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Beware Of 2.4 GHz Interference

Hemos posted more than 13 years ago | from the i'm-a-living-testimony dept.

Technology 191

RobinX writes: "If you have any combination of cordless phones, wireless ethernet, wireless video, or Bluetooth you could be having problems. I've got two different 2.4 GHz phone brands that are interfering with each other and with my home 802.11b wireless ethernet network. It seems that the 2.4 GHz range isn't licensed so companies are free to do their own thing. Check out this article for more." I've been noticing problems recently as well, between phones from the same manufacturer and the WaveLan cards.

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191 comments

Not quite right.... (1)

Bellwether (12891) | more than 13 years ago | (#998499)

This isn't quite accurate. There are two flavors of 802.11 -- Frequency Hopping and Direct Sequence. I believe the author specified 802.11b which is the Direct Sequence flavor used by Lucent's WaveLAN and the Airport. (I may be wrong about which letter is which.) Frequency hopping equipment will indeed cause interference with the direct sequence equipment, since it's hopping through the ranges used for direct sequence pretty frequently. In the lab we've seen about 30% packet loss on WaveLAN when streaming full speed over 802.11a using the Raytheon 802.11 chipset used in WebGear Aviators. The Aviators seem to be pretty resilient though, and aren't affected significantly the other way.

Beware Of Microwave Ovens .... (2)

geirt (55254) | more than 13 years ago | (#998500)

Microwave ovens operate in the 2.4 GHz band, and are poorly shielded high power transmitters. Wireless lans and other ISM band applications are low power transmitters, but many microwave ovens (especially older ones) radiate (read: interfere) more power than these low power transmitters are allowed to do, because of their poor shielding. I would be very sceptical to use equipment running in the 2.4 GHz for "mission critical" work. 5.7 GHz ISM band equipment would be a better choice.

2.4 Ghz Interference (3)

OceanWave (192467) | more than 13 years ago | (#998505)

Another often overlooked culprit around this frequency band is the microwave oven. These run in the neighborhood of 2.45 GHz (give or take). Even a small leakage from the RF shielding can produce a detectable signal on or about this frequency.

Also, the the band from 2.3 GHz to 2.45 GHz [arrl.org] is (and had been for quite sometime) used by amatuer radio operators. A higher powered ham tramsmitter could also be a source of interfere with this equipment. Technically, low-power consumer equipment should have been located on another band.

Poorly designed equipment can "mix" signals on different bands and hear interference on their operating frequency, also.

I think you mean 440Hz (1)

B4Eddie (141439) | more than 13 years ago | (#998507)

440Mhz is in the amateur radio service band. A warehouse full of lights putting out that freq would probably draw some vigilante action.

Re:Cooking with interference... (1)

pe1rxq (141710) | more than 13 years ago | (#998518)

2.45Ghz to be exact.
Although they are shielded they still produce a lot of noise (because a typical microwave can have up to 1000 Watts of output power). Most wavelan devices should besides a bandwith drop not have any real problems with it. Video transmitters do have problems with it!

Jeroen

Re:Commercial radio vs. my cellphone (1)

Lion-O (81320) | more than 13 years ago | (#998519)

and I'm pretty sure my cellphone isn't operating on the same wavelength as my radio and my TV.

Actually its neither one. The wavelength of a Cellphone is closer to the microwave then radio and TV. I don't have a technical explenatition but it has indeed everything to do with interference; one signal influencing the other.

Re:Regulations in the 2.4GHz band (1)

jfanning (35979) | more than 13 years ago | (#998520)

Bluetooth frequency hops at 1600 times a second. But from what I recall, IEEE802.11 hops at a much lower rate, just a few hundred times per second.

I also remember that if you installed a bluetooth device and a wireless LAN card in the same PC it would kill the LAN. But then I haven't heard anything more about that problem for quite a while.

Poor Receiver Design? (2)

Detritus (11846) | more than 13 years ago | (#998521)

Could this just be a case of poor receiver design? I've seen this is VHF/UHF receivers. A strong signal will produce intermodulation distortion in the front end and wipe out any weak signals. A good receiver will have a linear front end with a wide dynamic range. This costs money, which probably means that the receivers in consumer grade equipment are a major cause of the problem.

Precious little detail (5)

Adrian Harvey (6578) | more than 13 years ago | (#998522)

This article gives very little detail on whats going on here. They don't even say if the author even tried adjusting the frequency settings of the interfering components. 802.11 has 11 (in the US) -non Frequency hop mode frequency settings (most of which overlap) and selecting another one might have helped a bit!

Some background for the curious: 802.11 sends 'chirps' - the same bit is sent simultaniously on a range of frequencies, with some bits reversed. this is done to prevent interference, or blocking on one band from interfering with the transmition.

The channels look somthing like this (in ASCII anyway) (if this looks wrong, paste it into an xterm, or notepad, or somthing with a fixed-width font)

|
|............---7---
|..........---6---
|........---5---
|......---4---........---11---
|....---3---........---10---
|..--2---.........---9---
|---1---........---8---
+---------------------------------------------
frequency ----->

Note that the vertical axis doesn't represent anything, it's just used to stop everything going on top of everything else. The dots are there because slashdot slashes spaces, but leaves dots! Nor is this diagram accurate, or to scale or anything, it's just ment to give you the gist.....

Here each ---x--- is a range of frequencies over which the bits of the chirp are spread.

There only one set of 3 channels which don't overlap, so if you need more than 3 802.11 networks in the same place, you're our of luck.

If you run your network in frequency hopping mode, you only transmit one bit on one frequency at a time (chirps send about 12 bits), but change frequencies often, across the whole range (no channels) This means that interference on one range will only kill some of your data. You obviously than need to retransmit failed sends (by the time a retransmit happens you will have switched to a different frequency.

The quality of the hardware you use can also make a big difference. The better equipment uses two aerials, spaced apart, to prevent reflected signals and some other kinds of interference from silencing the signal. The idea is that if a signal and it's reflection interfere to create a minimum (no signal) at one point, there will be signal just a short distance sway.

Most devices just ship set to a channel, and it's nearly always the same one - surprise surprise - 1! I don't know about the phones, but they would probably be similar.

I guess no detail, or background research is about what we expect from ZDNet..... :-(

Re:This is only the beginning (1)

Lion-O (81320) | more than 13 years ago | (#998523)

I'd suggest you go over to the residential zones surrounding Lopik and talk to the people there. After you did come back here and we'll talk again.

Re:Commercial radio vs. my cellphone (1)

seldolivaw (179178) | more than 13 years ago | (#998524)

I'll buy that. Thanks!

But what is to be done about this? Surely those designing the technologies realized this would happen at the time? Isn't all this spare current running around inside my electronics going to damage it?

Most importantly -- who should I sue? :-)

Is anyone really suprised by this? (2)

Elvii (428) | more than 13 years ago | (#998532)

This reminds me of RC car days, when you carried 3+ crystal sets on you so you could change freqs that your servo/transmitter used. If someone else had your same freq at a race, and neither of you had spare cyrstals, SOL to one of you..

Same thing here, pretty much. A (semi-)open band, and people are gonna use it for pretty much everything they can. History repeats itself as always, go figure. Wish I knew more regs on this so I could say how things are supposed to be.

bash: ispell: command not found

Not Just Cordless Phones (2)

Bios_Hakr (68586) | more than 13 years ago | (#998533)

I saw a while back on Ars-Technica that some pagers and cell phones share the same freq as the master oscilator in AMD boards. When the pager went off, the computer would die! I think the guy fixed it by building a grounded box around the chip.

Shazbot! (1)

Ziktar (196669) | more than 13 years ago | (#998537)

Well, that prolly means that I'd have problems at college with suitemates having interfering devices. And I was so hoping to have that wireless ethernet surfing the net out in the courtyard...

Real problem? (1)

smcavoy (114157) | more than 13 years ago | (#998538)

First, I'm not a raido expert at all, but has anyone done real testing to see how each of these devices are causing each other problems. 2.4ghz has been un-lic for a while without problems, (yes it has gotten a lot more popular). I think some "real" testing should be conducted. I'd hate to see wireless devices take even longer to implement ...

isn't this... (1)

-brazil- (111867) | more than 13 years ago | (#998540)

... the band range the licenses for which the German government is about to auction off with an expected profit of $50,000,000,000 ?

No license (2)

pe1rxq (141710) | more than 13 years ago | (#998543)

Ofcourse they are not licensed, the whole idea behind this frequency band is that you don't need to have a license as long as you are using approaved low power equipment.

Jeroen

Re:No license (2)

luckykaa (134517) | more than 13 years ago | (#998545)

There's a power limit? Damn! I wanted to stick a 300 GigaWatt transmitter on top of my house.

Re:Beware Of Microwave Ovens .... (1)

Anonymous Coward | more than 13 years ago | (#998546)

http://rabi.phys.virginia.edu/HTW//microwave_ovens .html

leads directly to the interesting sentence:

The frequency used in microwave ovens (2,450,000,000 cycles per second or 2.45 GHz) is a sensible but not unique choice. Waves of that frequency penetrate well into foods of reasonable size so that the heating is relatively uniform throughout the foods. Since leakage from these ovens makes the radio spectrum near 2.45 GHz unusable for communications, the frequency was chosen in part because it would not interfere with existing communication systems.

So GSM bandwidths (900, 1800 and 1900 MHz) used with 2W emitters are already suspected of being able to generate a brain cancer or whatever unproven or undemonstrated organic disorder, ok ok ok

Now just tell me why o why known nocive frequencies (2.4+GHz) are to be used domestically, for whatever purpose, even at 150mW?

This looks to me like a major health problem in the feature, especially as this is to be taken at least as a little dose effect. Whenever some geeks around will assemble and put up such devices around their heads (very cooooool wearable networked computers) I cannot guarantee they won't be cooked at all. I'm looking forward to get some litterature regarding possible brain damages incured by weird/inapropriate consumer usage.

This case is simply interesting and deserves some follow up on the health point of view. I'll wait another 2-3 years prior trying them out.

Re:Not quite right.... (2)

Adrian Harvey (6578) | more than 13 years ago | (#998547)

You're right. Note also that direct sequence 'chirps' and Frequency hopping *shouldn't* interfere, as the FH signal should only be able to kill one bit of the chirp at a time... leaving the other 11(?) or so to get through intact.

Re:This is only the beginning (1)

pe1rxq (141710) | more than 13 years ago | (#998548)

You are right about radio and tv equipment being disturbed, but trains moving on there own is bullshit.

Jeroen

X10 Video Sender is a PIG! (3)

cshotton (46965) | more than 13 years ago | (#998549)

I can definitely confirm the problems referenced in the article. I had almost the same set-up, with a Sony 2.4 gHz phone, a BreezeCom wireless LAN, and the X10 Video Sender.

The short answer is that the X10 Video Sender is a piece of ca-ca and was the source of all of the problems. The other 2 devices do frequency hopping and spread spectrum transmissions to avoid (and compensate for) interference. The cheesy X10 device just blasts away on a fixed frequency with a very low quality transmitter that spills all over adjacent frequencies.

The best answer I found was to stick to 900 mHz phones and run a wire for video. I boxed up the Video Sender and gave it to my Dad. It was just a bad idea all around.

Re:Commercial radio vs. my cellphone (1)

petros (47274) | more than 13 years ago | (#998550)

Digital phones send bursts of high power signal so audio electronics picks it up a lot easier.

It's important to note that this is actually limited to digital phones based on TDMA (like GSM and IS-136), where the transmitter is switched on and off rapidly several times a second, since there are many phones (8 for GSM, 3 for IS-136) on the same channel, time multiplexed. Each phone is allocated a timeslot during which it transmits, and remains silent the rest of the time. CDMA based digital phones don't exhibit the same behavior... Put a CDMA phone next to a speaker and you won't get any interference, because the transmition is continuous (and it's also spread over a wider channel, this might have something to do with it too).

2.4 GHZ in France and US (1)

martin (1336) | more than 13 years ago | (#998551)

There's been some problems with France having to suddenly free up this freqency in order to comply with EU regs, as it was used by some (?)military kit.

Also in the US some old Life Support system used on 2.4Ghz for something. They were supposed to be phased out before y2k hit, but they weren't and test transmissions killed them (not to mention the poor humans attached to them at the time!).

Re:This is only the beginning (1)

Kanasta (70274) | more than 13 years ago | (#998564)

Hmm. It it's so bad that stuff like stoves can go crazy, what happens to people with bionic ears and pacemakers?


---

Re:This is only the beginning (1)

yuggoth (85136) | more than 13 years ago | (#998565)

You are right about radio and tv equipment being disturbed, but trains moving on there own is bullshit.

He is probably talking about model railroads. I consider this to be quite likely - during my first physics courses at college, the professor showed us as an experiment how you could bring a light bulb to glow by simply connecting two wires of a specific length to it and holding it in the proximity of a radio transmitter antenna with sufficient power. In fact, he told us that for some time, this was a cheap albeit illegal way for people to light up their garden sheds near a TV transmitter station in the first years of broadcasting. If the power cables to the model tracks and the tracks semselves have the right length (a multiple of the wavelenght broadcasted), it should be entirely possible that the trains could start running on their own.

Eh?! (1)

Anonymous Coward | more than 13 years ago | (#998566)

I've got two different 2.4 GHz phone brands that are interfering with each other

This is like saying "When I bang 2 cans together on my head, they make a noise." Of course they're going to interfere! They work on the same batch of frequencies, just like CB radios interfere with some radio controlled cars.

Coming up next on Slashdot, "When I go outside in the rain, I get wet. Why is that?"

Next they'll be posting ingredient lists from cans of beans...

Re:Commercial radio vs. my cellphone (2)

petros (47274) | more than 13 years ago | (#998567)

I know that cellphones broadcast unusually powerful signals in the UK (3 or 5 times greater than the rest of Europe)

Unless you have a pre-GSM analog phone, which I know nothing about, then no, cellular phones in the UK don't transmit a 3-5 times the power used in the rest of Europe. Handheld units for GSM 900 output up to 2 watts, and GSM 1800 up to 1 watt. In reality the power is usually less than that, and it's determined by the network based on the strength of your signal when it's received at the tower (ie it's going to be really low if you're really close to the tower, and much higher if you're far from the tower and/or there is something blocking your signal).

Re:FUD alert (1)

Anonymous Coward | more than 13 years ago | (#998568)

I agree 100% with your technical analysis, but lets reformulate it in layman's terms that will help everyone, without need of any specialized knowledge. It's a basic principle of troubleshooting life in general.

You say he should have unplugged the X10 first, not last, but if the X10 video sender is predominantly at fault, he'd have unplugged it first *and* last. When unplugging a device fixes a problem, you don't usually keep unplugging things. Instead, you say "Aha! found the problem" and stop -- or better yet, plug everything else back in.

This practice can cause untold grief - but it usually works extremely well.

This author assumed he had a generalized or cumulative problem. he probably got this idea from the service personnel he contacted, particularly (assuming the X10 video sender was primarily at fault) the X10 service people, who implied that 802.11b devices don't play well together.

Well you can hardly expect them to say "our device doesn't play well with other 802.11b devices", can you? Heck, they may never have thought of it that way. All they know is that they see 802.11b problems left and right. they don't know other companies (or device types) don't experience this degree of problems with each other. (or maybe they do, but they have a peculiar wish to hang onto their jobs and.or see their company stay in business)

When you find what you think is broken, see if everything else works together. If it doesn't you have an additional problem -- but there's no need to presume more trouble than you see.

It's just common sense... and we all know how tricky that can be!

Re:SOL? (1)

GRAMMERSoft (184119) | more than 13 years ago | (#998569)

Sausages on legs is the first thing that springs to mind

Freud would probably have something to say about that...

Re:This is only the beginning (1)

pe1rxq (141710) | more than 13 years ago | (#998582)

You need much more for a motor to run then for a light bulb to glow, a typical electric train runs at 12V with about 0.1A (some up to 0.5A) That would require at least 1W of power. To pick up this kind of power you would have to live VERY close to the antenna, and I know Lopik, there are only a few people living really close to it and I don't think anybody is that close to it. Besides Lopik doesn't cover the entire country, there are several substations accross the country. Which again is only a few hundred kilometers from one end to another.
Since a few years most transmittors have been moved to a more remote area in the FlevoPolder anyway.
Jeroen

Re:Commercial radio vs. my cellphone (1)

NKJensen (51126) | more than 13 years ago | (#998583)

What can be done?

Well, the basic thing to do is to prevent high frequency signals from entering you audio equipment.

How do the signals enter? By the wires. Wires with the right length function as antennas.

What can stop the signals? Anything with induction (coil) effects.

(Any amateur radio operator will know this, since they send signals with several 100 more power than any license-free device. Ask a HAM if you know one.)

Put a ferrite core around every wire leading to or from your audio equipment, as close to the enclosing as possible.

Look for ferrite cores in CB/walkie talkie shops or in HiFi-freak stores.

Re:SIGNAL_11 is a fucken idiot, Malda is his bitch (1)

Skapare (16644) | more than 13 years ago | (#998584)

In /. technogeek is the common language. Emmerse yourself in and learn.

Those problems aside.... (1)

sleeperservice (62645) | more than 13 years ago | (#998585)

We've been having these exact issues. Which is why we rolled out base stations to IT Operations for "testing" purposes at home and almost immediately ran into the 2.4 gHz cordless phone problem.

Having said that, once you're aware of the potential interference, wireless connectivity can be a real, real benefit. For base stations we're only using one official WaveLAN base station, and for the rest (including the home units) we're actually using Apple's Airport Base Stations, which are working very well.

The key to good performance, we've found, frequency issues aside, is to make sure to configure each base station to accept only certain mac addresses and space these out. This will ensure that if people walk around with their laptops, you won't suddenly have an issue where 30 people have a meeting and they're all using 1 base station. Especially if one of these is giving a streaming video presentation....

So, highly recommended, despite the various interference problems, which we've managed to overcome, to a greater extent. Just plan, plan, plan, as always....

Re:Commercial radio vs. my cellphone (1)

NKJensen (51126) | more than 13 years ago | (#998586)

The techincal explanation is about sum and difference frequencies generated by non-linear components.

Since you audio equipment is full of transistors and diodes (both of them non-linear) any incomming high frequency signal may be converted to a signal in the audio range. See my other comment about how to stop the problem.

Re:Commercial radio vs. my cellphone (1)

QZS4 (7063) | more than 13 years ago | (#998587)

But what is to be done about this?

You have several options: 1) Make sure you have a good signal strength to your base station (lowers the transmitted power from the phone). 2) Use an external antenna (moves the radio source). 3) Just move your phone a bit. The noise in my computer speakers vanish completely if I put my phone more than a meter away from them.

To get a good signal to the base station, move your phone around a bit. The signal can vary a lot in a small area. It also saves your battery - keeping in contact with a bad connection sucks much more power than with a good signal strength.

Re:Get some DECT phones instead (1)

pastie (80784) | more than 13 years ago | (#998588)


I'm cautious of the analogue cordless phones (some operate around 900mhz though) because they're so open, it creates problems with eaves dropping and people "borrowing" your phone line


In fact, there were (still are?) enough people with analogue cordless phones about that you could wander around in a car with a handset until you got a dial-tone, then park up and "borrow" their phone line for a while ;-) [I'd assume that this isn't legal though]

Disclaimer: I, of course, have never done this myself... ;-)

No You Can't (2)

frog51 (51816) | more than 13 years ago | (#998589)

Most countries in the world limit the 2.4GHz band - although it is unlicensed - by power output. The US gets 1 Watt max, UK and Europe get 0.1 Watts (France keeps changing its regs) and the Middle East still hasn't fully complied:)

Frog51




Frog51

Unfortunate Mistake (2)

frog51 (51816) | more than 13 years ago | (#998590)

Unfortunately, the 802.11 Frequency Hopping standard does not allow the device to learn which parts of the frequency range are interfered with. It would be nice, but it just can't happen, as it would screw up so many other parts of the standard.

Sorry to disappoint

Frog51




Frog51

Re:This is only the beginning (2)

edunbar93 (141167) | more than 13 years ago | (#998591)

Yes but you dont need to induce the power into the enginge. Mess up the controls and you could get a freghttrain to run amok. It has been done with planes ( cellphones, you know the rest ) Perhaps you should enlighten us? How exactly _did_ such a low-power radio such as a cell phone mess up the _controls_ of an aircraft? No, you are horribly and woefully misinformed. (or you completely lack understanding in this area, in which case you shouldn't say anything) What happens with cell phones and aircraft has nothing to do with the controls, but the navigational equipment that recieves radio signals. Since these devices are likely to overlap in the frequencies they use, it's not such a huge leap of logic as to why such navigational equipment might not be very accurate under these circumstances. It's also worth noting that freight trains do not need radio navigation equipment to find their way. You shouldent underestimate the strangeness of things that can happen when dealing with HFEM radiation. Riiiiiiight. Seen any funny lights in the sky lately?
---

Re:* Warning * (1)

acvh (120205) | more than 13 years ago | (#998592)

attribution should go to Monty Python for the original of this post.

Re:Ah yes... But...... (2)

danderson (157560) | more than 13 years ago | (#998593)

And on most wireless phones and LANs there's only ONE preset frequency, and since it's neatly set at EXACTLY 2.4 GHz, ofcourse they'll interfere...

I don't know about wireless phones, but wireless LANs (at least 802.11b) usually have the option of 11 frequencies in the 2.4GHz band in the US. Other areas of the world have different restrictions. Usually a 5 channel separation will eliminate interference from other 803.11b devices, so if you are using channel 6 and your neighbor is using channel 1 and your other neighbor is using channel 11 their shouldn't be a problem.

Overloading base station with users (2)

frog51 (51816) | more than 13 years ago | (#998594)

This generally shouldn't become an issue, as the 802.11 standard allows for intelligent loadsharing (assuming rf coverage by more than one AP).
Certainly, we like to overlap quite heavily in industrial areas - continuous coverage by 3 AP's for any mobile device pretty much guarantees robustness (for hw fail or congestion) - of course using Voice over IP over 802.11 rf does mean we need nice fast routers in there as well:)

Frog51




Frog51

Problem, A440 (1)

thesparkle (174382) | more than 13 years ago | (#998595)

Sounds like the explaination for our problem at home with our wireless cards. We randomly drop signal from one of our laptops in different parts of the house, that is after it has been working fine for 30 or 40 minutes.

I used to sell guitars in a large store when I used to live in Dallas. You could not use a wireless, electronic tuner to tune them because the overhead flourecent lights put out 440MHz which is an "A". Or so said the other guys who worked there. I just wanted to jam.. :)

Phones (2)

Dungeon Dweller (134014) | more than 13 years ago | (#998596)

Well, the phones have a whole stack of problems in their own right. First, any idiot can tune in to them (no encryption). Second, they interfere with each other a lot. You're not likely to notice the second, unless you live in between a college dorm and a college sorority, like I do (thank you God). At any rate, I'll keep the 802.11, and I'll keep the phone, since nobody really cares what I am getting on my pizza.

Re:Commercial radio vs. my cellphone (1)

edunbar93 (141167) | more than 13 years ago | (#998597)

Sure. If your nervous system were made out of copper wire... Is it?
---

Re:* Warning * (2)

Hard_Code (49548) | more than 13 years ago | (#998598)

Man, first its kids getting all hopped up on "Placebo", now this "Wireless" stuff!? When will the madness end?!

anyone suprised? Yes me, read why. (1)

NKJensen (51126) | more than 13 years ago | (#998615)

In the RC days, you had to select frequency by crystal selection.

The license free devices have similar ways to get their data sent - they do frequency hopping, direct sequence, etc. Please read the other replies about this.

The old RC gear at one frequency is just not a valid comparison to modern 2.4GHz devices.

Ethernet cookery? (1)

Anonymous Coward | more than 13 years ago | (#998616)

2.4GHz? Hmmm, and microwave cookers use 2.45GHz. Imagine having a whacking great free-running oscillator, drifting with temperature, right next door to your ethernet...
Any spec on what happens to your network when you nuke your coffee? Cheers,
Gordonjcp

Re:This is only the beginning (1)

Lion-O (81320) | more than 13 years ago | (#998617)

I see you didn't take my advice. Grow a clue and either follow my advice or read up on the technical details. I've seen this happen with my own eyes and at a later stage was also able to explain what happened due to my technical studies.

Re:This is only the beginning (1)

]ix[ (32472) | more than 13 years ago | (#998618)

Yes but you dont need to induce the power into the enginge. Mess up the controls and you could get a freghttrain to run amok. It has been done with planes ( cellphones, you know the rest )

You shouldent underestimate the strangeness of things that can happen when dealing with HFEM radiation.

Re:This is only the beginning (1)

]ix[ (32472) | more than 13 years ago | (#998620)

Riiiiiiight. Seen any funny lights in the sky lately?

I just have to put my old nokia 8110 next to my Sun ultra1 to witness some really flaky stuff. And since I am taking an astronomy class This summer: Yes I have seen some funny lights in the sky lately, A couple of kvasars and an close flyby of an small asteroid, anything else?

Wenn I said controls I ment control system or electronics or whatever you want to call it.

In A modern train by ABB [www.abb.se] all the redundant electronic subsustems (ALL) are bit-inverted from their counterparts so that they wont suffer the same from interference.

I used to work at an small airport here in sweden when one of the pilots told me an amusing story of a buissniesman who when he rebooted his laptop made the autopilot turn. No wavelan and no GSM was involved.

Strange... (1)

suwalski (176418) | more than 13 years ago | (#998621)

I think this whole situation is strange. In North America, three types of cell phones operate on the same frequency. They are:

GSM @ 1900 MHz

CDMA @ 1900 MHz

TDMA @ 1900 MHz

I have a GSM phone, and I have friends with CDMA and TDMA phones, all at the same frequency. We can be in a room together and I notice no interference, although the only real difference between the phones is their software/protocol/codec.

So, do thew rules change at 2400 MHz? Do devices interfere just because they're at the same frequency? Are sloppy codecs involved? Are the protocols messy?

Questions, questions, questions...

2.4GHz frequencies interfere with your brain. (2)

roman_mir (125474) | more than 13 years ago | (#998622)

Actually all frequencies can interfere and resonate with your various body parts. It has being established that in experiments with rats and mice frequencies on which US cell phones operate cause the rodents to develop disorientation and worsens their further learning abilities. Of-course rats and mice are not people but in some respect mice are the closest human cousines, they have the DNA closest to the humans (after the primates of-course). So it's not only your wireless network that is suffering, it could well be your wireless brain too.

Re:isn't this... (1)

Rabenwolf (155378) | more than 13 years ago | (#998624)

... the band range the licenses for which the German government is about to auction off with an expected profit of $50,000,000,000 ?

Close, but not it. UMTS operates between 1.885 and 2.2 GHz.

The spectrum for UMTS has been identified as frequency bands 1885-2025 MHz for future IMT-2000 systems, and 1980-2010 MHz and 2170-2200 MHz for the satellite portion of UMTS systems.
- whatis.com [whatis.com]

Re:This is only the beginning (1)

Lion-O (81320) | more than 13 years ago | (#998625)

Then explain to me the result of one of the investigations into alien sightings; They found out that a lot, if not most, of the alien sightings in the US (I guess it also goes for other countries) happen to people living close to electrical power cables.

After more research they discovered that the 'radiation' did indeed affect the human brain and were also capable of reproducing this phenomenon by subjecting people to a certain amount of "radiation" which was created by high voltage electrical coils.

I don't have an url anymore since this research happened allready some time ago but I'm quite sure that anyone capable of using a search engine should be able to track this down again.

btw; out of curiousity, you wouldn't happen to work for some GSM network provider?

This is only the beginning (3)

Lion-O (81320) | more than 13 years ago | (#998626)

And I'm not just talking about one device influencing the other here. I'm also very concerned where human health is concerned. There are so many different frequencies being used and we hardly know anything about the real effect it has. And to be honost; this article is only the top of the iceberg.

I'm from Holland and like in every country we also got out television and radio stations, next to a line up of GSM networks. All of these have transmitters. The GSM's have small antenna's which are spreak among the country but the television and radio have one big antenna which allmost covers the entire country. And here the fun part begins.... People living there are having extremely difficult times in buying electrical equipment. Why? Because it hardly works and or acts extremely funny. And I'm not talking about weirdness like we all know from Windows. No; this is serious stuff. Like electronic stoves going crazy (hot / cold), microwaves which act crazy or not at all for no reason what so ever, electric trains which run out of their own; a copper wire is more then efficient. Things are so bad that most people just can't use any electrical devices such as computers; they don't work as it should. Things are so extreme that local re-sellers are refusing to sell these people electrical equipment since they keep claiming due to problems.

So basicly this article doesn't come as a surprise to me. There is more going on then people know, and all the radio waves out there are doing something. IMHO even more then most people realize.

But what is the alternative? (1)

Digitalia (127982) | more than 13 years ago | (#998630)

I honestly think that high frequency device communications will only develop well, without government interference. Once all of the protocols and devices have been developed thourohghly, then let the FCC or whomever take over. Interference of radio waves or interference of capitalistic government. Thats what I thought.

This is a known problem (5)

frog51 (51816) | more than 13 years ago | (#998635)

I install 802.11 networks by Symbol, Lucent and Telxon (Aironet/Cisco) and this is something I come into contact with more and more.
Frequency Hopping (FH) devices tend to kill the reception by Direct Sequence (DS) devices, mainly due to the differences in signal strength. Multiple DS networks can happily coexist, and run at 1,2,5,11 or 25 MBit/s while keeping the actual signal at below ambient noise strength (nice - security-wise)
FH networks just tend to upset all other 802.11 networks, and they only go up to 2 Mbit/s at the moment. The reason people use them is that they are very stable and solid. They just work, without tweaking!

With todays bandwidth demands, you have to go for the 25 Mbit/s gear (which gives you throughput roughly equivalent to a 40Mbit/s ethernet type protocol - due to use of CSMA/CA not CSMA/CD) so things should get better as more people use DS not FH:)

Frog51



Frog51

Re:This is only the beginning (1)

Digitalia (127982) | more than 13 years ago | (#998636)

Good god! Air pollution and water pollution used to be our only problems. Then we had to cope with light pollution. Now the world is becoming inundated with the rest of the EM spectrum. I used to fear the destruction of the environment. Now I fear that, and the eventual digital apocalypse. It would end the problem, but how would the people cope?

Commercial radio vs. my cellphone (2)

seldolivaw (179178) | more than 13 years ago | (#998638)

I'd be interested to know if anybody can figure out why my cellphone causes extremely loud, audio interference on a variety of appliances -- my TV, my radio, and even my laptop speakers. I live in the UK, and I'm pretty sure my cellphone isn't operating on the same wavelength as my radio and my TV. I know that cellphones broadcast unusually powerful signals in the UK (3 or 5 times greater than the rest of Europe) -- could the sheer strength of the signal be causing resonance with all these speakers? The signal is a very strange, repetitive clacking noise that sounds like it's searching -- it gets louder, then my cellphone registers a call or a message, then it fades away again.

I'm really mystified by the cause, I'd appreciate anybody who know what the 'cause is because I really do worry about my brain getting fried by these things.

Re:isn't this... (1)

jarkko (40871) | more than 13 years ago | (#998639)

Probably not. Unless I'm very mistaken they're auctioning the licenses for 3rd generation GSM (gprs/umts whatever) to operators. England got a shitload of money doing that. Basically the cost of obtaining the license tricles down to the consumer, which is why I'm happy that Finland won't be auctioning them (the calls are expensive anyway.)

As mentioned on other posts the 2.4GHz range is free to use (unlicensed) for low power devices.

You can overcome interference by using more power (1)

Anonymous Coward | more than 13 years ago | (#998642)

Go here [dct.com] for more info.

Re:This is only the beginning (1)

edunbar93 (141167) | more than 13 years ago | (#998646)

Wow. There sure are a lot of moderators who moonlight as conspiracy theorists. 4:Interesting? More like 0:Flamebait.

This guy needs a reality check. The only place in the universe that one is safe from those darn Electromagnetic Radiations is deep underground. (And where it's very cold indeed... heat is of course a form of EM radiation.) Except for all those damn neutrinos that might accidentally pass through a cell or two of course, breaking his DNA someplace funny and causing cancer. Even without human intervention, we're constantly being blasted with EM radiation from places like the Sun, the Milky Way, and about a billion billion other stars and galaxies.

I just love environmentalist twits who think they're smart by talking about something they clearly know less than nothing about. It seems the only thing that gets them out of bed in the morning (for fear of all the things that are hazardous to their health) is the idea that they can make the world so much safer by getting the government to pass laws against sunshine.
---

Re:This is a known problem (1)

_ganja_ (179968) | more than 13 years ago | (#998647)

I want to connect my 3 PCs at home via wireless, two PIII workstations and one laptop, can you recommend a product?

Re:This is only the beginning (1)

zmooc (33175) | more than 13 years ago | (#998648)

Maybe if you use an electrical relais-like device to switch the train on and off, it'll work; there's a lot less power required to make simple electronics `do' something... By the way...you know the sounds speakers make when a cellphone is nearby...there must go a rather large current through them to do that...I guess such current is waaaay enough to make electrical devices do really weird things.

Re:Poor Receiver Design? (2)

frog51 (51816) | more than 13 years ago | (#998649)

Actually, the DS receiver design is pretty good - DS uses a large chipping algorithm which effectively smears the signal from a high, narrow-band to a low, wide-band. A receiver using the wrong chipping algorithm just further smears the signal, but one on the same algorithm rebuilds the signal back to a peak and flattens all noise/extraneous signals - as best it can.
What seems to be happening is that the FH transmissions are just far too high a noise level for the DS receiver to cope with!

In the UK the signal strengths are so low (100mW) that this is very localised - adjacent buildings act as individual cells, but the US has more of a problem as they are allowed 1W output power.
Don't fry your brain cells, guys!

Frog51




Frog51

802.11b (2)

Kishar (83244) | more than 13 years ago | (#998650)

Well, he gives us the answer in his article.
In the 802.11b (the b is important) standard, he's using DSSS (Direct Sequence Spread Spectrum) radios as opposed to frequency hopping. This means he's able to get up to 11Mbps per device, but, it also means only 3 non-overlapping channels. While there are many channels (11 or 12, IIRC) in the 2.4GHz range, the DSSS 11Mbps radios lump multiple channels together (802.11 radios were 2Mbps because they only used one channel instead of groups of channels). Now, toss the Seimens Gigaset (which is also Spread Spectrum, I believe) and other wireless devices into the mix and ... well, one can understand why there's just not enough of the bandwidth left. Just like with the 900MHz range, 2.4GHz is in the ISM band (Industry, Science, and Medical), the two options at this point are: change the 802.11b devices to 5.7GHz devices, or stick with 900MHz for the appliances to free up the 2.4 for the NICs.

Just my thoughts.

Re:Commercial radio vs. my cellphone (1)

Steeltoe (98226) | more than 13 years ago | (#998651)

If this happens inside electronic equipment, wouldn't the same thing happen inside our brain and nerve-system?

- Steeltoe

Re:This is only the beginning (1)

Felinoid (16872) | more than 13 years ago | (#998652)

Before people act to rash to this guy (or take him to sereously) [Mod 5? and assult replys.. gezz]
This isn't really a new problem.

In the days of radio someone built a radio station that could broudcast around the United States. Wonderful hmmm?
It worked... but everyone living in the area had to suffer. The signal was messing with everything electronic.
Thats when the United States FCC stepped in and said "no signal stronger than X" and thats the law today. Problem solved.

I suspect your nation may simply be allowing everyone to transmit extreamly strong signals.
We are very clear on what radio waves and microwaves can do. Thats how we get radar and microwave ovens. How we also get radios powered by the radio signal and some of the LAN technologys that came up in the 1980s.
It's also why people talk of EMP (if drops a nuke the resulting EMP will distrupt anything electronic for miles.. whipe HDs etc).

Holland is starting to get some note over in the United States for a LACK of burocratic mentality. I don't know if this is reality or pure myth however so I won't talk about it :)
Even if it is a myth this at least shows the type of thing that generated it.

This isn't a lasting problem. Just get the fedral communications burrocrats to do something reasonable with the signal strigth.

Problem solved....
(Strong EM signal will damage microchips. But thats some pritty nasty stuff... not something most people would deal with)

Easy home WLAN (1)

frog51 (51816) | more than 13 years ago | (#998653)

3 Com are currently running a deal (in the UK, anyway - probably is similar in US) for 2Mbit/s Access Point and 3 ISA or PCMCIA cards for £800. Translate to US - translate to $ (usually works that way!) means a happy home WLAN for $800. Their kit is rebadged Symbol FH gear

I have run Quake 2 over an 11Mbit DS Aironet WLAN with 4 players and it was as good as my ethernet, even though one of the guys was a couple of km away (directional antenna for him)

If you are grabbing vast database files then it won't be happy, but it copes with most home user stuff:)

Frog51




Frog51

Re:This is only the beginning (2)

dattaway (3088) | more than 13 years ago | (#998654)

Speaking of making light bulbs glow, we used to have this problem in our cars when CB radio was popular among my peer group. The car of a friend would suddenly die when keying down the microphone. Mine had lights that weren't even connected to the battery anymore, such as what went to old fog lights, would light up when keying down.

OK, so I had a 150 watt amplifier. It also caused problems with phones and television in the vicinity, but it was nothing compared to the problems a friend of mine who had a 500 watt Tram amplifier connected to a beam antenna. He demonstrated how his radio got into cable television broadcasts.

So those were a bit more than one watt, but we had a crazy idea of making our own 10GHz 1KW coffee heater installed in our front bumpers. Most people who have radar detectors would know the other use of that one.

Re:Commercial radio vs. my cellphone (1)

jhein (194635) | more than 13 years ago | (#998655)

I am a Ham operator, and I have caused problems in a TV's surround sound system even at 1W power. What you need to do is keep the AC signal that's being picked up by the wires from being rectified in the equipment itself. You *might* get away with using a ferrite bead for low power, however I typically use a 1pF (any will do, the smaller the better since the formula is 1/(2*Pi*R*C)) ceramic capacitor and put it across the speaker terminals. Audio passes fine, but HF and above get shorted to ground. I have tested this on my TV with up to 1KW, though I usually run at 100W on HF.

Re:This is only the beginning (1)

yuggoth (85136) | more than 13 years ago | (#998656)

The light bulb I was talking about was an ordinary 220 Volts / 20 Watts bulb. I admit that you would have to live very close to the station to have your trains running by themselves, but if it broadcasts in the kW power range, I think there should be enough power arriving at your house just through the air. Of coure, it still could be an urban legend...:-)

Re:This is a known problem (1)

KmArT (1109) | more than 13 years ago | (#998657)

DS doesn't interfere with FH because FH will just work around the jammed channels that DS is using. However, with DS, if someone is FH on your channels, you're SOL. DS vendors try to paint the problem as being with FH but that really isn't the case. With FH, you have to jam 26 channels to block a signal. With DS, you have to jam a few channels in one of the three sequences and you can jam the whole sequence. I've seen this problem coming for about two years, ever since I had my first wireless networking course. The sad thing is, as litigious a society as we live in, some lawyers will probably get rich off of interference. As I understand it, microwaves (the kind you cook food in) also operate in the 2.4Ghz range, as does some TV feeds (i.e. when the truck is out on location for breaking news and sending info back to the main station). As 2.4Ghz becomes more and more populated with bunches of different equipment, vendors have (and already are) making the leap to the next free band, the 5.8Ghz band. Witness the evolution of wireless phones. I'm not sure what the cheapie ones run at but you have 900Mhz, now 2.4Ghz, guess where the next ones will be? 5.8Ghz (along with all the other wireless devices that migrated there to get away from the congestion in the 2.4Ghz band :)

Re:Phones (3)

sde1000 (10806) | more than 13 years ago | (#998658)

Well, the phones have a whole stack of problems in their own right. First, any idiot can tune in to them (no encryption). Second, they interfere with each other a lot.

Not true, at least for DECT phones like the Siemens phone mentioned in the article. First of all, DECT is a frequency-agile standard (the handset continuously monitors the signal from the base station, and can initiate a handoff to another frequency/time slot or basestation if the quality drops too low). Second, the DECT standard defines authentication and encryption algorithms which are supposed to be supported by all DECT-compatible equipment.

Unfortunately, like all other ETSI encryption standards these are not publicly available, and as far as I know there has been no effort put into cryptanalysing them. If they are anything like other ETSI-sourced algorithms (for example those in use in the GSM system) they are probably full of holes.

Interestingly, Siemens claim to have implemented their own encryption algorithm in their GigaSet range of products, but since they don't publish the details they have exactly the same problem...

Re:Easy home WLAN (2)

hey! (33014) | more than 13 years ago | (#998659)

For home use, you can save major dough by skipping the access point and using peer to peer ("ad hoc"). Cost is about $80 per node for 2MB access using the webGear aviator 2.4Ghz card, including two ISA PCMCIA adapters. The webgear aviator card is a relabelled raytheon raylink card, so you can get the "professional" features (mainly the ability to access an access point) by downloading the raytheon drivers for Windows.

The raylink drivers are also included in the all the recent Linux PCMCIA subsystems, as well as the Lucent WaveLan cards (much faster, shorter range); don't download any "drivers" from the WebGear site, they're stale. Under Linux, the card works like a charm, far better than under windows; I can pop the card in or out as necessary without my system hiccupping, whereas Windows tends to hang.

In any case, I can roam around the house or out into the backyard with no problem. I used it to share an Internet connection with our kitchen computer because for $160 bucks for a pair, it was well worth avoiding the hassle of pulling cable, and 2Mb/sec is plenty fast.

Re:This is only the beginning (1)

ocelotbob (173602) | more than 13 years ago | (#998660)

Same thing is happening to a neighborhood near where I live. An average sized (6000 watts) AM radio station is reeking havok with a neighborhoods electronic devices because of all the interference its putting off. TVs, VCRs and computers will play Korean music out of the speakers, the picture will be nonexistant, and the people have to buy some pretty heavy duty shielding in order to have their items halfway useable. I'd love to post a link to the news article, but the only paper that has the story is not yet on the internet, so, neither is the story.

Ah yes... But...... (2)

Anonymous Coward | more than 13 years ago | (#998661)

Ofcourse this is expected to cause problems... What's concerning me is, as the article proposes, that the manufacturers do not seem concerned about this. In the old days when You bought an open fequency "commodity" (anything really), You could usually "tune" the set to a slightly lower or higher fequency (as You changed Your crystals). This option seems to be gone from most equipment You buy today. I tested a Wireless Video/Audio transmitter set, and it only had TWO settings for frequencies ! Suppose both my neighbors had the same set ? And on most wireless phones and LANs there's only ONE preset frequency, and since it's neatly set at EXACTLY 2.4 GHz, ofcourse they'll interfere... So what are we supposed to do ? Shield the transmitter and reciever in a cage ? Might as well go back to wires then.
No this is DEFINATELY up to the manufacturers to work out. if they want to sell their crap to us. They better make sure it works.

* Warning * (5)

Jon Peterson (1443) | more than 13 years ago | (#998662)

If you have any combination of cordless phones, wireless ethernet, wireless video, or Bluetooth you could be having problems. Not only will your bank balance will be suffering a from the debhilitating effects of continuous expenditure on unecessary geeky networking technologies, but your health will be in sever danger.

An article to be published in the Lancet later this month will show how people can suffer serious side effects from replacing all the cables in their house.

"It started happening after I went to one of those underground Linux install parties" reports a young man, who we'll call 'Alf'.

"At first, it was just phones. You know, people passing around some Nokia's and Ericssons, and it felt really good to be cordless. It was like I was with the in-crowd."

"After a few weeks though, people started getting out the infra-red enabled PDAs out. I didn't think anything of it at the time."

But, as the report shows, cordlessness is an unpleasant and addictive activity, and it's only a matter of time before the serious health implications start. 'Ben' has been in re-hab for three months now, getting used to staying in the same place when he talks on the phone, and being re-trained in Cat5 cabling.

"I can't remember much towards the end" says Ben, "I was really out of it. There was like about 4 of us in this house in Shoreditch, you know with serious 802.11b right through. It was like a permanent trip. We used to have these wild parties at weekends with loads of girls and booze, it was pretty wild, people doing it with like Psion5's and i-mode phones, really f**cked up stuff."

But although Ben is recovering, it's a growing problem thoughout London and the whole of the West. Dissatisfied with their parents' strict ideas of free love, home grown dope, and long skirts, the young generation are turning to hardcore wireless technologies, with street names such as Bluetooth, WAP and i-mode.

Next: The Goverment launches "War on Wireless" to stop this disturbing trend in our young people.

Regulations in the 2.4GHz band (4)

skion_filrod (201359) | more than 13 years ago | (#998663)

This is interesting: although the 2.4GHz band is "unlicensed" it doesn't mean there is no regulation. For example, in Europe all 2.4 GHz equipment has to fulfill certain regulations derived by ETSI (European Telecomunications Standards Institute):

  • ETS 300 328
  • ETS 300 826
The later standard is used for Bluetooth applications; from what I understand all equipment must abide to ETS 3090 328.

The fact that the Siemens Gigaset and X10 are noisy could be that the ETSI standards actually allows them to do prett much what they want to; it could also be the case of bad design of the X10 or Gigaset equipment. I have seen plenty of cases where equipment from wellknown manufacturers claims to be approved according to CE emissions standards (EN55022/23), but when measured up proves to be way of.

Regarding Bluetooth, it is my understanding (after working with it for one year from a hardware designer perspective) that BT is designed to work in "noisy" environments. BTs frequency jumping scheme is designed to make the most of the frequency band, even if there are cordless phones and wireless LANs using the spectrum also.
Also, BT is a low power technique in contrast to IEE802.11 and possibly the cordless telephones.
I have followed some threads regarding possible interference between IEEE802.11 and BT, and the latest information is that they do not interfere and thus can coexist.

Standard disclaimer: I may be wrong :-)

FUD alert (5)

adolf (21054) | more than 13 years ago | (#998664)

The author of the linked article is obviously inadept at grasping the reality of what he was witnessing.

The 802.11 cards and Siemens phone system are frequency-hopping. By switching frequencies often, they reduce overall interference at the expense of a little bandwidth (there's plenty of room at 2.4GHz for these things to co-exist). Some types of frequency-hopping "spread spectrum" devices will dynamically learn trouble-spots and avoid them, bringing bandwidth back up to a point approaching ideal (unless that entire block of spectrum is completely hosed).

So, the phone system and wirelss LAN should work fine together. There will be a slight (measurable, but imperceptable) decrease in bandwidth for the LAN while phones are in use. The phones, if they're poorly designed and/or the CODEC is intolerant of errors, may suffer an occasional (and very brief) dropouts; due to the real-time streamed nature of the device, retransmissions aren't possible as they are with 802.11. I don't suspect these dropouts would be overly bothersome, or even noticable in most instances.

Interestingly, the X10 video-sender box was the last thing he threw away. Oddly enough, that's the device which should have gone away *first*. It's cheap - too cheap to use any of the present-day bandwidth-reducing digital coolness of most other 2.4GHz devices. So, it spews forth broadband analog video - likely using *more* bandwidth than a TV station to avoid expensive modulation/demodulation parts - destroying the 2.4GHz for the rest of the household toys. Remember the remark above about the spectrum being completely hosed? This is probably a better example of an RF monster than anything else available to a consumer today.

Had he turned off the bargain-bin X10 stuff first, I strongly suspect he would have had no further difficulty (and would continue to enjoy the hideously-cool phone system).

That all said, I really don't see the need for moving to 2.4GHZ for *everything*. It offers more bandwidth for a given slice of spectrum, which is nice - and really not needed for things like telephones. I prefer to get my cancer from tobacco, standing too close to the microwave, and hanging out by 600,000 volt transmission lines - not talking on the phone.

Re:This is only the beginning (1)

Felinoid (16872) | more than 13 years ago | (#998669)

Now there is reason and there is paranoia.
Today is aliens. A long time ago it was monsters (vampires etc) in the future it'll be the "unknown effects" of radio signals.

If you are sereously having a problem the cause is overpowering signal...
(BTW the nuro-electric brain is not anywhere near as suseptable to interfearence as electronics...)
What is GSM power? If someone is providing power vea radio waves this may be your problem. To provide enough power to do anything you'd have to give a strong sigal... Thats house current flowing throught everything electronic... That'll fry a microchip really easly..

Again.. you sound paranoid... Your debate tactics belong to the flat earth socity...
A lot of people have seen UFOs... and a lot of people have seen vampires...
I see a monster every morning when I wake up and look in the mirror.. a horrid looking one...

Re:Easy home WLAN (1)

_ganja_ (179968) | more than 13 years ago | (#998671)

The DS Aironet seem like like the kinda thing I'm after 11Mbit is a lot less limiting than 2Mbit and I guess DS is better than FH?? The Aironet seem to have Linux support as well but didn't Cisco buy them? Maybe that might make them hard to find?

Any ideas where I can buy them, I'm in Holland but ordering from the UK is fine. I need 2 x PCI and 1 PCMCIA.

Re:This is only the beginning (1)

Schnedt McWapt (195938) | more than 13 years ago | (#998673)

In fact, he told us that for some time, this was a cheap albeit illegal way for people to light up their garden sheds near a TV transmitter station in the first years of broadcasting.

Why would it be illegal? It seems like a very passive method, which doesn't radiate any interference at all. I've thought for quite some time that people living near broadcast towers should be able to soak up as much of anything that radiates from said towers with impunity, so long as they radiate nothing. Hell, they just have an efficient antenna. If the broadcaster doesn't like it, they can move.

The fixed chart. (1)

Anomalous Canard (137695) | more than 13 years ago | (#998674)


|
|............---7---
|..........---6---
|........---5---
|......---4---........---11---
|....---3---........---10---
|..--2---.........---9---
|---1---........---8---
+---------------------------------------------
frequency ----->


Hint: Use the <tt> tag.

Here's a fixed version of the chart. I hopt that this is enough text to pass the lameness filter. Isn't that lame -- having to add lame text to bypass the lameness filter.

Anomalous: inconsistent with or deviating from what is usual, normal, or expected

Um, this is not that hard to solve, ya know? (2)

Randy Rathbun (18851) | more than 13 years ago | (#998676)

These problems are no different than when you go to Radio Shack and buy some of their radio controlled toys. The toys are plainly marked what frequency they run on. If you get two cars that are on the same frequency and try to run them at the same time, of course they are gonna go wacky!

We are going to see more and more devices up at 2.4 GHz. What is the solution? Quit it! It is that simple.

These same problems everyone is gritching about is how it was with the early 49 MHz phones. Someone would get one then their neighbor would get one and they would inevitably take them back to the store because "they were broken". Well, sorry, but they are not broken, it is just that someone else is on that frequency also.

Look around your house and check out how many wireless devices you have. Do you need 3 cordless phones? Do you need wireless TV transmitters and ethernet cards too? Yeah, they are nice, but when you start getting interference between them, well, I hate to say it, but there is only one person you can blame for it.

Re:This is only the beginning (1)

pe1rxq (141710) | more than 13 years ago | (#998680)

Still not very likely since if fifty people would be able to light such a light bulb nobody would receive anything since all power goes to the bulbs.
Get the point???? It will be almost impossible to 'catch' all that power
Jeroen

WaveLan and Microwaves don't mix (1)

Smurphy (26684) | more than 13 years ago | (#998681)

I've noticed that when my microwave is on, my
WaveLan latency goes way up. I guess I have
a nice 2.4Gz microwave.

Re:This is only the beginning (1)

amsel (178807) | more than 13 years ago | (#998682)

but if it broadcasts in the kW power range, I think there should be enough power arriving at your house just through the air.

Hmm, I dunno. Suppose it goes out spherically (I know, it's lobed, but just to estimate) so the power per unit area goes down with the distance squared. You'd only have to go, say, 100 meters to get a a 10kW/m2 power density to 1 W/m2. So you could maybe get a small glow if you lived next door, but surely this is why we need amplifiers, and power lines for that matter?

Re:This is only the beginning (1)

Schnedt McWapt (195938) | more than 13 years ago | (#998683)

In the early days of radar, there are cases of Navy personnel being literally cooked by the beam.

Re:Ah yes... But...... (1)

pe1rxq (141710) | more than 13 years ago | (#998684)

Actually it is not up to the manufacturers since they cannot choose the frequency band which will be available and on 2.4 Ghz there are different channels. BTW do you know where microwave ovens operate? 2.45 GHz... Jeroen

Re:Commercial radio vs. my cellphone (1)

Vanders (110092) | more than 13 years ago | (#998685)

Yup, i've noticed that one too. I've also noticed a "buzz" on my TV when someone is using a mobile near it (Even say in the room next door). It is slightly worrying, when it comes to things like my computer (And health too).

Cooking with interference... (1)

farqwart (196874) | more than 13 years ago | (#998686)

I don't know whether I'm remembering this correctly, but don't microwave ovens cook using some in the 2.4 GHz range? Given, they should be sufficently shielded, though who is really going trust their frag count to should. I guess I'll have to make a sign that says "No Microwave use, Quake match in progress..."

Re:Commercial radio vs. my cellphone (3)

Beta (31442) | more than 13 years ago | (#998687)

The radio signals induce currents in the wires inside your TV/radio/whatever. The currents are rectified by any active semiconductor (transistor, ic, whatever) and the resulting signal has frequencies all over the spectrum. So your nice 900MHz GSM signal gets transferred to audio spectrum. This "artifact" is used in primitve AM receivers to convert the filtered (just the channel you're listening to) high frequency signal to an audio frequency signal.

The reason older analog cellular phones don't do this is that they send a continuous but relatively low power signal. Digital phones send bursts of high power signal so audio electronics picks it up a lot easier. The average power over time is about same for analog and digital phones tho.

Re:This is only the beginning (1)

pe1rxq (141710) | more than 13 years ago | (#998688)

No, just a second whack on the head to make him rational again (Hey it works in cartoons...)
Jeroen

Re:Commercial radio vs. my cellphone (1)

Monokeros (200892) | more than 13 years ago | (#998689)

I live in the US so I don't know about having unusually powerful signals. However my Ericson (maybe thats why) has two noticable EM interferance symptoms.
1) about every 10 minutes my pc speakers click twice in rapid succession when my phone checks for voice-mail
2) right before I get a call my pc speakers click, buzz with ascending loudness untill it becomes almost unbearable (no matter what the volume is turned to) and then stops as soon as the phone rings. And if the phone is close enough to a monitor or two the image becomes purple and wavy. its pretty.
This is very convenient for confusing the crap out of callers. "How the crap did you answer so fast???"

Interestingly, there is a large tv in the next room and whenever it is turned on the automatic degaussing feature causes a fairly similar effect on my monitor as the phone.
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