相位差测量系统的硬件电路

Hardware circuit desing of phase difference measurement system

为精确测量两个同频率信号的相位差,设计一种基于DSP的相位差测量系统。该系统采用DSP2812作为测量的主控芯片,其内部集成有捕获单元和A/D模块;运用信道交换技术和降频技术,消除通道带来的附加相移,并将高频信号转化为低频信号以便于测量。测试结果表明,两路输入信号相同时,输入信号频率过大或是过小,测量频率和相位的精度均会明显降低,幅值精度变化不大;两路输入信号峰值、频率相同,相位可变时,信号频率增加或信号幅值过小,系统的测量精度均会有所下降。该相位差测量系统能够实现对两路同频信号的幅值、频率和相位差的精确测量,且可以进一步扩展以实现对多路信号相位差的测量。

For accurate measurement of the phase difference of the two same-frequency signals, a kind of phase difference measurement system based on DSP is designed. As the main control chip in the system, DSP2812 integrates capture unit and A/D module; Channel exchange technology and frequency reduction technology are used to eliminate additional phase shift by channel, and convert high frequency signals to low frequency signal before being measured. The test results show that the two input signals are the same, if the input signal frequency is too large or too small, the accuracy of measuring frequency and phase will be significantly reduced, little change in amplitude accuracy; two peak input signal, the same frequency, the phase can be changed, the increase in signal frequency or signal amplitude is too small, the system ac- curacy will decline. Experimental results show that the phase difference measurement system can well measure amplitude frequency and phase difference of two input signals with the same frequency. The system can also be further extended to realize to phase difference measurement of multi-channel signals.