包络分析大多在原始振动加速度信号基础上进行， 受噪声干扰等因素的影响较大 通过对原始振动信号自相关函数作包络分析， 可以有效地抑制噪声， 突出反映故障调制特征-s． Most of the envelope analyses are based on original vibration accelera-

tion signal，which is seriously influenced by noise interference． The noise is effectively suppressed by envelop analysis

of auto correlation function of original vibration signal，and the modulation characteristics of fault are highlighted．