谢谢楼上各位大侠的赐教,多谢!和7楼朋友讨论一点,您关于"synchronous"的观点我完全同意。但是对于Peak hold的观点,我不敢苟同,我感觉Peak hold应是在时域中进行的。文献摘抄如下:"Peak hold is not a true averaging method. During sampling time, the peak value registered in each analysis cell is captured and displayed. This method is very useful in viewing transients or for stress analysis calculations" Dennis H. Shreve