Buzzing on GSM audio

Dave Clark rivalarrival at
Sat Jul 26 03:30:20 CEST 2008

Jim Morris wrote:
> Dave Clark wrote:
>> Can you correlate the buzzing to your signal level?  IIRC, most phones 
>> will increase transmit power as needed to overcome noise.  If the noise 
>> is caused by RFI from the GSM radio, increased power would tend to 
>> increase the interference.
> I have a very low signal here one bar at most, I haven't tried it where there is good reception, as 
> I can't really use it as a phone yet. However with that clue I'll try it ASAP in an area where I get 
> better reception.
> FWIW my other Cell phones also get very low reception here, but don't have any noise.
> I hope if this is a H/W problem we can get it fixed even after the warranty expires as it definitely 
> makes the phone a brick otherwise.
I know GSM transmissions can present significant interference on audio 
equipment - if my phone (any GSM phone) is on my desk, I can hear 
periodic static in my computer speakers as the phone "checks in" with 
the cell tower - it sounds like three quick, buzzes in about 1 second. 
This happens a couple times an hour.

When it receives a call, I get a steady buzz starting 1 to 3 seconds 
before the phone rings, and continuing until I hang up.

I would imagine that ALL cell phone hardware would have to deal with 
this audio interference, and since I don't hear it in many other phones, 
I'm pretty sure it can be filtered out with some sort of audio processing.

Incidentally, the speaker-phone feed back could probably be resolved 
with the same filter.

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