LabVIEW数字调制误差测量模块的改进

Improvement on MT measure PSK quadrature impairments Ⅵ of LabVIEW modulation toolkits

本文首先介绍了数字调制误差的概念,给出了LabVIEW调制工具包中PSK数字调制误差测量模块(MTMeasure PSK Quadrature Impairments)工作原理,然后以EVM测量为例分析了测量误差,根据数字调制解调过程中所使用的数字脉冲成形滤波器与匹配滤波器实现方法,得到测量误差是由数字滤波器引入的截断误差导致的结论。根据误差分析结果,本文建立了新的数字调制误差测量模块,新模块的参考信号生成过程使用与调制解调过程相同的滤波器环节,引入相同的截断误差,从而抵消被测信号在数字调制解调过程存在的滤波器截断误差。最后通过LabVIEW仿真测量实验,证明了新模块提高了测量精度。

In this paper, the concept of Digital Modulation Error is introduced, and the principle of MT Measure PSK Quadrature VI is given. Then take the EVM Measurement as an example, the measurement error is analyzed. According to the realizing method of digital pulse shape filters and matched filters in digital modulations, it concludes that the error is induced by the filter truncation error. Based on the conclusion, a new measurement VI is created, which uses the same filters as they use in digital modulations in reference signal generation process to introduce the same error to counteract the errors in digital modulations. Finally, it is proved that the new measurement VI is more accurate than the MT Measure PSK Quadrature VI by the simulation.