Buzzing on GSM audio (settings also work well with GTA01)

Eric Olson eric at ericanddebbie.com
Sat Jul 26 19:12:21 CEST 2008


I spoke a little too soon.  A real test talking to someone else still 
had echo.  So, it's better, but could still use improvement.

Eric

Eric Olson wrote:
> Hi,
> I'm just confirming that this helps audio on GTA01 as well.  Testing 
> with another phone, I was able to get rid of echo almost entirely 
> (between our two phones) by reducing Mono Playback Volume to 72. 
> Hopefully, this will be loud enough to hear well in noisy places -- I'll 
> have to try that out.
> Here are the relevant numbers I settled on for now:
> (Tmobile US, other side was a cell phone, indoors -- not a noisy area)
> 
> Mono Playback Volume 72
> Speaker Playback Volume 118
> Mic2 Capture Volume 3
> Mono Sidetone Playback Volume 7
> Bypass Playback Volume 7
> 
> On another note, the headset seemed to work well just now unless the 
> headset mic was brought near the other phone or was touching the usb 
> cable near the neo.  I didn't test it very long -- I'm sure there are 
> other things that can cause interference.  At least I could hear some of 
> the buzz on the neo side, so I can at least test it in everyday use and 
> tell if there's interference (instead of entirely relying on the other 
> person to tell me there's a problem like I did with echo).
> 
> Eric
> 
> 
> Timo Jyrinki wrote:
>> 2008/7/26 Andrew Bruno <aeb at qnot.org>:
>>> FWIW, I've found tweaking these specific settings in
>>> /usr/share/openmoko/scenarios/gsmhandset.state effect the intensity of the
>>> buzzing sound. Specifically:
>>>
>>>  * 'Mono Playback Volume'   (85)
>>>  * 'Mono Sidetone Playback Volume'  (7)
>>>  * 'Mic2 Capture Volume'     (3)
>> (buzz)
>> ...
>>>  * 'Speaker Playback Volume'  (112)
>>>  * 'Bypass Playback Volume'    (7)
>> (echo)
>>
>> Thanks! With these tweaks to my current settings, I've successfully
>> for the first time received a confirmation that the receiver of my
>> call didn't hear an echo of her own voice.
>>
>> However, I did tweak "Mono Sidetone Playback Volume" from 7 to 4,
>> since in my own testings with two phones I heard quite a lot of buzz
>> still. That lessened it, and the receiver seemed to hear my well
>> enough anyway.
>>
>> My paranoid / not-knowing-what-I-do procedure is to:
>> 1. change /usr/share/openmoko/scenarios/gsmhandset.state
>> 2. alsactl -f /usr/share/openmoko/scenarios/gsmhandset.state restore
>> 3. alsactl -f /etc/asound.state store
>> 4. reboot
>>
>> I now added a link to your post at
>> http://wiki.openmoko.org/wiki/Freerunner_Hardware_Issues#Poor_Audio_Quality
>> since this is the first time I really achieved some good results.
>>
>> -Timo
>>
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>>
> 
> 
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