Cell phone interference

[Stan Olson]

Back in November 2005, I switched from Verizon (CDMA network) to Cingular (GSM network) for my cell phone provider. I've been really pleased with the coverage area especially the data coverage. (the main reason for switching) The problem is the phone (Motorola v551) interferes with everything: computer speakers, car speakers, ham/scanner speakers, and even my camcorder video/audio. The camcorder one is the most frustrating because it ruins both the video and audio feeds. I tried hooking up an external antenna to the cell phone to hopefully directly all the signals outside of the car, but that didn't seem to help. It only seems to affect it when I'm talking on the phone, receiving/sending text messages, or using data via the phone-computer. If it's just idle, then I don't notice any interference. The problem is that I use continuous data when I'm watching storms, so getting offline/shutting the phone off really isn't the best solution. I must also mention this phone uses Bluetooth as well, but I don't think that's where the interference is coming from. I'm not sure if this phone just has faulty shielding, or if they're using different frequencies than my Verizon phone used. My coworker also switched to Cingular in January and his phone does the same thing. Anyone have any ideas to shield the phone from getting into other things? Thanks!

Stan

 

[Jeff Snyder]

Hmm. I have a Moto MPx220 on Cingular, and haven't noticed any real problems (well, at least with the situation you are addressing). I do get some audio speaker interference once in a while (some popping/buzzing sounds), but I assume that's just when my phone talks with the network (voicemail update? something along those lines I assume). I'm not sure what freq Cingular uses around here (850 or 1900mhz), but I know my speakers can pick it up if I'm close enough to them. Other than that, however, I haven't noticed any issues. Perhaps the RF on your phone is leaky.

 

[John Diel]

I've had some minor issues over speakers, but never when recording. Use of an external antenna "should" remove the issue as well. At least it does for me.

It's not a very strong signal, I generally carry my phone on my belt and can simply turn and wipe out the RFI. The RFI only occurs when I'm on a call, or the phone is checking it's staus against the network.

I tend to agree with Jeff here, If you're getting that kind of RFI, then you've probably got a faulty phone. As the new technologies come out and new RF Bands are being utilized, we are going to start seeing more of this as the new stuff starts walking on the older non-shielded stuff.

I record of lot of voice overs and such, and I get this type of interference all the time. Again, I'ver had it "ruin" or even show up on the final mix. I also use a wireless mic on my camera and haven't had any issues there either.

 

[Mikel Shively]

I have noticed that type of intererence with the older types of Nokia's but never with Motorola. I have a v720, and have never had it interfere with anything, regardless of whether I was using the external antenna or not. In fact, I have had it connected for long periods when I was using the phone as the modem and I have never had any problems. It may be just type of phone.

 

[Stan Olson]

Yeah, I'm not sure what's causing it but it ruined what little video I had from 3/12. I'm going to post over on howardforums and see if they have any thoughts. Thanks!

Stan

 

[James Siler]

CIngular broadcasts on the 850/1900 bands. Unfortanetly that is something that happens with GSM technology. There is no way around it, and i haven't found anything my self to make it stop. CDMA does not do it from what I hear. Hopefully (and from what has been said in trainging class) UMTS I don't think will have that problem. Unfortanetly, for this year and part of next year UMTS will be confined to the metro area's before it is deployed to the rual areas. It has made me mute much video in the past if the camcorder gets to close to pick it up. Guess that is where that whole FCC "this device must except any interferance it receives" comes into play.

 

[John Erwin]

I had the same problem when I was using a GSM phone. I found that relocating the phone to a different part on the dash (I use a mobile mount) and using an exterior antenna improved things immensely, although there was still the odd "bump-bump" noise heard softly on one of my car speakers once in a while.

As mentioned by others, CDMA phones don't seem to do this.

 

[Stephanie Koles]

Back in November 2005, I switched from Verizon (CDMA network) to Cingular (GSM network) for my cell phone provider. I've been really pleased with the coverage area especially the data coverage. (the main reason for switching) The problem is the phone (Motorola v551) interferes with everything: computer speakers, car speakers, ham/scanner speakers, and even my camcorder video/audio. The camcorder one is the most frustrating because it ruins both the video and audio feeds. I tried hooking up an external antenna to the cell phone to hopefully directly all the signals outside of the car, but that didn't seem to help. It only seems to affect it when I'm talking on the phone, receiving/sending text messages, or using data via the phone-computer. If it's just idle, then I don't notice any interference. The problem is that I use continuous data when I'm watching storms, so getting offline/shutting the phone off really isn't the best solution. I must also mention this phone uses Bluetooth as well, but I don't think that's where the interference is coming from. I'm not sure if this phone just has faulty shielding, or if they're using different frequencies than my Verizon phone used. My coworker also switched to Cingular in January and his phone does the same thing. Anyone have any ideas to shield the phone from getting into other things? Thanks!

Stan
[/b]

Yes, GSM by nature has a bursty RF signal that poses RFI issues when it is in close proximity to other sensitive electronic equipment. I am surprised the external antenna did not help somewhat. External antennas on cell phones are not exactly encouraged by cellular providers so that is not a real big market for this anymore. Importantly, the external antenna has to cover both 1.8Ghz and 800 MHz for the phone to work successfully. Placing the external antenna on the roof of the car would be the best alternative for this issue.