The digital tacho channel in a P8000 system offers better time resolution by dividing the main sample period by 16. However it is sometimes difficult to know what level the threshold should be set to so a facility to help you find the optimum level has now been added to the acquisition software. (more…)
It is sometimes necessary to perform high pass filtering to eliminate low frequency signals. These may arise for instance from whole body vibrations when perhaps our interest is in higher frequency components from a substructure such as an engine or gearbox mounting. The vibration levels are speed sensitive and the usual scheme is to record a once per revolution ‘tacho’ signal with the vibration data. The tacho signal, which ideally is a nice regular pulse train, is processed to find rotational speed and hence to select which part of the vibration signal is to be frequency analyzed. The most common form of analysis is a waterfall type such as shown below.
