Let us try to understand what waterfall frequency spacing is. Waterfall frequency spacing is the gap between spectral lines in an FFT plot. For example, if you had an analysis frequency of 0Hz to 100Hz and 100 spectral lines, then Frequency Spacing is 1Hz. So why is there a ‘Requested Frequency Spacing’ and an ‘Actual Frequency …
Tag Archive: waterfall
When analysing a waterfall or performing order analysis it is important to consider the frequency resolution or the frequency spacing. There is often a desire to increase the resolution to finer and finer detail. But that is a process of diminishing returns, and actually fraught with danger. And that danger is waterfall smearing.
A user has three signals captured using a triaxial accelerometer and asked “What is the simplest way to get the XYZ resultant from run-up file?” He had tried forming a resultant of the raw time histories, but didn’t fully understand the resultant time history. Of course, the correct way of processing the data is to …
A step-by-step introduction to creating order and waterfall plots from a time history and a tacho signal.
July 4, 2012
Use the following sequence to get the Articulation Index (AI) vs rotational speed: Perform waterfall analysis on your noise signal (+ tacho). This gives you a standard waterfall display On the waterfall result perform the analysis Analysis->Noise, Vibration and Harshness->Spectrum Input->Sound Quality Auto Extract Number of Cylinders = x (set to appropriate value) Write metrics …
James Wren explains how to view 3-D visualizations using linear, logarithmic & dB scales.
December 16, 2011
This is complete version of the video illustrating my recent article How To Measure Noise & Vibration In Rotating Machines. This video was previously published on the blog in 3 parts.
The video will be best enjoyed by selecting the 720p option and selecting full screen mode.
October 4, 2011