Tag Archive: waterfall

Aug 28

What is waterfall frequency spacing? And how does the DATS parameter ‘Requested Frequency Spacing’ work?

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 …

Continue reading »

Aug 20

What is “waterfall smearing”?

Waterfall created using a suitable frequency resolution

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.

Continue reading »

Jul 18

How Do I Get An XYZ Resultant Waterfall

Example worksheet calculating a resultant waterfall from x, y & z measurements from a triaxial accelerometer

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 …

Continue reading »

Video

[Video] Creating order & waterfall plots

A step-by-step introduction to creating order and waterfall plots from a time history and a tacho signal.

May 16

How Do I Get Articulation Index (AI) vs. Speed?

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 …

Continue reading »

Video

[Video] Displaying 3-D views using a linear, log & dB scale

James Wren explains how to view 3-D visualizations using linear, logarithmic & dB scales.

Video

[Video] How To Analyze Noise & Vibration From Rotating Machines

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.