Buzzing on GSM audio

christopher bradski chris.bradski at
Sat Jul 26 07:09:46 CEST 2008

On Fri, Jul 25, 2008 at 9:47 PM, Sparrow <sparrow at> wrote:

> Evening Folks,
>        I just wanted to enquire if anyone has started to gather info on
> which
> bands are being using during calls that have the buzzing occurring?  I
> used to work with a wireless telecom provider here in Canada in the R&D
> lab, and when issues like this came up with new handsets (which happened
> alot) we always started by creating an issue profile containing
> information such as:
> 1) Wireless band being used.
> 2) Geographic location.
> 3) Cell Side equipment (hard to determine without details from the
> providers)
> 4) Signal Strength (receive and transmit)
> 5) User call quality (0 to 5)
>        Perhaps we could put together a little application have would
> capture
> this data and dump it to a file.  It may help the openmoko folks target
> their investigation.
> On Sat, 2008-07-26 at 12:02 +0800, Joerg Reisenweber wrote:
> > this we have to spot the exact way RF is entering back to the device.
> > That's
> Best regards,
> Steven O'Reilly
> _______________________________________________
> support mailing list
> support at
Just curious if there is a gsm "saw filter" somewhere in the audio path (or
another filter by the amp)? Also, I haven't popped open my freerunner yet
but could another fix be that a small capacitor could be strategically
placed to filter out the noise (like the sd card issue (worked in my car
audio....))? Sorry for so many questions/possibilities... Is the Vcc path to
the gsm transmitter to close to an audio path or could it just be something
is tied down to an incorrect ground location? I'm sure the Openmoko team is
already on top of this though.

On a second note: I'm really happy with the freerunner and having a phone
that I can tweak to my liking. Also a good hint would be to considr an image
for the background when using ASU. It looks a thousand times better when the
app icons have something other then black behind them. IMHO :) (by the way
what does this really stand for? I only have an idea...)

Keep up the good work. Much appreciated.
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