Question about AT+QMIC parameters on EC25 for GSM calls

IoT Modules LTE Standard Module
1

Hi,
We are conducting audio tests over GSM networks using the Quectel EC25 modem and configuring it via AT commands.

We have some questions about the AT+QMIC command, which allows configuring two parameters that affect microphone amplification during audio transmission: txgain and txdgain.

According to the datasheet:

  • txgain: Numeric type. Indicates uplink codec gain and the range is 0–65535.
  • txdgain: Numeric type. Indicates uplink digital gain and the range is 0–65535.

In our tests, both parameters clearly affect the audio volume and quality, but we are not sure exactly what each one modifies or how they differ.

Could you please clarify:

  • What part of the audio signal is affected by txgain vs txdgain?
  • Are there best practices for adjusting these values when using GSM voice calls?

Thanks in advance!

2

Hi,@udossantos
For your reference. I hope it will be helpful to you.
Below is a picture shows what we could control with the QMIC &CLVL & QRXGAIN , and the conversion relationship with dB

image
image989×303 34.9 KB

And when setting the AT+QAUDMOD=3 and CLVL=5, the gain of QMIC and QRXFAIN, it would be 0db by default, you do not need to setting them again.