EVM我知道，可是95% EVM怎么理解？

all4you

小弟之前做wifi的，现在包括手机RF也要做了；故请大家多多指教：95% EVM怎么理解？？[em14]

DirverDev

95% EVM是指一个脉冲里不超过符号95%的误差矢量幅度；参数实际上忽略了所有误差矢量的最高的5%部分。[em12]

[此贴子已经被作者于2009-2-17 10:17:13编辑过]

[br]<p align=right><font color=red>+3 RD币</font></p>

fengmo44

我记得应该是和概率相关的，就是测试中95%的EVM要符合一个标准

ztemt

只有5%的测量结果可能不准确。

luojiayou

ETSI规范中,定义95%EVM为:量测200个脉冲的有效部分.在每个符号会有EVM的值,95%EVM就是指所有EVM值按大到小排列在第95%位置的EVM的值.[br]<p align=right><font color=red>+3 RD币</font></p>

all4you

感谢兄弟们的回答。。。之后继续加深理解……

pp_boby

以下是关于EGDE的，应该可以借鉴下！
指的是8PSK的的指标，是说在所有测试的EVM分布，EVM值从小到大排列，排列到第95％的那个sysbom的EVM的值要小于15％，
（The measured 95th-percentile value shall be < 15 %，The measured peak EVM values shall be < 30 %，
the measured RMS EVM over the useful part of any burst, excluding tail bits, shall not exceed：for MS:
under normal conditions  9,0 % under extreme conditions 10,0 %）
可以参考3GPP TS 05.05关于EVM的部分，讲的很清楚。

EVM 95%置信度测试:具体解释如下:(至于仪器是如何实现该项测量的,你可以问问RS,Agilent的人,射频工程师只需要关注指标是否OK就行了)

The maximum acceptable uncertainty of the Test System is specified below for each test, where appropriate. The Test
System shall enable the stimulus signals in the test case to be adjusted to within the specified range, and the equipment
under test to be measured with an uncertainty not exceeding the specified values. All ranges and uncertainties are
absolute values, and are valid for a confidence level of 95 %, unless otherwise stated.
A confidence level of 95 % is the measurement uncertainty tolerance interval for a specific measurement that contains
95 % of the performance of a population of test equipment.
For RF tests it should be noted that the uncertainties in clause F.1 apply to the Test System operating into a nominal 50
ohm load and do not include system effects due to mismatch between the DUT and the Test System.[br]<p align=right><font color=red>+3 RD币</font></p>

rocky2010

这样看来应该是5%的PER（丢包率）就是说发送1000个数据包接收时有5%的错误，做wifi一般控制在8%以内的！[em01][em01][em01][em01]