AGC (Automatic Gain Control)

Supported ICs

• Speech Recognition Mode

  • RTL8721Dx

  • RTL8726E

  • RTL8713E

  • RTL8730E

• Voice Communication Mode

  • RTL8726E

  • RTL8713E

  • RTL8730E

Overview

Automatic gain control is one of the AFE’s functions, to adjust the amplitude of the output audio.

Algorithm Description

The AGC in AIVoice consists of two submodules: Fixed gain and Adaptive AGC:

• Fixed Gain

  • Speech recognition: When the output signal amplitude obviously affects the KWS or ASR effect, the AGC module can be enabled to apply the appropriate gain.

  • Voice communication: Except for special requirements, thefixed gain needs to be enabled.

• Adaptive AGC

  • Speech recognition: Not supported.

  • Voice communication: Except for special requirements, theadaptive AGC needs to be enabled.

Configurations

The complete AFE configuration file is located at ${aivoice_lib_dir}/include/aivoice_afe_config.h. The AGC-related configurations include:

afe_mode_e afe_mode;                    // AFE mode, for ASR or voice communication.
bool enable_agc;                        // AGC(Automation Gain Control) module switch

// AGC module parameter
int agc_fixed_gain;                     // AGC fixed gain(dB) applied on AFE output, the value should be in [0, 18].
bool enable_adaptive_agc;               // adaptive AGC switch. Only supports voice communication mode.

When adjusting the AGC_fixed_gain parameter, ensure that the processed signal is not clipped under maximum speech volume conditions.