How to Avoid Mobile Phone Interference w/ Speakers 228
EnzoTen asks: "Everyone has been sitting at their desk rockin, jamming, or groovin to their favorite tunes. You are in a trance, getting work done... then... BZZZPT... BZZTP..BTT.. BZZZZZZZZPTT... the blood curdling noise of your cell phone interferes with your desktop speakers playing 4 times the volume of your music and it takes everything in you not to flip your desk upside down, or throw your mobile phone across the room. Is there anyway to avoid mobile phones interfering with speakers? Are there speakers available that are shielded from this type of interference?"
Ya (Score:2)
When I'm in the car, I dont put my phone in the phone holder anymore, I put it on the seat next to me.
Also dont put it next to your alarm clock, thats a bitch to be woken up to that BZZZT screech.
Simple (Score:2, Informative)
Re:Simple (Score:2)
Re:Simple (Score:4, Funny)
Re:Simple (Score:5, Funny)
Symptom: When you use X, Y doesn't work properly.
Cause: Due to a design deficiency in X, Y sucks when used in conjunction with X.
Solutions:
Re:Simple (Score:2)
Of course, when you work for Microsoft, the problems are often lame, the solutions often don't exist, and the workarounds ofte
Re:Simple (Score:3, Insightful)
Re:Simple (Score:2)
Re:No no no!!! (Score:2)
Re:Simple (Score:2)
What providers are you using? What phone?
Re:Simple (Score:2)
Informative?
Because Slashdot doesn't have a +1 Obvious" mod.
Wait, what? (Score:2)
What model phone/speakers do you use? I'll have to remember to avoid them.
Re:Wait, what? (Score:3, Interesting)
The interference is a clicking, somewhat like a rotary phone (I now feel old). It happens when the phone is talking to the tower. I kind of like it as it occurs a second or so before an incoming call starts r
Re:Wait, what? (Score:2)
Nextels do it as well, but the sounds is more like tssh tssh tssh tsssssssh tssh tssh tssh (longer when transmitting voice, shorter when transmitting silence).
On the plus side, you always knew when your phone was about to ring because the buzzing would become more intense and increase in duration.
Re:Wait, what? (Score:2)
Re:Wait, what? (Score:2)
The problem is power amplifiers. You only need a small amount of RF to get on the low level signal lines and bam; it gets amplified. The thing with digital phones is that because they're a pulsed TDM signal there is energy (minimal) right down to DC which gets picked up, "demodulated" and amplified in your power amplifier.
The solution is keep your damned phone away from anything wi
Re:Wait, what? (Score:2)
Re:Wait, what? (Score:2)
Re:Wait, what? (Score:2)
Sheesh. (Score:2, Informative)
Both are the result of either bad or cheap shielding. Most consumer electronic devices should have at least some shielding.
Look for frayed speaker wires. Look for cracks in your cell phone case (the one it's made out of, not the cool "leather" one you got when you bought it).
Either get new speakers, or replace your cell phone. Or both.
Re:Sheesh. (Score:2, Informative)
The issue is shielding--most likely in the wires to your speakers, but potentially in the power cord or the guts of the machine producing the signal out. If there's terrible internal shielding, dirty power or the EMI on the circuit board itself can cause this.
Re: (Score:2)
Re:Sheesh. (Score:2)
GSM (Score:5, Insightful)
The solution is to properly shield the speakers and speaker wire. The speaker wire behaves like an antenna, coupling the signal into the audio amplifier, where it is detected and amplified. It's behaving like a crystal radio, a primitive type of AM radio receiver.
Re:GSM (Score:4, Informative)
See TDMA [wikipedia.org].
Re:GSM (Score:2)
Tus, the current design is GSM-the-protocol over CDMA-the-technique. (Any such phone is likely to be advertised as 3G and does things like real-time video calling.)
(The 3G phones can fall back to GSM over traditional GSM TDMA however.)
Re:GSM (Score:3, Insightful)
I'm 90% positive that the protocol for UMTS has no connection to GSM either.
In short, UMTS is an entirely different standard than GSM, the only thing in common is the name, as UMTS is considered "3G GSM". The protocol is different, and so is the underlying modulation. (In the case of changing to CDMA modulation, you have to change the protocol to take full advantage of the new modulation scheme.)
Re:GSM (Score:2)
They certainly share more than just "name" -- as they both use the same SIM cards, the same network infrastructure (they both use the same
things like "Home Location Register" and phones do transparently go from GSM to UMTS and vice versa in mid-call.)
"UMTS combines the W-CDMA air interface, GSM's M
Re:GSM (Score:3, Interesting)
"In the 900 MHz band the uplink frequency band is 890-915 MHz, and the downlink frequency band is 935-960 MHz. This 25 MHz bandwidth is subdivided into 124 carrier frequency channels, each spaced 200 kHz apart. Time division multiplexing is used to allow eight speech channels per Radio frequency channel. There are eight burst periods grouped into what is called a TDMA frame. The channel data rate is 270.833 kb/s, and the frame duration is 4.615 ms.
The transmission power in the handset is limi
Re:GSM (Score:2)
Options include shielded cable for the speakers and/or ferrite beads to clip around the wiring to squash RF on the line.
The multiplexing scheme shouldn't make a big difference to the interference problem, certainly not compared to the modulation and the frequency. If you're interested in knowing whether GSM uses Time Division Multiple Access to keep users out of each other's way, check the GSM t [radio-electronics.com]
Re:GSM (Score:2)
happens to monitors too (Score:4, Interesting)
the solution, i guess, is simply to use more expensive shielded speakers, since that's what faraday cages do.
Re:happens to monitors too (Score:5, Informative)
Some phones seem to be worse than others. My Treo 600 is notorious for causing problems with CRT's, while lower end phones aren't.
Re:happens to monitors too (Score:2)
mmmm Nextel... (Score:2)
Better cell or more shielding (Score:5, Informative)
#1, get a better cell phone. With TDMA phones (GSM, D-AMPS, iDEN) you get a lot of noise as the transceiver switches on and off several times a second, transmitting at full power. iDEN phones (NexTel) have always been *by far* the worst about this, in my experience. If you get a CDMA phone (eg, Verizon), the phones on a cell share a common, continuous, low-level signal, which does not cause this kind of interference.
#2, shield your amplifier. (In cheap computer speakers, it's built into one of the speakers, or the subwoofer.) Surround it in tin foil, and ground the foil. Other possibilities are poor grounding on the signal wire - replace it with a shielded wire, and ground the shield to your computer's case and where it reaches the amp.
Re:Better cell or more shielding (Score:2)
While I'm there are differences in the amount of audible interference on speakers between th
Re:Better cell or more shielding (Score:2)
If you can't find the amp, you shouldn't attempt this mod. Wrap the tin foil around your head instead.
Buy better speakers (Score:2)
But...I just realized, it never happens at home. I have a set of 5 year old Klipsch 2.1 Speakers, that I would assume have better than normal shielding.
I like it (Score:4, Informative)
It is not just speakers (Score:3, Interesting)
Easy (Score:3, Funny)
Speakers (Score:3, Informative)
My home computer is connected to a reciever that powers separate speakers, I don't really get any problems.
If you were really obsessed, you might get a higher end sound card with balanced audio out, with powered speakers with balanced inputs. If you have cheaper speakers with cheap built-in amps, then the long, unbalanced cable can act as an antenna. I've found that switching to balanced audio connections is the best way to minimize picking up stray noise on the analog, much better than getting "high end" RCA cables. Switching to XLR (balanced) cables drops the amount of noise significantly in just about any analog audio path.
Or you could switch to speakers that have a digital inputs. That's probably a lot cheaper to get into.
I asked this on the Cingular Wireless FAQ wikibook (Score:2)
Turn down your speakers (Score:2)
The speaker buzzing on my system is louder when the speakers are set to a higher volume. Therefore, I have my computer set to output at maximum volume (Wav/PCM and Master channels at 100%) and my speakers are set very low. The result is that there are still buzzes, but they aren't loud enough to give he
GSM isn't a codec (Score:2)
Wireless Router + Amplified Headphones, too (Score:2)
I also have problems with ticking sound on my headphones and speakers, which run through an amplifier (Surround sound headphones). This is directly linked to wireless being enabled on my wireless router. In this case, placing an empty foil snack bag (like a lays chips or quaker rice snacks bag) over the small headphone amplifier box fixed it for me. I guess that the box isn't well shi
Technically.... (Score:5, Informative)
Re:Technically.... (Score:3, Informative)
Very characteristic of GSM (Score:2)
My phone does this... (Score:2)
I have a Nokia 7650 (GSM) that interferes with the speakers whenever it's updating to the towers or a SMS or call is coming in.
I've noticed though that depending on whether or not it's just an update of location, incoming SMS, or actual call, the pattern of the inteference and the volume differs.
I've actually learnt to ignore the location update interference - it's never very loud -, use the SMS interference to let me know without looking that I've got a message waiting, and when the speakers go,
D
Re:My phone does this... (Score:2)
I have a Nokia 6010 and it interferes with my Bose noise-cancelling headphones. [bose.com] Now these are some expensive headphones ($300 SRP) and I honestly think that Mr. Bose ought to have had his people design a cord that would not pick up interference from cell phones for that price.
I also pick up interference from other people's cell phones and blackberry devices as well. While that interference is less than the kind I get from my Nokia in my shirt pocket with the headset cable nearby (or on top), I still hear i
GSM vs. CDMA (Score:2)
Simple solution (Score:2)
2) Do not use mobile phone
Glad to know I'm not the only one! (Score:2, Funny)
1) Keep your phone away from your speakers
2) Buy better shielded speakers
3) Enclose your speakers in a faraday cage and ground the cage
4) Enclose your phone in a faraday cage (note this may make it difficult to dial, oh yeah and it will negatively affect your signal quality too)
5) Get a new phone
Personnally, as s
Better speakers fixed it for me (Score:3, Interesting)
I had this problem at work, where I had some cheap $20 speakers I bought at Office Depot or OfficeMax. The buzzing annoyed me so I took the speakers back and bought some $30 ones. Not too much more expensive, but a huge difference in quality. I still put my cell phone in the usual place, right next to the left speaker, but I've never had the buzzing problem since.
At home I tend to put my cell on my desk next to one of the speakers. The speakers are just a $50 2.1 set I bought a few years ago. They've never done the buzzing thing.
So overall, I have only encountered the problem with cheap speakers. Just a slight upgrade made a huge difference, not just with this problem but in sound quality and general sturdiness. Obviously there are a thousand phone models, and mine is just one of them. I thought I'd put my experience out there at least.
Simple solution (Score:2)
2. Move freakin' phone out of beepedi beep distance.
3. Profit.
Capacitive bypassing (Score:2)
The value ran
An answer from an audio engineer: (Score:4, Informative)
Move the phone away from the speakers (Score:2)
If the phone is a couple feet away on your belt and you still hear interference on the speakers, consider getting a different phone/carrier. Its also pumping that energy into your hip and other nearby sensitive areas.
Harmonic interference (Score:2, Informative)
The cellular signal is rather strong and because of the way it is modulated, it has tons of noise outside its nominal band, almost all the way down to DC. In plain engl
Don't use wireless? (Score:3, Insightful)
I've never experienced radiowave interference on my wired speakers, but know my house (neighborhood?) is nasty on radiowave interference. I tried purchasing some FM-speakers, but they couldn't receive a clean signal
across my living room.
How is your network connection? Wired or wireless? Could it be the network signal being messed with before it hits your computer and you computer just amplifies and echo's out the interference?
I strongly doubt it's in the speaker wires. While I remember a friend of mine in college would play tricks on guys living in the next dorm room, he had a ham radio license and foot long antenna. Still he had to be less than a foot to cause the interference you are talking about -- holding the antenna parallel to the speaker wire that ran along the edge of next door room. Any farther, or disorient the antenna (not parallel to speaker
wire) and there was no interference. He only did a few times when they were cranking music too loud -- they thought it was a problem in their setup, so they stopped cranking it so loud...:-)
However, a cellphone, given it's small antenna and the lower power (his ham setup ~10-30W; modern cellphone: max 3W), it would be hard pressed to generate the same interference.
I'd look to other causes than a cellphone for interference in wired speakers.
However, for 1/8th inch connector thin-wire computer audio, most of the wire I see is shielded. RadioShack sells shielded and unshielded audio cable in lengths up to 20-30 feet. It's not that expensive: less than 20 bucks for a 20 foot extension cord last time I bought some.
Good luck.
-l
Easy. (Score:2)
Built a filter (Score:2)
Ok, seriously...add a little series inductance to the power and audio cables, and some parallel capacitance. You want to allow audio frequencies to pass...but nothing at much higher frequencies. The parallel caps allow high frequency A/C
Re:Never happened... (Score:3, Interesting)
Re:Never happened... (Score:5, Informative)
Re: (Score:3, Informative)
Re:NexTel (Score:2)
Re:NexTel (Score:2)
I believe that in terms of modulation schemes, iDEN is a close relative of GSM, and GSM phones are notorious for these problems.
Re:NexTel (Score:2)
Not that it really matters anyways.... iDen will be gone in about two years. Good riddance...
(I sell T-Mobile, Sprint and Nextel... and I hate Nextel.)
Re:Never happened... (Score:2)
Re:Never happened... (Score:2)
There are numerous other speakers that do this (my mini guitar amp does as well) but it seems that when it gets more expensive, the amplification unit is better shielded and this does not occur.
Re:Never happened... (Score:5, Insightful)
If you do not recognize the problem, it just might be that you
a) do not experience it -> cannot help.
b) do not hear it -> cannot help.
c) notice it, but do not want to help!
In every case, it might have been a good idea to wait and see if more
intelligent and/or helpful people chime in, and might provide an answer to
the riddle. And until that time, just shut up. You probably will just look
foolish if you try otherwise .
I actually *understand* the physics behind that phenomenon, and alas, there
is no better solution than what was provided in another response: put your
cell phone at least one foot away from the speakers. The problem is Maxwell:
in order to send a signal successfully to the next station (remember: this
is most likely indoors, as speakers are less usefull outside, and thus, there
is probably a wall, which has to be penetrated by electromagnetic waves) the
cell phone has to "pump up the volume".
The energy is degrading with the second power of the distance to the cell
phone, so: putting it at double distance to the speaker (or the next
station, for that matter) will lower the received energy by 75%. Same is true
for the station, but that is farther away to begin with.
educating people every day,
Dscho
Re:Never happened... (Score:2)
It really makes me wonder if all those times I've pulled my phone out of my pocket for no reason and had it ring right away were because my body could pick up on the same interference. I also use
Re:Never happened... (Score:2)
We're halfway between two towers, and as an earlier poster said, some days every 10-15 minutes the phone generates interference, probably from switching towers.
Some days, when her phone was near the monitor, the monitor would turn funny colors and have weird lines across it and flicker like CRAZY every once in a while. Solution? Keep phone away. =)
Re:Never happened... (Score:2)
It's so familar here, there was an advert on radio that played this very familar brrrrrtth brth brttttth followed by the traditional, Nokia, beep-beep beep-beep of an incoming text message. Every time you heard it you went to check your phone. Even if your phone wasn't that sort of Nokia.
T
Re:Never happened... (Score:2, Interesting)
If my phone has an active call and I move it near my keyboard, my keyboard stops functioning. Discovered this by chance one day while on hold.
Re:Never happened... (Score:2)
Re:Um...no. (Score:4, Informative)
I have the same experience. It really is very, very annoying.
One of the RF techs at my company apparently modified his computer speakers to filter out the noise. I'd like to find out exactly what it was that he did.
Re:Um...no. (Score:2)
Re:Um...no. (Score:3, Interesting)
Cell phones probably aren't powerful enough to cause cancer, but they sure as hell aren't powerful enough to drive a speaker cone from across the room.
But hey, why listen to me? This article by an electronics engineer [edn.com] was just a quick google search away!
see with most GSM phones and 802.11b transmitters (Score:4, Informative)
What ususlaly catches it is the speaker wires -- they act like giant antennas. 900MHz and up takes only a few centimeters to make a decent antenna, so long speaker cables are a prime target. The high frequncy (which you can't hear) couples on the output lines (typically) and goes back through the gain setting resistors on the amp to rech the amplifier input, where the packet rate (not the 2.4GHz to 900MHz baseband) is rectified and amplified. What you hear is the resulting buzz.
Your cell phone itself doesn't shield this -- then it wouldn't work! The best thing to do is to shield your speakers, wire, and audio system it may be near. A faraday cage (as described by others here) will work great. Plastic-metallic shielding (like that used in anti-static IC or computer part bags) also works wonders.
Re:see with most GSM phones and 802.11b transmitte (Score:2)
Re:see with most GSM phones and 802.11b (Score:2)
Fortunately, there's and even better solution today, which is to keep the signal path digital until the very last moment (inside the speaker), especially optical digital. That'll effectively remove any interfer
Re:Um...no. (Score:5, Informative)
I moved my phone about 17 inches to the right. Worked fine.
Seriously, just move the speakers and phone placement until they don't interfere with each other. A couple decades ago every bit of electronics you bought came with a piece of paper that told you to do this if you got radio or television interference. I always thought it was silly, but maybe that slip of paper needs to go back into boxes.
--
Evan
Depends on the carrier too (Score:2)
Re:Depends on the carrier too (Score:2)
Re:Um...no. (Score:3, Informative)
This definitely does not occur with the CDMA phones that we use (and our company prefers, for other reasons.)
Re:so simple (Score:2)
Re:You've gotta wonder (Score:3, Insightful)
Kidding aside, the worry over cellphones is the damage that might result from the RF energ
Re:Nope (Score:2)
Re:Cheap speakers (Score:2)
Different definition of "expensive," apparently. (Score:2)
That said, the cellphone-interference problem doesn't seem to be related to the type of speakers in use; there are other people in the thread using what I would consider to be high-end equipment and they're still experiencing problems.
FYIW, I don't get this problem in my home system, I only get it in my car. I'll try leaving my GSM phone
Re:GSM ONLY (Score:2)
Re: (Score:2)
Re:please (Score:5, Funny)
What the hell is my phone transmitting when i'm not receiving a call?
It's periodically sending your GPS location to the government who's building a huge database of people's movements, to correlate against all sorts of crimes ranging from terrorist attacks and murders to petty theft and jaywalking.
The RIAA has shown interest in this as well. They want access to the data so they can draw up a list of people who walked by a record store without stepping inside and buying a CD. They claim it's not only in their own interest, but for national security as well, since anyone found guilty of such a crime is a threat to the national economy, and therefore a terrorist. But don't worry, the government is protecting you and is fiercely negotiating with the RIAA on your behalf. They finally realised what a bunch of nutcases these RIAA folk really are, they're sick of being pushed around by some corporate lobbyists, and are now actively pushing for a rewrite of that RIAA bill that would change the wording from "terrorism" to a mere "theft". And it looks like they might even have a chance of winning this one...
OK, and now for the serious answer: a cellphone tower can only support a limited number of simultaneously connected cellphones. It therefore needs to know exactly when a cellphone leaves its range, or disconnects from the network altogether, so it can free up its connection slot for use by another cellphone. Normally a phone communicates a disconnect to the tower whenever possible (for example if it's getting out of reach and connects to another tower, it then disconnects from the first and the connection gets transferred gracefully from the old tower to the new one, even in the middle of a conversation). However, if you just yank out the batteries, the phone gets utterly destroyed, you suddenly enter a cage of faraday or even an underground tunnel, ... the phone will have no time to notify the tower, so the tower needs to check up on supposedly connected phones from time to time to check that none of them are MIA. It's basically similar to an ICMP ping on the Internet. And that's what you hear over your speakers. Similar thing happens right before a call or SMS comes in, or when you dial out: there's two-way communication, and the RF interference the cellphone puts out is picked up by your audio equipment.
Re:T-Mobile vs Nokia (Score:2)
Re:Same Problem - Really Expensive Speakers (Score:2)
Re:Same Problem - Really Expensive Speakers (Score:2)
"Ladies and Gentlemen, welcome to tonight's production of Antigone. As a courtesy to the performers, crew and to your fellow audience members, we ask you to check that pagers, mobile telephones and other electro
Re:Happens with CDMA and GSM, all Frequencies... (Score:2)