呵呵,相位差的图形取自下面的这篇文章:
Yang Xueshan,Gao Feng and Hou Xingmin
Low-frequency characteristics extension for vibration sensors.
Earthquake Engineering and Engineering Vibration, Vol.3, No.1 June 2004, page 139-146
Fig 5. Typical frequency response of 99-1 vibraiton pickup