We are trying voice-calling over HE910-EUR-Modules.
The HE910-EUR is connected to an WM8994-Codec.
We setup the the HE910-Module with
AT#DVI=1,2,0 AT#DVIEXT=1,1,3,1,0 AT#DIALMODE=2 AT#SHSNR=1 AT#SHSEC=1 ATDT;
When we connected to a fixed phone line we have a good voice connection.
Now we try to setup a voice connection to a cell phone. We have loud feedbacks (backcoupling) with a delaytime of nearly 1 sec.
At the HE910-Speaker we have no Echo. But the person who calls the HE910 can hear a loud echo if he use a cellphone.
Do you have any ideas what we could do to aviod this echo?
In order to full operate the echo canceller remember to add the follow on init sequence:
Also notice when using an iPhone to make the call that iPhone set as a preferred audio CODEC e wideband codec AMR; in this case it’s a normal operator’s policy to allow it and open the traffic channel
to the other call party with the same CODEC in order to avoid a format conversion and save its resources. This is all fine, but AMR require a 16 KHz sampling rate and HE910 echo canceller is not yet optimized
on 16KHz so could work not at its best.The workaround to avoid this is to use AT#CODEC=95 in order to not allow AMR-WB codec to be used and let the operator the codec exchanging job.
The AT Commands in this post fixed the same type of echo we were having with the HE910. Also great to know that the HE910 echo canceller works better at 8kHz compared to 16kHz. Thanks!!
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