistants spent a number of days trying to find the cause of this mysterious malady without success. As luck would have it, somebody brought a portable radio into my room one day and noticed that it was emitting a "Bzz" at regular intervals -- in fact, at the same moment that I hicced. Further investigation revealed that the high-powered air defense radar atop Mt. Umunhum, about 20 miles away, was causing some of my transistors to act as radio receivers. We solved this problem by improving my grounding.
English is not my first language. Corrections and suggestions are welcome.
I wouldn't ever brick someones router, especially since they'd just go get a new one and we'd be back where we started. What I have occasionally done is survey from a friends living room, then connect to all the open and default pw'd ap's around their house and adjust what channels everyone is on. I mostly consider it a service to the neighborhood, but no, I do not go over to the neighbors houses and survey again to find out if they don't have a more distant neighbor that they're now banging heads with.
I kinda hate consumer wifi. I sometimes wish there were something governing its use that prevented there from being 300 routers for 300 tenants in one apartment building. It's especially nasty that AT&T rolls out their ewire devices everywhere for home dsl and doesn't care about their configuration other than to lock them down.