TD—SCDMA的EVM测试及分析

从误差矢量幅度(EVM)的定义及互相关系数的关系出发，研究了TD—SCDMA的EVM的测试方法及具体实现。结合TD—SCDMA的硬件结构分析了影响EVM指标的主要因素，对其作了推导说明，并给出了相应的仿真结果。为能达到指标要求，对影响EVM指标的几个因素给出了具体的规定，为提高终端EVM性能提供了理论基础，且有一定的实际指导意义。

EVM testing and analysing in TD-SCDMA

In this article, the definition and test schemes of EVM are presented. Mostly, the article describes the measures taken for EVM in TD-SCDMA and analyzes factors affecting the result of EVM based on the structure of the TD-SCDMA Ms. The corresponding EVM formulas and computer aided numeric results are also given. It points out why and to what degree these factors affect the result of EVM. Factors the article refered to must be restricted in order to achieve good performance. In real project, maximum phase error should be no more than 3 degrees in angle.and phase noise for TD-SCDMA should be less than 1.1 degree in angle and so on. The article analyzes the influence on EVM of each kind of signal distortion. It supplies academic basis for improving EVM performance of Ms. The article has some value in guiding real work design.