对国家标准《GB/T13639-2008》的一点质疑

Some Query to the State Standard 《GB/T13639-2008》

对国家标准GB/T 13639-2008《工业过程测量和控制系统用模拟输入数字式指示仪》中规定的共模干扰抑制比CMRR和串模干扰抑制比SMRR的指标值进行讨论。认为不同种类的模拟量输入装置,应根据相应的信号电量程和测量精度等级,规定它们各自的CMRR和SMRR。并建议采用(ΔU/F.S)×100%≤a%作为模拟量输入装置其抑制共模干扰和串模干扰的指标。

The index for common mode rejection ratio and series mode rejection ratio coded in the state standard 《 Digital indicators with analogue input for use in industrial-process measurement and control systems》 （GB/T 13639 -2008 ） is discussed. Specificity of CMRR and SMRR for different AI modules should be coded according to full scale and accuracy class of module. The following formula is suggested as the index of common mode rejection and series mode rejection for AI modules （AU/F. S） ×100%≤a%.