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Telstra Blames Beer Fridge For Network Issues
Network Engineers Hunt Down Interference Wherever it May Be
by Karl Bode 02:07PM Monday Jul 15 2013 Tipped by JimThePCGuy See Profile
There are plenty of things that can cause interference with wireless networks (faulty ATM, lights or signal boosters), and you can now add beer fridges to that list. Using "software robots" to scan network performance logs, The Herald Sun says that engineers for Australian telco Telstra identified a strange signal that was disrupting cell service "several neighborhoods." After driving around using "Mr Yagi" antennas to seek out the origin of the signal, the engineers wound up at the source: the motor of a beer fridge in one man's beer refrigerator. "We just look at them all and go after the ones that are worst and approach it that way," says Telstra. "There's no particular focus now on beer fridges."

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jchambers28

join:2007-05-12
Alma, AR

yep slow day

Yep it's a slow news day for karl posting about beer fridge. I bet he is wishing that he was at home sucking down a few beers.

Smith6612
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North Tonawanda, NY
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1 recommendation

Re: yep slow day

On the plus side, it helps perhaps the less educated understand that even out of the box thinking can be required to troubleshoot Wireless. Maybe Wireless problems aren't always the fault of the ISP's supplied equipment

battleop

join:2005-09-28
00000

1 recommendation

Re: yep slow day

This kind of stuff is one thing that I don't miss about wireless.

meeeeeeeeee

join:2003-07-13
Newburgh, NY
said by jchambers28:

Yep it's a slow news day for karl posting about beer fridge. I bet he is wishing that he was at home sucking down a few beers.

Yeah, but, can the guys in the NEXT article turn the beer fridge into a spying device? If they CAN, they have a job with NSA for life!!
--
"when the people have suffered many abuses under the control of a totalitarian leader, they not only have the right but the duty to overthrow that government." - The U.S. Declaration of Independence
Kearnstd
Space Elf
Premium
join:2002-01-22
Mullica Hill, NJ
kudos:1

I wonder how they get these issues fixed

I have no clue how AUS works but if this were in the US could say the FCC even demand a shutdown of the fridge? since a fridge is not an FCC device.(like say how any electronics are part-15 devices and if they cause a problem must be replaced.)
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[65 Arcanist]Filan(High Elf) Zone: Broadband Reports

koolman2
Premium
join:2002-10-01
Anchorage, AK

Re: I wonder how they get these issues fixed

I want to say yes, they could shut it down or confiscate it. The device is transmitting interference on a licensed frequency. No device may do that unless licensed, and devices that do are subject to FCC rules.

Of course, IANAL, and I do have limited knowledge of this kind of thing.
cablemanf250

join:2013-07-15
Ive seen it happen with Hot-water Heaters, A/C units, & believe it or not we had one were a treadmill was causing issue's, 9 times out of 10 its a grounding issue with the appliance, we can put a Return filter on the lines to block the noise (CATV that is) or the Cust. needs to to have it looked at & fixed.

djdanska
Rudie32
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said by Kearnstd:

I have no clue how AUS works but if this were in the US could say the FCC even demand a shutdown of the fridge? since a fridge is not an FCC device.(like say how any electronics are part-15 devices and if they cause a problem must be replaced.)

I would think it would be cheaper just to buy the guy a new beer fridge. One that won't cause issues. LOL. I sure as heck wouldn't complain!
--
The day the child realizes that all adults are imperfect, he becomes an adolescent; the day he forgives them, he becomes an adult. The day he forgives himself, he becomes wise.
Alden Nowlan

midwesttech4

@insightbb.com

Re: I wonder how they get these issues fixed

more often than not, that is the way this situation is handled. In my days scouting interference, we found that often times things that were causing them were just easier to give the person money to buy a new one. We stockpiled old tvs, antennas, commercial microwaves and in one case we even paid to have an old mans garage rewired (it was a long drawn out process where he somehow was exempt from being up to code).. Litigation is just so costly that its just easier to pay a smaller amount of front and be done with it.

tshirt
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said by Kearnstd:

I have no clue how AUS works but if this were in the US could say the FCC even demand a shutdown of the fridge? since a fridge is not an FCC device.(like say how any electronics are part-15 devices and if they cause a problem must be replaced.)

Careful, you could end up with a national "warm beer" zone.
raytaylor

join:2009-07-28
kudos:1
said by Kearnstd:

I have no clue how AUS works but if this were in the US could say the FCC even demand a shutdown of the fridge? since a fridge is not an FCC device.(like say how any electronics are part-15 devices and if they cause a problem must be replaced.)

In NZ, our equivalant of the FCC have had articles in their monthly newsletter where they tracked down interference to pump motors etc. Basically if it is putting out noise on a licenced channel or breaking the law, it must be switched off. For example- RSM would go and follow up on a complaint from a cellular operator about some noise on their channel, and even in unlicenced bands they would do the same if it was transmitting more than 4 watts eirp in 2.4ghz or 1 watt in 900mhz or whatever the general user licence is for the band it is interfering with. Typically in these cases its causing noise all across the spectrum though so it gets shut down pretty quick.

NZ's RSM usually aligns its policy with australia to meet market demand so i would say its the same over there.
Kearnstd
Space Elf
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join:2002-01-22
Mullica Hill, NJ
kudos:1
makes sense to just pay the person to replace. far easier than the other fights be it monetary via litigation and of course PR. And in the case of pump motors it would be impossible to tell a person they had to shut down their well water to protect licensed frequencies. Easier to fork the money over, replace it for them and no fuss. I bet many carriers even budget for such things.

I must say though RFI generated by devices that are momentary loads must be a huge pain to track down. Such as the fridge in the article, the guys tracking it had to basically get lucky and be in the area when the thermostat decided to switch the compressor on. Guessing its part science part sheer luck to find non constant RF generators.
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koolman2
Premium
join:2002-10-01
Anchorage, AK

Re: I wonder how they get these issues fixed

My cable company had a customer's blender take down an entire neighborhood whenever it was turned on. It took months to track down because of how intermittent it was. They just bought a new blender for her.
Kearnstd
Space Elf
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Mullica Hill, NJ
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Re: I wonder how they get these issues fixed

said by koolman2:

My cable company had a customer's blender take down an entire neighborhood whenever it was turned on. It took months to track down because of how intermittent it was. They just bought a new blender for her.

Ha I can only imagine the poor tech tracking that one. At least the beer fridge will run for several minutes. depending on what that customer was blending it may have only run for a few seconds.
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PaulHikeS2

join:2003-03-06
Fitchburg, MA
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Seen this before

In my earlier days in the industry, we had a neighborhood that would lose cable internet for an hour or so several times a week, always after 5:00 PM on weekdays and any time over the weekends.

Turns out it was someone's clothes dryer that was not grounded correctly generating enough interference to get into the homes cable wires and backfeed into the area node. Would happen when they were home from work doing laundry. Took a couple weeks to find the problem - this was around 1999 - 2000 if I recall correctly.
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rradina

join:2000-08-08
Chesterfield, MO

Beer Fridge Causing THAT Much Trouble?

How does a beer fridge generate RF interference to the point where it causes problems for several neighborhoods? Interference for the target house and surrounding houses seems reasonable but it sounds like this thing was somehow feeding interference into the power grid which was then acting like a high-gain antenna. I wonder if the area had above-ground power which further magnified the issue.
raytaylor

join:2009-07-28
kudos:1

Re: Beer Fridge Causing THAT Much Trouble?

said by rradina:

How does a beer fridge generate RF interference to the point where it causes problems for several neighborhoods? Interference for the target house and surrounding houses seems reasonable but it sounds like this thing was somehow feeding interference into the power grid which was then acting like a high-gain antenna. I wonder if the area had above-ground power which further magnified the issue.

The beer fridge motor putting out the interference could be close enough to the cellphone tower mast that the tower cannot hear the phones over the noise of the motor. Cellphones work with very weak signals and hate any noise. So if the cellphone tower cannot hear anything, it will stop all service for the area that it serves which could be several suburbs.
Jazzemt

join:2009-02-12
USA

Re: Beer Fridge Causing THAT Much Trouble?

Some of the worst offenders I have found are gas pumps at gas stations. They generate so much rf garbage that it is astounding that something has not been done about it.
rradina

join:2000-08-08
Chesterfield, MO
But don't motors typically create interference problems for much lower Mhz bands? I thought most of the cell communications were at frequencies that are less affected by such simple noise.

Way back when I was a kid, I recall the lower TV channels (I think 2-6) being very susceptible to mom's vacuum. However, channels 7-13 were less affected and UHF channels had almost no interference. Same with electrical storms. The lower channels would get scrambled by a nearby bolt but UHF channels would just get a few sparkles in the picture.

My understanding is that a lot of today's current cell signals are beyond even the UHF TV band.
InvalidError

join:2008-02-03
kudos:5

Re: Beer Fridge Causing THAT Much Trouble?

said by rradina:

But don't motors typically create interference problems for much lower Mhz bands?

It depends on the exact nature of the electrical fault. If there is arcing in the winding(s) or excessive arcing at brushes, it can generate harmonics across a very broad spectrum.

An ideal spark (the 'dirac' function in mathematics) generates a flat amount of noise across infinite spectrum.
rradina

join:2000-08-08
Chesterfield, MO

Re: Beer Fridge Causing THAT Much Trouble?

Regarding the perfect spark and infinite spectrum, where would lightening be ranked? A bolt causes far less interference for higher RF frequencies than lower RF frequencies. At times I listen to AM and/or short wave radio and frequently, electrical storm interference is present. If the storms are close, it's can become difficult to continue listening. There are generally no such interference problems for even FM radio (which is barely ~100Mhz higher) unless it's a close, intense storm.

I'm wondering if the beer fridge had some sort of electronic control circuit whose shielding failed and the SOC started emanating noise at an almost perfect-match frequency for the cell signals. To me that seems more plausible than the perfect spark. If the fridge was located right next to the tower, it makes more sense to believe it was affecting that tower's entire coverage area and not just a few neighborhoods. I also would have thought if it was right next to the tower, they wouldn't have had to drive around to discover it. They would have started at the tower and immediately detected and located the interference.
InvalidError

join:2008-02-03
kudos:5

Re: Beer Fridge Causing THAT Much Trouble?

The difference between lightning and a defective fridge is that lightning is a one-shot event while the fridge is on-going for several minutes. On AM, lightning interference will cause the RF stage to clip and since AM's demodulation scheme is simply a rectifier with RC filter, the clipping goes directly to the output and causes audible popping. With FM, lightning will momentarily introduce phase error in the signal but since it takes several microseconds for PLLs to track the phase/frequency shift, the effect on output is far more subtle. The main reason FM is more immune than AM is simply due to FM being much less sensitive to one-shot events.

As for his fridge having electronics, the linked article has a picture of said fridge and it looks like something from the 60s with the freezer in the top compartment inside the fridge so you need to open the fridge door to access the freezer door so forget about electronics. My grandmother had one of those; weighs a ton, uses tons of power but are nearly indestructible.

And for the fridge's location, it does not matter much: phones have omnidirectional antennas and would pick up the fridge's noise if it was in range regardless of where it is relative to the station. If the fridge was directly under the station's antenna array, the antennas are usually vertical dipoles several meters off the ground with their signature "doughnut" pattern which makes them least sensitive to nearby ground-level interference sources so "right next to the tower" is not particularly likely. Also, if the fridge was causing cell-wide outages, they would have known the source was practically on-site and wouldn't have had to send out "black spot" hunters with "Mr Yagis" to find it. What they most likely did is use triangulation from the tower to identify the general area where the interference came from (track attached phones and their signal quality reports to map the problem area) and sent spot-hunters there to pinpoint the actual source.
rradina

join:2000-08-08
Chesterfield, MO

Re: Beer Fridge Causing THAT Much Trouble?

Thanks for such a detailed answer. Very informative. I didn't click the link to see the problem maker. Yes, that's an old fridge.

I still wonder how it was creating the interference since I thought most long-life electric motors of the type used in compressors are induction and don't use brushes. If the unit is that old, the thermostat may have a mercury bulb. Perhaps that was arcing as the unit neared the end of a cooling cycle. I suppose there could have been aging coils that were arcing but that doesn't seem like the kind of thing that could go on for long before something completely fried or it caused a fire.
InvalidError

join:2008-02-03
kudos:5

Re: Beer Fridge Causing THAT Much Trouble?

said by rradina:

I still wonder how it was creating the interference since I thought most long-life electric motors of the type used in compressors are induction and don't use brushes. If the unit is that old, the thermostat may have a mercury bulb.

There are many types of AC motors and some of them do have brushes. For example, many pool pumps have a starter winding on their rotor and a centrifugal switch to disconnect it once the motor reaches its normal operation RPM range - I have replaced the centrifugal switch and brushes (the whole thing bolts on top of the otherwise exposed rotor end as one package) on my mother's pool pump once.

I know that any remotely modern fridge (30+ years) uses a sealed compressor-motor unit which makes it practically impossible for any RFI directly from the motor to get out by any other means than the electrical wiring. In that case, putting a simple grounded AC filter directly outside the compressor and wrapping the length of wiring between the compressor and filter in foil tape so power wiring cannot radiate it out would eliminate just about all interference.

But with such an old fridge, the guy would likely make up the cost of a new fridge on what he'd save on power bills over the next 7-10 years... and as was said by others, Telstra will likely pay for at least part of the replacement cost (ex.: if Telstra offers him a $300 fridge but he wants a $500 model, he pays the difference) instead of wasting thousands of dollars in legal fees to force him to either have it repaired (replace the compressor and convert to modern CFC-free refrigerants - likely more expensive than getting a new fridge) or get rid of it.

As for arcing, if it happens within the motor, airflow for open-air motors would cool minor sparks down before they hit anything (nearly all AC-powered tools use DC motors running on rectified AC and nobody worries about sparks from their brushes) and with old fridges made out of thick gauge steel and fiberglass insulation, there isn't much for fire to catch on - whatever heat sparks may have is quickly dissipated by thick steel. With sealed compressors, the sparks would be occurring in a sealed ~100% freon (old fridge) atmosphere at ~0C (the refrigerant's temperature after coming back from the fridge compartment) so not much chance of igniting anything there either.

While mercury switches may cause electrical noise when they make or break contact, they wouldn't cause much (if any) noise once switched on/off. Mercury vapor has a low electrical breakdown voltage which makes mercury bulbs specially vulnerable to arcing when switching large inductive loads at significant voltages. If a mercury switch was arcing under sustained heavy load (it would have to in order to cause minutes-long cellular service outages), the mercury would heat up, evaporate and build up pressure until the switch bulb exploded so this would be a rather short-lived fault condition. If the old fridge used a mercury switch, it would have to be through a relay to prevent the mercury bulb from entering a runaway fault condition where it cannot turn off. Worn contacts on that relay could cause their own sparking and they can continue working for quite a while in that condition. Most of the time though, they either end up stuck-open (metal sputtering accumulating on contacts preventing load current from passing) or stuck-closed. (contacts fused/welded together from localized melting and cooling once the melting allows arcing to stop and contacts to cool down.)

amenite
The Soylent - It's People
Premium
join:2002-11-21
Ridgewood, NJ

Non-interference beer cooling

For anyone who hasn't seen it and is concerned about interference form their electric motor powered beer cooler, a friendly New Zealander has an alternative solution:

»www.asciimation.co.nz/beer/
--
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jap
Premium
join:2003-08-10
038xx

Re: Non-interference beer cooling


As it turn's out your link provided just the thing I needed to turn a bad day around. Proper perspective of the world has been restored. Sincere thanks.
asterger

join:2004-11-26
Raleigh, NC
Surprised given the story's Australian origin, why the icon isn't Foster's? "Its Australian for beer, mate".

jap
Premium
join:2003-08-10
038xx

Re: Non-interference beer cooling

Author is Kiwi in Kiwiland, not Aussie.
asterger

join:2004-11-26
Raleigh, NC

Re: Non-interference beer cooling

Yep that's what I get for scanning vs reading an article.

syslock
Premium
join:2007-02-03
La La Land
Its American for beer. They hate Fosters... "We Ship that stuff to the Americans."
VB and XXXX are great Aussie beers.

jap
Premium
join:2003-08-10
038xx

Re: Non-interference beer cooling

said by syslock:

Its American for beer. They hate Fosters... "We Ship that stuff to the Americans."

Good to know. Raises Aussies a notch in my estimation. Never liked Fosters but subconsciously accepted the marketing and assumed it was huge Down Under. Like Bud Light is here. [heave]