calypso hardware echo suppression?

[Bruce Bertrand]

On Wed, 2008-08-27 at 05:39 +0800, Joerg Reisenweber wrote:
> Am Di  26. August 2008 schrieb Al Johnson:
> > According to http://wiki.openmoko.org/wiki/GTA01_gsm_modem#AT.40AUL the 
> audio 
> > table has parameters for echo suppression and AGC. Does this mean that the 
> > GSM chipset has echo suppression hardware?
> 
> I guess that's actually the case.
> I'm investigating (on low priority though) how to exploit these functions of 
> calypso chipset.
> Any additional info / participation on task appreciated :-)
> 
> cheers
> jOERG

Just to be clear, echo suppression is not the same as echo
cancellation.  

In the latter, the output of the speaker is inverted and adaptively
added to the mic input so as to cancel out acoustic coupling.

Echo suppression simply tries to detect when you are silent (ie.
listening to the other party), and mutes the mic input.  When you speak
it unmutes the input.

~B