The instrument of distortion measuring is studied by using the PC and PCI data acquisition card to the automatic test Equipment of AMU. The principle of the device is the conversion of the FFT of signal.

• 针对飞机AMU自动测试系统中对音频信号失真度测量的要求,运用PC机和数据采集卡,采用加窗FFT、把整个主瓣的宽度作为基波值来计算基波分量有效值的算法实现了在计算机中对音频信号失真度的直接测量。