Automatic Gain Control¶
Abstract |
Automatic Gain Control |
Authors |
Walter Fan |
Status |
WIP |
Updated |
2021-12-29 |
概述¶
自动增益控制（AGC）是指当直放站工作于最大增益且输出为最大功率时，增加输入信号电平，提高直放站对输出信号电平控制的能力。
自动增益控制主要用于调整音量幅值。
正常人交谈的音量在40~60dB之间，低于25dB的声音听起来很吃力，超过100dB的声音会让人不适。AGC的作用就是将音量调整到人接受的范围。
AGC的调整分为模拟部分(AAGC)和数字部分(DAGC)，模拟部分是麦克风的采集增益，数字部分是音频数据的数字电平调整。
Calculate the short-term mean and variance, describe the instantaneous change of the voice envelope, which can accurately reflect the voice envelope,
Calculate the long-term mean and variance, describe the overall slow change trend of the signal, outline the “center of gravity” of the signal, and it is more smooth to use the threshold as the detection condition, such as Figure 2 left blue curve ;
Calculate the standard score and describe the deviation of the short-term average from the “center of gravity”. The part above the center can be considered as having a great possibility of voice activity;