本文分析了用相关方法进行在线测辨所引起的误差。讨论了由于外加噪声的带宽有限而引起的测量偏差以及由于测量时间有限而引起的随机误差。文中对正态外加噪声和M序列外加噪声进行了具体计算(这两种噪声实现起来都很简单)。对于一阶系统,在相同的输出端信/噪比的情况下,M序列的随机误差比正态噪声大一倍左右。 This paper analyzes the errors caused by the online methods of the related methods. The measurement deviations due to the limited bandwidth of additive noise and the random errors due to the limited measurement time are discussed. In this paper, the normal additive noise and M-sequence extraneous noise are calculated (both of them are very simple to implement). For the first-order system, the random error of the M-sequence is about one time larger than the normal noise at the same output signal / noise ratio.