一种新的音频分析系统的实现方法

失真度是无线电信号测试的一个重要参数.提出一种以数字处理芯片DSP和MCU为基本结构,两路DDS芯片及幅值调节电路完成双音频信号发生,快速傅里叶变换来实现对正弦信号失真度的测量方法.DSP芯片为FFT算法提供的快速专用指令,使得程序在快速性和测量精确性方面有很大提高.上位机通过双口RAM完成对音频分析与信号发生模块的实时控制.实测结果表明,系统SINAD值测量准确度优于±0.3 dB、失真因素优于0.2%,可以有效的完成电子系统的综合测试并替代国外同类设备,满足实际应用需求.

New solution to signal generator and distortion analyzer

The effect of nonlinear distortion has been recognized. An audio frequency analyzer with frequency spectrum measurement range of 20～10 kHz is introduced. This equipment consists of a pair of special purpose instruments: a signal generator and a distortion detector. Based on two highly linear signal generators and feedback control amplification circuit, a method using a 16-bit AD converter and DSP to work out the distortion of audio signal is given. An improved FFT algorithm is used for audio signal spectrum analysis, and large improvement in speed and precision is achieved. The parameters that can be measured are harmonic distortion, SINAD, frequency and RMS. The results show that the waveform generator and distortion analyzer have excellent performance, and the errors of SINAD and THD measurement are less than ±0.3 dB and 0.2% respectively.