GSM Radio Interference: How do you Fight it?

[Foxbat]

I don't know why I seem to notice GSM interference around me and my iPhone, but it is starting to really annoy me when my desk phone at work is constantly picking my phone's "zgh-zgh-zgh, zgh-zgh-zgh, zgh-zgh-zgh" as it checks in with AT&T. I hear it on my computer's speakers at work, my cheapie speakers on my son's PC; pretty much anything with speakers and not much shielding.

I first noticed this interference with my first digital cell phone, a Motorola G180. I also experienced it with my RAZR and RAZR 3xx flip phones. But nothing as bad as with the Apple iPhone 4.

I found that if I put my iPhone in an anti-static bag (like a disk drive would come in,) it seems to cut way down on the interference. My iPhone still seems to be able to receive phone calls, and peering through the smoked grey plastic film, it doesn't seem to affect the signal strength. However, if I get a phone call while the phone is in the bag (egads, I've returned to using a bag phone!) I have to open the bag and pull out the phone to answer it.

Have other people noticed this phenomenon with their cellular phones? Does GSM vs CDMA make a difference? Have you figured out a way to limit the interference without crippling the phone?

 

[aegrotatio]

In most areas, AT&T uses 850 MHz GSM and they cause very loud zgh-zgh-zgh noises. In areas where they use 1900 MHz it's very quiet. I consider it more of an advantage because those cell phone providers who have 850 MHz coverage have superior coverage.

A while ago there had been some white papers published on how to reduce the dit-dit-dit sounds, but only on the internal speaker of the cell phone, not of speakers and speakerphones located nearby.

Personally I want my ringtone to be the GSM dit-dit-dit-zgh-zgh-zhg sound. I think it's endearing.

 

[Steve Mehs]

I fought it by getting moving to CDMA Dumping the iPhone gave me a much better phone running a much better OS, better service, lower bill and no annoying interference. Since I have my phone charger on my desk right next to my rear right PC speaker, I'd get interference all the time.

 

[Ramy]

What does CDMA use?

 

[Big Dawg 23]

I believe CDMA is 900/1700 or something close. The radio interference can be annoying on GSM.

 

[Foxbat]

They re-skinned the office building at work with these insulated metal panels and replaced the windows with High-E windows, all of which eliminated any cellular radio from inside the building. We had to install Wi-Ex ZBoost cellular repeaters in the offices with yagis up on the roof pointed to the nearest cell towers. We get better cell signals than before, but that's when the radio on my iPhone started interfering with my desk phone. According to the Wi-Ex web site, the ZBoost units we have cover both 850 MHz & 1900 MHz, so maybe the issue is the cell tower they aimed at uses the 850 MHz signal only.

Makes me wonder if there is a web site that tracks cellular towers, their locations, and their frequencies. Edit: Thanks, Google! http://www.cellreception.com/towers/towers.php

 

[truckracer]

EDGE on at&t makes the noise where as 3G does not here. that is not an iphone specific issue. its a lack of shielding issue with your office phone system. future attention by business system manufacturers will have to be given to this issue. the office systems will have to be shielded and filtered properly not to allow rf interference from mobile devices.

 

[Foxbat]

That sounds likely. I don't think we've ever seen 3G where I work.

 

[digiblur]

Not sure if you would see it if you were in a 850 3g area for at&t. The same bands are used by CDMA but the interference you notice does not happen even if you are in an 850 CDMA location. Evident when I am in one location of work and roaming on 850 cdma with only one bar of coverage. So the phone is yelling full out to reach the tower.