基于FPGA和MAX262的啸叫检测与抑制系统

The oscillation detection and feedback suppression system based on FPGA and MAX262

针对扩声系统时常因啸叫严重影响现场扩音质量的问题,文中根据扩声系统啸叫产生的两个条件和两个特征,即回声满足的幅度和相位条件、啸叫满足的频率稳定和幅度稳定的波形特征,设计了一种基于FPGA和MAX262的啸叫检测与抑制系统。该系统由FPGA和AD637构成的检测电路对音频信号的频率和幅度分别进行检测,并根据检测的幅度和频率两个技术参数来判定是否产生啸叫,通过配置两片程控滤波器MAX262基于窄带陷波和全通移相原理来达到抑制啸叫的目的。该系统放置于麦克风与功率放大器之间,可用于众多现场扩音系统进行实时检测和抑制啸叫,具有重要的实用意义。

Aiming at the problem that the quality of site sound amplification system was seriously affected by the oscillation, the paper designed a kind of oscillation detection and feedback suppression system based on FPGA and MAX262 according to the conditions of amplitude and phase of the echo, and the oscillation waveform characteristics of frequency stability and amplitude stability which also are the conditions and characteristics of sound amplification system oscillation. The system detects the frequency and amplitude of the sound signal by the detection circuit consisted of FPGA and AD637 and judges the oscillation according to the frequency and amplitude which have been tested. The system aims at suppressing the oscillation by FPGA disposing two pieces of programmable filter MAX262 which is based on narrow band notch and all-pass phase shift principle. The system, which is placed between the microphone and power amplifier, can real-time detect and suppress the oscillation of many kinds of site sound amplification systems. The system has important practical value.