对生活中常见的啸叫现象,设计了一个具备啸叫检测与抑制功能的实时音频功率放大系统.根据啸叫产生前期的频域特征,采用FFT对音频信号进行频域转换,并采用峰值平均功率比方法检测啸叫频点;采用基于可编程滤波器的硬件滤波电路完成啸叫的抑制;并设计了高效率数字音频功放电路、拾音电路及输入滤波电路.实验表明该设计频点检测准确、啸叫抑制效果明显、音频无明显失真.相比复杂的全数字算法搭配高性能处理器的抑制方式,具有成本低、设计难度低、硬件抑制电路响应更快等优点,在多媒体教室、学术报告厅及会议室等实时扩音场合有较高的实用价值.%A real-time audio power amplifier with howling detection and suppression is designed to solve howling phenomenon in our daily life.According to the frequency domain characteristics before howling occurs,the frequency domain conversion of audio signals is carried out by FFT,and peak-to-average power ratio is used to detect the howling frequency.A hardware filter circuit based on programmable filter,MAX262,is designed to suppress the howling.The high efficiency digital audio power amplifier,pickup circuit and input filter circuit are designed.Experiments show that this design is accurate in howling frequency detection,it is obvious in howling suppression effect and has not significant audio distortion.Compared with the complex suppression way that all-digital with high performance processor,it has the advantages of low cost,low design difficulty and fast hardware suppression circuit response.In the real-time sound reinforcement occasions such as multimedia classrooms,academic lecture halls and conference rooms,it has a high practical value.
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