ABSTRACT
Filtering is examined in the same sense as that used in system vibration analysis; that is to say that the frequency characteristics of the input signal are operated on by the same method whether electrical, mechanical or computational. Digital methods arise in two major areas: the first is in the analysis of the various waveforms, and the second is in the use of computers to control instruments, machines, etc. Random sampling has also been used where fewer samples need to be taken but the problem then arises of unscrambling the data afterwards. The problem of defining peaks and assessing peak properties often arises in metrology, especially in contact theory. The technique of using discrete measurements has application in fields where it is expensive or time consuming to obtain large amounts of data. Filtering methods are the natural way to isolate specific bands of information of the surface.
