A booklet covering High Frequency Enveloping & Demodulation Techniques (59 page booklet)
• This paper will first define what is meant by the term "high frequency enveloped and demodulated spectra".
• These spectral techniques are used by a number of different vendors and, basically, tend to function similarly.
• However, there are slight differences or variations in the methods and techniques which each vendor employs; and each vendor has their own particular "name" they apply to such data.
• The purpose of this paper will not be to compare which of the techniques are better than others, but instead will concentrate basically on how they function, what instrumentation is required, what frequency setups should be employed (band-pass filters, low-pass filters, high-pass filters, etc.), and what mounting techniques as well as special treatments of mounting surfaces must be employed to ensure successful measurement accuracy and repeatability using these technologies.
• This paper will also provide example spectra captured by data collectors from several different vendors. The highlight of this paper is a series of tables (Tables II thru IV) that will enable the analyst to specify the proper band-pass, high-pass or low-pass filter needed, depending on his particular analyzer in order to effectively detect bearing, gear, and other faults in the HFE spectra and waveforms.
• Finally, information will be provided on how high frequency demodulated spectra can be used to detect problems with bearings, gears, lubrication, rotor rub and certain electrical anomalies.