基于虚拟仪器的矢网分析仪时域反射技术研究

The study of time-domain reflection technique of vector network analyzer based on virtual instrument

理想信号传输的波形是平滑稳健的,但实际电子元件测量过程中,经常会遇到接口阻抗不匹配的情况发生,为了找到阻抗不匹配的具体位置以及分析该处的信号特性,采用时域反射技术解决。当原始测量数据经过无时域功能的矢量网络分析仪后,即可获得待测器件真实的频域参数,再通过滤波、时域转换、时域选通、频域转换后可得到反射频域参数,经过原始和反射参数对比后,波形不一致处即为阻抗不匹配点,进而可以分析该处的信号特性。根据时域选通的数学表达式,采用时频变换及时域选通的模型并编写相应的程序来完成虚拟仪器的设计。结合LabVIEW和MATLAB编写程序并实现测量功能,最后给出实际测量的信号显示结果,对结果进行分析并解释出现失真的原因。

The wave shape of the ideal signal when transferring is very smoothly, but in fact, when detect the electronic elements, we always come across some conditions like impedance mismatching, in order to find the position of mismatching and analyze the character of the signal, Adopting the method of time-frequency transforming, The original parameters pass through the vector network analyzer which without time-domain function, the real frequency parameters of DUT will be obtained, and then, by the methods of filtering, time-domain transform, time-domain selecting, frequency transform, The reflex of the frequency parameters can be obtained, by comparing the original and reflex parameters, the position where the two parameters are different has been mismatched. By studying the mathematical expression of time-domain function, use time-frequency transforming and time-domain gate to complete this design. Combining LabVIEW with MATLAB to design the program and carry out the time-domain measurements. The signal displayed on the screen will be given at last and the actual measurement and the result of transforming will be given to analyze.