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?"

Comments

report it to the fcc

[Surt]

Let them track it down for you, it's their job. Have your neighbors report the problem also. For 3 reports they'll be there next day with triangulation equipment.

Re:report it to the fcc

[Anonymous Coward]

Unlicensed means you can operate such a device without an operator's license.

It does *not* mean that the FCC doesn't care, or that they won't investigate interference.

Re:report it to the fcc

[FSWKU]

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference, and
2. This device must accept any interference received, including interference that may cause undesired operation.

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.

Re:report it to the fcc

[dattaway]

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...

Re:report it to the fcc

[GSloop]

I don't know if they'll come and check things out, but they do care about unlicensed bands - if you're way outside the power envelope allowed, I'm sure they'll whack you upside the head just as bad as if you were doing it in licensed spectrum.

Given the symptoms, I wouldn't be surprised to find something in the spectrum being used that IS outside the allowed power-limits.

However, I think you're more likely to get results if you find out what the offending device/person/entity is and asking them to help resolve the conflict. If they don't then you can move on to a complaint with the FCC based on power-output.

Re:report it to the fcc

[Urza9814]

...enter the FCC. That's kinda what they do....

Re:report it to the fcc

[GSloop]

You'll find a prior posted thread of mine about a spec analyzer. Perhaps it's out of financial range for the poster, since they seem to want a virtually no-cost solution, but I do offer suggestions on a spec analyzer for around $100, which is pretty good.

I didn't want to dupe that info in this thread, and it wasn't exactly the point of my post anyway. The GP claimed the FCC didn't care about unlicensed spectrum, but they do. However, they'll care a lot more if you show up with some real data - rather than "someone" must be doing something bad since my wifi doesn't work.

-Greg

Re:report it to the fcc

[plover]

Here's a cheap build-it-yourself spectrum analyzer: http://hackaday.com/2010/03/17/im-me-spectrum-analyzer/ The IM-ME can be had for about $15 or so, and is purportedly very hackable.

Re:report it to the fcc

[Bing Tsher E]

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.

Re:report it to the fcc

[davester666]

They won't do anything because it's due to a special satellite that happens to pass over his neighborhood everyday...

Maybe if he covered his router in tin-foil?

Re:report it to the fcc

[Cylix]

That device only covers 281 - 361, 378 - 481, and 749 - 962 MHz bands. It will not be useful for debugging the 2.4ghz spectrum.

There are likely some other options for a cheap analyzer around. I had some friends in a wireless shop convert an AP to a spectrum analyzer via a firmware update . However, those AP's were intended for commercial use and the price was a bit too steep.

Re:report it to the fcc

[labnet]

http://hackaday.com/2010/03/17/im-me-spectrum-analyzer/ [hackaday.com] The IM-ME can be had for about $15 or so, and is purportedly very hackable.

But it's... pink...

Re:report it to the fcc

[Atario]

So is your dick. Do you avoid that too?

Re:report it to the fcc

[Kymermosst]

The point was that say someone is operating under the part 97 (amateur service) rules in the frequencies of WiFi that overlap the ham band... who do you think wins?

The guy with the license, that's who.

Re:report it to the fcc

[Anachragnome]

"It does *not* mean that the FCC doesn't care, or that they won't investigate interference."

Investigate it yourself.

Go from house to house, both sides of your street, pounding on doors, yelling "I'm gunna start kicking some ass if you don't stop interfering with my WiFi Signal! Pussy! C'mon!".

The guy that DOESN'T come outside and kick your ass is the culprit. Speak to him privately after you get out of the hospital. I'm sure the two of you can come to a reasonable solution to the issue if you just relax and work things out rationally.

Re:report it to the fcc

[Quabbe]

That's the funniest thing I've read all day. Made me laugh out loud and show the guy next to me. I was having a shit day until now, thanks :)

Re:report it to the fcc

[jetole]

For about $30 - $40 you can get the Ubiquiti AirView spectrum analyzer usb dongle. From what I understand this will run on linux (don't quote me on that. I don't own one). http://www.google.com/products?hl=en&safe=off&q=ubiquiti%20airview&um=1&ie=UTF-8&sa=N&tab=wf

Re:report it to the fcc

[Anonymous Coward]

airodump-ng --showack -w output mon0

take note that all your idiotic neighbors all use channel 6 for everything.

decrypt WEP/WPA keys for router.

connect to router, login using default (never changed) credentials.

upload notepad.exe to router as a firmware upgrade.

no wireless devices running in range of your equipment.

Re:report it to the fcc

[ZigiSamblak]

If you live close to water where big ships dock then there's a good chance it could be radar. It may sound far fetched but it has happened before with a company who couldn't figure out why the entire wireless network went down every day at the same time. Turned out there was a harbour with big navy ships nearby, due to the tide the ships radar would be at a certain height at a specific time each day which would cause the radar to interfere with wireless signals.

Re:report it to the fcc

[Walt Dismal]

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.

Re:report it to the fcc

[phoenix321]

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....

Re:report it to the fcc

[fuzzyfuzzyfungus]

For shame, man! There is no way that your neighbor's router is licensed to run a copy of Genuine Microsoft Notepad.exe

Just use the first four megabytes that come out of /dev/random. Odds are that those 4 megabytes violate somebody's software patent; but at least the BSA won't be after you.

Re:report it to the fcc

[JackCroww]

This has to be an urban legend because the tide is not at the same height at the same time each day. The full tide cycle is roughly 12 hours, 18 minutes, so the time of high tide is going to be at a different time each day.

Try again.

Re:report it to the fcc

[dgatwood]

A couple of days ago, I was using my microwave oven while watching a MythTV stream over the Wi-Fi network from a laptop three feet away. Not even a hiccup.

The whole point of the design of a microwave is that the holes in its Faraday cage are much smaller than the wavelength of the signal generator within. If your microwave is wrecking your Wi-Fi connection, don't grumble about it. Get a newer microwave oven.

Re:report it to the fcc

[Tsu Dho Nimh]

You know I heard the same story ten years ago but it was that a server would spontaneously reboot. I have a feeling this may be an urban myth.

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.

Re:report it to the fcc

[Andy Dodd]

Unless the interference cause isn't subject to Part 15. The general pecking order in most of the ISM bands is:

Primary user: Military - They can run whatever power levels they want, and the secondary/tertiary users are screwed. However, the military typically stays out of the ISM bands because they're an interference cesspool unless they run crazy power levels.
Secondary user: Amateur (ham) radio operators - Legal limit 1500W, can't interfere with the military but can interfere with the tertiary user (but usually try to avoid doing so), and tend to stay away from the ISM bands for the same reason as the military. Occasionally hams will reclassify Part 15 devices under Part 97 (pretty much need to disable encryption and adhere to IDing rules), but it's very rare these days - just not worth the trouble.
Tertiary user: Unlicensed users.

The FCC is unlikely to investigate unless you have some evidence. Get a card supported by NetStumbler or Kismet (this won't help you much if your interference source is not 802.11), or get a 2.4 GHz spectrum analyzer such as the Ubiqiti AirView2-EXT ($60) or WiSpy 2.4x ($200).

I'm surprised that an Intel card isn't supported by any of the Wi-Fi monitoring tools. Intel cards usually are. (Maybe Kismet supports it but NS doesn't?)

Re:report it to the fcc

[vbraga]

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.

Re:report it to the fcc

[a_nonamiss]

I used the Wi-Spy 2.4i and easily tracked down a source of interference (in my case, a wireless rear-view trailer camera) in a crowded convention hall in a matter of minutes, and I didn't even know what I was doing at the time. It was crapping all over my Wi-Fi network, and as soon as they shut it off, I was back in business again.

I've since upgraded to the 2.4x model and track down Wi-Fi interference all the time. I would consider $99 cheap, consumer grade equipment. (Assuming you already own a laptop.)

Re:report it to the fcc

[mcgrew]

I certainly avoid everyone else's!

Re:report it to the fcc

[nametaken]

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.

Re:report it to the fcc

[Yert]

...except that local and state governments are forbidden by federal law to enforce ordinances restricting the construction or use of licensed radio equipment, including antennas, by lawfully operating licensed operators.

If it weren't for amateur radio, a lot of the technology you take for granted wouldn't exist, including your cellphone. Seriously, man, get a grip.

Re:report it to the fcc

[jjhall]

Normally I don't feed the trolls, but sometimes the trolls just beg to be fed a little bit of humble pie. It took all of about 20 seconds to find an article showing actual ham deployment, at the request of a local emergency agency, in the US. http://journalstar.com/news/local/article_84aba07a-3d9b-11df-8d7a-001cc4c03286.html A local news source including video from officials involved. Is that "reputable" enough for you?

And ham radio isn't just using "ancient analog technologies" to chat with each other about the bad conditions in nursing homes. While there is a lot of analog technology still in use, hams are also at the forefront of digital (extremely) narrow bandwidth communications development. The other thing to consider is that old analog technology doesn't stop working because one ham's clock is set a little off from another's, essentially what happened in Nebraska to take the 911 systems offline.

Ham radio is also not slowly dying as all the "old fogies" die off. The number of newly licensed hams is actually on the increase. http://www.ah0a.org/FCC/Graphs.html That data is sourced from the FCC license database if you want to go compile it yourself. There was a decline for a few years, but it is increasing in popularity again and is almost up to the pre-decline numbers. More and more young people are getting involved in ham radio. I know personally of several licensed hams who are 7 and 8 years old! The younger hams are very passionate about the hobby and more importantly the public service provided by hams.

As Random Coward pointed out above, if you think if the ham bands were suddenly taken away from hams that the spectrum would all turn into "part 15" unlicensed spectrum, you must not have taken your meds for a while. You said yourself how valuable the spectrum would be if it were to be auctioned off. Do you think the FCC and the rest of the government is going to donate those billions of dollars worth of spectrum to the public domain? They'll go the the highest bidders and they will be defended from illegal users (what "the people" will be) without end.

If you want "the public" to use the ham spectrum, nothing is stopping you from getting your license. It costs $14 to cover the expenses of the VOLUNTEERS who will administer the exam to you. Study materials are available at no charge all over the Internet. Once you have your license you'll be out a couple of hundred bucks for some radio gear to get started using the spectrum as you see fit (within the legal boundaries of course.) Ham radio is not about the "rich" people at all. It is just like any other organized hobby or service, you can do it relatively inexpensively or you can literally spend as much money as you want on it, depending on what you want to do and how far you want to take it.

Say what you will, but your argument doesn't hold water against verifiable facts.

Re:report it to the fcc

[kbielefe]

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.

Change channel / Try Kismet

[originalhack]

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.

Re:Change channel / Try Kismet

[PrecambrianRabbit]

But I want to watch Fox news and you're completely scrambling it.....

*confused* But I thought Fox news was already scrambled!

Re:Change channel / Try Kismet

[Cylix]

You can do the same issue with dd-wrt, but that only if the signal also conforms to the 802.11b specification.

A burst of noise or device using the spectrum differently will not display using such techniques. The spectrum is open and there are a number of protocols today that rely on those frequencies.

I had a friend with a 2.4ghz phone which would completely and utterly destroy our wireless reception.

Re:Change channel / Try Kismet

[Z00L00K]

That is assuming that the interfering signal is something other than noise.

Do you someone around that does a lot of welding? That's a lot of sparks flying around and it causes interference. Bad microwaves does too, but considering the time it's unlikely.

Radar is also a factor. Commercial and military communication as well.

Of course - it may also be someone's TV that's radiating interference. Especially old TV:s can be suspect. And other older equipment since RF filters may degrade by time - or the fact that they weren't tested for interference at the high frequencies that WiFi are using. 2.4GHz was something very exotic during the 70's.

Re:Change channel / Try Kismet

[X0563511]

You are all assuming it's another Wifi device.

By the exact timing, it sounds more like ordinary unexciting EM interference.

Re:Change channel / Try Kismet

[hpa]

Indeed... I put my 2.4 GHz AP on channel 1, because *all* the APs I could see from my house was on channels 6 and higher. It turns out to be a reason for that -- something that *isn't* 802.11 is interfering with the lower channels. Bumping it to channel 11 and all the interference problems went away.

Wifi operates in the ISM bands - the scrap heaps of the radio spectrum. There is tons of crap, and 802.11 is just a small part of that.

Re:Change channel / Try Kismet

[uniquegeek]

Sometimes the software on a pc or device shows it when you select a Wireless Network. Sometimes it doesn't.

Network Stumbler does.

Re:Change channel / Try Kismet

[cjb658]

1. Download a Ubuntu Live CD.
2. Open a terminal and type "sudo apt-get install aircrack-ng"
3. If aircrack-ng installs successfully (you may need to connect an ethernet cable to get an internet connection), type "sudo airmon-ng start wlan0".
4. Type in "sudo airodump-ng mon0" and you'll get a nice list of all the wireless access points in your area (even the hidden ones).
Aircrack-ng (and airodump-ng) documentation can be found here.

You can also try NetStumbler, which runs on Windows, but it much less powerful.

Re:Change channel / Try Kismet

[clone53421]

My parents had a wireless phone that killed the wifi every time it rang.

I changed the wifi channel. Problem solved.

It could be any number of things.

[IANAAC]

I had a neighbor that had an old 2.4 GHz cordless phone that used to interfere with my WiFi signal.

Once he got a 5 GHz phone all was well.

Long story, short: lots of things use the 2.4 GHz spectrum. It may not have anything to do with WiFi.

Re:It could be any number of things.

[fake_name]

We had a lot of trouble with wireless disruptions around our office - I eventually bought a Wi-Spy (http://www.metageek.net/) for $99 because the productivity loss was getting bad enough to justify the cost of the hardware.

Running a spectrum analyzer, and moving around the office (spending a few minutes in each spot ) was a great way to see what interference was where, and it's great to be able to "see" the 2.4Ghz spectrum instead of just look at what wireless networks exist.

Re:It could be any number of things.

[buchner.johannes]

Bluetooth is known to cause WiFi interference and degradation. Perhaps some Bluetooth-device is in use.

Don't bet on it being wifi.

[BabaChazz]

An associate of mine reported the same issue. In his case it was a failed security lamp that was trying to come on at sunset and failing; it was only when the ballast gave up after an hour and a half that his wifi -- and his AM radio -- came back. Note that many security lights are sodium arc or mercury vapor arc; not much is as hard on RF in general as a big fat arc.

Re:Don't bet on it being wifi.

[e4g4]

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...

Try it the low tech way...

[javaguy]

...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.

Buy a cheap supported wifi card?

[millisa]

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).

Re:Buy a cheap supported wifi card?

[AK Marc]

If $5 is out of his budget, then a call to the FCC is his *only* option. Short of waiting until the interference and cutting power to his neighbors one-by-one, it's the only free way to address it. And trust me, that one gets you in trouble. Used to be you could cut the phone line first, but no, cellular everywhere...

That's weird...

[Anonymous Coward]

That's the same time I microwave up all my hotpockets for the next day's raiding Ice Crown Citadel...

Use your local ham radio club

[crath]

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.

Re:Use your local ham radio club

[bezenek]

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

Re:Use your local ham radio club

[mcrbids]

I would add only one detail: tune the AM radio up near the "high end" of the radio spectrum, around 1500 or so. That's the part of the AM spectrum that's closest to 2400 Mhz, and thus most likely to pick up the interference.

Re:Use your local ham radio club

[APL bigot]

It may in fact be a ham that is legally operating in the 2.4GHz band. Hams are licensed users of this spectrum, and have priority. They could be causing the interference (if in fact they are), and if so you just have to live with it, if it can't be resolved. Hams are also protected from interference (by law) from the unlicensed users of the spectrum.

And by the way, end users increasing the power output of a WiFi transmitter is not a good idea. It can cause interference on nearby spectrum, and increased noise levels in the band, which can defeat the purpose of the increase in the first place. This is not something that should be hacked.

Re:Use your local ham radio club

[bezenek]

A quick clarification: The top of the AM dial (around 1500) is 1500kHz, or 1.5MHz. This is not close to the 2400MHz, or 2.4GHz at which WiFi operates.

The ability to identify the origin of the interference using an AM radio relies on the fact that the interference is produced from a source (often an electrical spark or arc) which generates RF noise on the entire spectrum. The spark plugs in car engines are a notorious cause of this sort of interference. If the spark plug wiring in a car is not shielded properly, you will hear a whining sound on an AM radio which changes pitch as the engine RPM changes.

AM radios happen to be easy to find and are very good at "hearing" the noise produced by an arc. If the noise is something like a microwave oven, which produces RF energy only at about 2.4GHz, then the AM radio will not help you find the problem.

I hope this helps to clarify the issues.

-Todd

p.s. As an interesting experiment. If you have WiFi and a microwave oven in your house/apartment, start downloading a large file. Look at the download rate (300kB/sec. or whatever). Then, start the microwave and look at the download rate. Mine drops to about 10-20kB/sec., because the microwave interferes with the WiFi signal.

Re:Use your local ham radio club

[Anonymous Coward]

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...

Re:Use your local ham radio club

[Thelasko]

As an interesting experiment. If you have WiFi and a microwave oven in your house/apartment, start downloading a large file. Look at the download rate (300kB/sec. or whatever). Then, start the microwave and look at the download rate. Mine drops to about 10-20kB/sec., because the microwave interferes with the WiFi signal.

Here is another one. Put your cell phone in the microwave, and close the door. DON'T TURN THE MICROWAVE ON. After a few seconds, your cell phone should say, "no signal," or "out of network," etc. If your cell phone still has signal after 10 seconds, it's time to get a new microwave. The housing of your microwave is no longer acting as an effective faraday cage, and is leaking dangerous amounts of radiation.

Hey Nicros

[Anonymous Coward]

I'd help you buddy, but every night between 8:30 and 10:00pm I'm working on my microwave disruptor beam. If it happens any other time, let me know and I'll be glad to pop over and take a look.

Re:Hey Nicros

[Anachragnome]

"I'd help you buddy, but every night between 8:30 and 10:00pm I'm working on my microwave disruptor beam. If it happens any other time, let me know and I'll be glad to pop over and take a look."

Mike, that you?

In all seriousness, I knew a guy up in Alaska that was trying to do exactly that.

He lived on some undeveloped property, raised pigs and collected old cars--his neighbor prided himself on his carefully manicured yard. They did not get along. Things got tense until one day the neighbor called the cops on him during a BBQ...and the war started.

One day, I'm over at his place and he takes out this finely-crafted, solid brass gizmo with all sorts of gears and worm screws in it, about 4 inches to a side. Barely concealing his excitement, he explained that he got it from a buddy that used to work at the local Airforce base, and that it was used by aircraft landing in the dark or on aircraft carriers. It was the core of a device he was constructing--a microwave cannon...to be used in the war.

Apparently he had managed to obtain a device that directed microwaves into a tight, adjustable beam. I guess it was used as part of a microwave guidance system for aircraft. Anyways, he had also had a large section of copper pipe silvered and polished on the inside and had fitted a microwave generator from a commercial-grade microwave oven onto the device. Amazingly, the generator fit PERFECTLY into the beam focuser, almost as if it was Destiny guiding his hands (or the industry has standards for such things).

I moved out of the state before he finished it. As far as I know, his girlfriend had convinced him not to finish it. To be honest, the guy was starting to scare me as I began to think he might actually be on to something usable for it's intended purpose.

I told him that if it actually worked, and he settled matters with his neighbor in a more civilized manner, he could always mount the thing on a lazy-susan, put it in the middle of his yard, get a clock motor to spin it slowly in circles, and he could simply turn it on to mow his yard. Flatest mow-job in town.

Also, InSSIDer

[millisa]

inSSIDer
I've been pretty happy using that to help find the best channel for my WAPs in congested areas. If you really believe it might be a neighbor jumping online from 8:30 to 10, that could help. I haven't yet found a card it doesn't work with under windows (assuming you are running windows...)

Re:Also, InSSIDer

[noc007]

Third this. It's a great app and gives you a simple easy to understand view of the APs that are in range. If it's a bunch of APs turning on at once, you may be able to pick a channel that will work better.

If it's annoying enough, MetaGeek has their Wi-Spy line of Spectrun Analyzers that will give you a better detailed view of the spectrum and not just a map of the APs in your area.

If your WiFi card supports 802.11a (5GHz), an investment in a new AP may be the way to go. The 5GHz band isn't utilized as much as the 2.4GHz band and isn't susceptible to interference from microwave ovens. My apartment complex is riddled with APs and no one is using 5GHz. Though if a faulty street light ballast is the culprit, it may put it interference on 5GHz along with a number of other bands as well and your investment in new hardware not effective.

have you tried...

[uniquegeek]

Happens the same whether you're on channel 1, 6, or 11? (the only b/g channels that don't overlap)

I know in my high-rise apartment, almost everyone is on channel 6, and I wouldn't be surprised if peak usage was mid-evening.

Did you double-check that some rule didn't accidentally get selected, which filters you out (either in the router interface... of you're using software that has scheduling...)

If you're using a radio type that is using the 5Ghz channel, someone's old beastly cordless phone might be affecting it too. If you're using a dual-band radio on your router, try using the other band and see what happens.

Running Wireshark (free) might not tell you what specifically is causing the problem, but you can narrow it down to see if packets are timing out, or getting filtered. Maybe there's traffic you didn't expect to be there? http://www.wireshark.org/download.html

Re:define "dies"

[Anonymous Coward]

For example I run netbsd on my wife router

NetBSD...it really does run on anything!

Did you get your wife from Stepford?

hard to solve

[Anonymous Coward]

I used to work several military trade shows at m last job, bringing in all kinds of weird stuff we were doing with wireless tablets and iphones and junk, just to show off what we could do... would stay up till 3am getting everything looking right, would show up 7:30am to make sure the morning of everything was good to go, then boom 8:30am rolled around and everyone fired up there demo hardware and all wireless in the building stopped working, it was ridiculous, happened at three different shows, we kept buying nicer wifi gear each time and failed miserably, until the 4th show that year and a particular company no showed.
The next show they were at and sure enough everything came down not just for us but all the booths in the hall and the hotels wifi, it did not take us very long to get a group together and head over there with the convention staff demanding that they shut everything down until they determine which device was the issue.
They had some very unhappy phb's screaming about ruining there day, but we didn't care, i got my 125 dollar dinner and it was all good.

Cordless phones

[Dan B.]

I will add my 2c and say it is the increased usage of cordless 2.4GHz phones during those hours. Some of the (cheap) units don't behave particularly well with WiFi and I've personally seen just one phone cause a complete outage of all WiFi in a house.

Chances are that one of your neighbours with a teenage daughter bought some cheap but funky looking cordless phone off eBay and uses it every night during your outage window.

InSSIDer

[whoisrich]

Netstumbler did not support my wifi card but came across InSSIDer which is free, and allowed me to easily see channel usage in the neighbourhood. They also sell USB spectrum analyzers for non wifi interference which is what you may need. http://www.metageek.net/products/inssider

Re:Agree - Old wireless house phones!

[Anonymous Coward]

This is exactly the problem we had with our apartment neighbor's teenage daughter. 8:30pm -10:00 pm fits the high school homework phone schedule.
A gift of 5 GHz wireless phones to the neighbors (in exchange for their old phones of course) cleaned up our mutual WiFi problems.
Took the old phones and dumped them into ATT Wireless Store's recycle bin.

Spec analyzer mode on ubiquity equipment/AP

[GSloop]

Get either the USB stick or one of the 2.4Ghz supported AP's from Ubiquiti. [www.ubnt.com]

The newest firmware supports a Spec analyzer mode - quite good, IMO - and it's not limited to WiFi equipment - anything in the radio spectrum is "seen."

Their wireless bridges in the 5Ghz spectrum using N tech (dual spacial streams) are seriously killer too - if you've got a wireless bridge, or WISP type situation, it's really, really cheap stuff. I'm likely to end up with 2.4 ghz and 5Ghz units just for spec analysis on the cheap. The units then double as AP's / routers / Bridges. (And at around $100 each, they're pretty awesome - Bullet M5, and Nano Station M5's for example.Find a wireless N bridge that will hold links over miles that are that cheap anywhere else!)

For around $100 you could have a nice AP and a spec unit in the same hardware. Antenna, unless built into the unit is a bit more difficult/pricey, but still do-able.

Anyway, I've got a setup using them in a PtMP setup, and though it's not miles, I'm seriously impressed - and the cost factor is simply *insanely* cheap.

http://www.ubnt.com/

-Greg

Re:Spec analyzer mode on ubiquity equipment/AP

[pcjunky]

They sell a USB module for 2.4GHz that costs around $38.

A friend got us a suriund sound system for our entertainment setup that included wireless rear speakers. Couldn't use hte rear speakers as it clobbered the WIFI. These things transmit a constant stream a really do a good job jamming WIFI. Sounds like something like this may be happening to you. Would explain the time frame.

Part 15 devices...

[sillivalley]

As a Part 15 device, you have to put up with what other devices are doing.

My first guess would be a non-802.11 device such as a video or audio sender. They can take out many 2.4GHz channels at once, where a microwave oven usually only knocks out a couple.

One workaround is to go to 5GHz -- you're still under Part 15 and susceptible to interference, but there's less of it, a lot more channels, and you can find a 40 MHz channel for 802.11n.

Without something that acts like a spectrum analyzer (such as a real spectrum analyzer -- but some modern access points and other 802.11n devices offer spectrum analysis/FFT capabilities), it's going to be difficult to identify your interference source.

Using a simple reflector such as a parabolic reflector or a corner reflector, you might have a better chance at establishing a direction for your interference source.

General electrical interference

[Anonymous Coward]

Keep an open mind to ANY device which could be turning on and off during the problem times.
I also had this problem and after weeks found it to correspond with the watering schedule for my garden - the water pump was on the other side of the wall to my router and was causing the interference.

Re:Go 802.11n

[GSloop]

You realize that N doesn't spec frequency, right?

802.11n can run in 5Ghz spectrum, but can also run in 2.4 spectrum. So, simply saying "use N" doesn't mean anything in terms of frequency.

In fact, most of the "consumer-grade" 802.11n equipment is 2.4Ghz exclusively.

---
I'd mostly agree that 5Ghz spectrum will be less cluttered, but I'd also guess that decent equipment using the tech in the N standard will do a lot better in 2.4 than b/g will. Multiple spacial streams, and (when implemented beam-forming) as well as beneficial use of "multi-path" etc will probably make N a lot better in most environments regardless of spectrum.

Baby monitors -- evil incarnate

[Anonymous Coward]

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.

Re:Baby monitors -- evil incarnate

[eyrieowl]

it's the years on end part which kind of rules that one out, i think. op says it only happens for a couple hours each night. unlikely that's the only time when the baby monitor would be in use....

I had a similar problem

[sdavid]

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.

What's your location again?

[djupedal]

Check for any satellites that track overhead at that time.

I remember when they used to open electric garage doors around the neighborhood....

RF shielding paint?

[MikeFM]

Tried http://www.safelivingtechnologies.ca/rf/Products_RF_Shielding_Paint_HSF54.htm RF Shielding paint? I always wondered if such paint would help. Of course it might kill your cell reception. If so, might be fun to paint your apartment in it before you move or maybe your bosses office when he is away.

Re:Agree - Old wireless house phones!

[dmneoblade]

Nowadays it might be better and cheaper to go with 1.3 Ghz phones. Uses the TV bands that were freed up. I have one and have wonderfully interference-free calls.

Use a cheap (real) spectrum analyzer

[tehaynes]

Using the 'Spectrum Analyzer' features built in to most APs and wireless clients will only show you other WiFi traffic not noise (almost always true). Also, they are not very portable. The earlier post about asking you local Ham Radio club is a good idea if there is anyone available and many Hams don't have equipment to listen to 2.4 or 5 GHz. You can search on google and other places for a 'usb wifi spectrum analyzer' for less than $50 that plugs in to your laptop. Be careful and read the specs though as some required that you use them in DOS mode. This will let you look at the actual received power level across the whole spectrum. You can walk around with a laptop until you find the noise source. It is still a steep price to pay for a one time fix. If you are the crafty type you can get a ez430-RF2500 target board for $22 from Texas Instruments. You will need to search for a software load that make it a SA but the are many instructions online. If you don't want to roll your own and get a prebuilt solution you can use the Ubiquiti AirView2 for ~$40. This is a very nice tool. You could even split the cost with your neighbors or pool money or request the person with the noisy device foot the bill for finding it.

Re:Use a cheap (real) spectrum analyzer

[bassman998]

I've been using the Wi-Spy from Metageek at work. I hadn't heard of the Ubiquity AirView. It looks like it's pretty competitive with the Wi-Spy -- apparently it uses the same chip, and the software has similar features. It'd be great if the AirView software had device signatures, but it appears that they're pretty receptive to feature requests through their forums. I'll definitely have to keep that product in mind as a recommendation to others. Thanks!

Wi-Spy USB Spectrum Analyzer

[bassman998]

Metageek has a few products in their Wi-Spy USB Spectrum Analyzer family. The cheapest one (the 2.4i) is $99, and the next model up (2.4x) is $199. It analyzes the entire 2.4GHz spectrum using your laptop and lets you see potential sources of interference. The 2.4x version allows you to use their more advanced software which also has device signatures -- you can overlay signal patterns of various types of devices (microwave, cordless phone, wireless baby monitors, etc.) on top of the signal density graph in order to identify what's causing the interference. I use the DBx version (2.4 + 5GHz) at work, and it's great for helping to find problems.

Re:Go 802.11n

[Will.Woodhull]

While this branch of the discussion is technically interesting, I don't think a technical solution that allows pollution to continue unchecked is as appropriate as a political solution of identifying the polluter and requiring him to clean up his act. RF interference, which is probably what is going on, is definitely a form of pollution.

Is there a railroad yard or industrial site that is using remote controlled locomotives or other RC equipment in the neighborhood? The intensity of interference and the consistent schedule suggests something industrial. Possibly something that is designed to function inside a Faraday cage but the cage has been left open. It can seem awful convenient to inexperienced technicians to just leave the cover plate off so they can more quickly do the scheduled inspections and servicing....

I think you've got enough evidence to involve the FCC. So long as they are aware of the timing and do the testing when things are on the fritz, they should be able to either rule out RF interference or find the cause fairly quickly.

Re:Agree - Old wireless house phones!

[shawb]

8:30 - 10:00 could also be a baby monitor.

Re:define "dies"

[smart_ass]

For example I run netbsd on my wife router and if the wifi interface goes down or stops working I would look in /var/log for trace information.

Your wife router ... come on ... Slashdotters are bad ... but you maried your F-ing router?

Xirrus

[malbrech]

Google xirrus wifi monitor. Is a free wifi signal monitor.

Re:Agree - Old wireless house phones!

[rapiddescent]

+1 - we were given a baby monitor that transmits live video and source temperature. It destroys our WiFi capability - but only within 20 metres or so.

Re:Try it the low tech way...

[Anonymous Coward]

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.

wow. you have not met my neighbors.

Problem with that idea...

[Demena]

Fox and CNN supply different data. A Wi-Fi channel carries the same data. A difference that makes no difference.

Voodoo?

[Demena]

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.

Not during a boss fight I hope.

[Demena]

In fact not even with the trash. Soup and a tube work better and don't get players killed.

Android + WiFi Analyzer

[Dynamoo]

If you have an Android phone, you can download a free application called WiFi Analyzer by Kevin Yuan which scans signal strength and can identify possibly interfering networks, pretty much like NetStumbler but in a more convenient package. If you are patient enough then you can map out signal strengths in various locations when you have GOOD reception, and then compare them to what happens when you have BAD reception and see where the interference is worse.. if it's a rival WiFi network then it should be even easier! But as others say.. the source of interference could be one of so many things in the 2.4 GHz band including DECT phones, baby monitors, microwaves or even just plain old fault equipment

Look for antenna's

[Taelron]

Growing up a friend of mine had a CB base station and a Ham radio, not satisfied with the range on his CB Base station he added boosters to his system. Any time he fired up his Base station to full power, TV's for a block or so went out everytime he key his mic. Look around and see if you see any radio antenna's around the neighborhood. Could be an overpowered CB or Ham Radio operator that gets on at that time every night.

Re:Agree - Old wireless house phones!

[Dachannien]

and source temperature

I know this is probably for detecting a fever. But I just wanted to point out that it's also good for detecting dead babies.

Re:Agree - Old wireless house phones!

[SQLGuru]

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.

Re:Try it the low tech way...

[BarryJacobsen]

As a bonus you get to know your neighbours

You do realise you're posting on slashdot?

Not everyone knows their mom as well as they should.

Re:Agree - Old wireless house phones!

[molo]

That is not correct for North America. The 700MHz band is what was freed up, UHF channels 52-69. Channel 69 was at 800 MHz. The highest channel ever allocated was 83, at 885MHz (rescinded sometime in the 80s). There was no 1.3 GHz broadcast TV channel in the US.

-molo

Re:Agree - Old wireless house phones!

[zill]

Decomposition generates a lot of heat...

Re:Agree - Old wireless house phones!

[SQLGuru]

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.

Reminds me of one I heard a while ago.

[Ungrounded Lightning]

Caveat: IBM customer engineer involved -> my tech-ish brother -> me. Take with requisite amount of salt.

Was shortly after the "foreign attachments" decision in an IBM antitrust case, which required IBM to post specs and allow other companies to build and plug in peripherals. During that period a bunch of multivendor projects got started - and many were the rounds of finger-pointing when it came time to integrate the products of a half-dozen or so vendors into a delivered system. This was one of 'em.

The system was being integrated at the install site - a building at an airport. Every piece had worked just fine in the vendors' labs. Nothing played well at all on the final site. Was a madhouse of vendor engineers trying to get things to play together.

At one point one of the engineers got sufficiently bugged by a flickering fluorescent light that he decided to do something about it. He got a ladder and turned off the lights preparatory to doing the fix - but the tube kept flickering. "Hey, guys. Look at this!"

Turned out the airport's search radar was right next door to this wooden building. Anyone familiar with transistor circuits and the number of volts-per-inch of signal strength needed to light an unpowered fluorescent lamp knows what that means.

They paneled the wall with aluminum. Everything started working. All shook hands and went home.