[Community] Is it possible to deactivate the silence suppression on a GTA02 and/or GTA04?
psonek2 at seznam.cz
Tue Dec 11 16:23:19 CET 2012
On Tuesday, December 11, 2012 12:04:59 PM Wurzer Juergen wrote:
> Is there a way to deactivate the silence suppression during a phone call on
> a GTA02 and/or on a GTA04? Maybe like setting the level of the voice
> activity detection (VAD) to a minimum, so that it always stays "active"
> and continuously transmit the voice.
> I need this because we have a research project where we embed
> steganographic informations during a call into the voice stream. The
> current problem is that if the audio signal is very quiet (e.g. the person
> doesn't speak) nothing is transmitted because of the silence suppression -
> this leads to the steganographic informations being discarded.
On GTA04 it's possible to do software voice routing - i think in this case the
sounds will be under your control. If you want to test it, try make a call and
then select "Speaker" from the context menu. The sound will be then routed by
program /opt/qtmoko/bin/gsm-voice-routing - source code is here . By
default it uses speex echo cancellation, but these lines can be commented out
or you can even replace the program with bash script that calls arecord and
aplay - see here 
> Maybe there are AT commands?
> I have tried to set some AT commands like the ones shown at
> http://wiki.openmoko.org/wiki/Manually_using_GSM on GTA02.
You can stop QtMoko with /etc/init.d/qtmoko-gta04 stop and open and use the
serial port e.g. with minicom.
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