## “The History and Future of Fourier Analysis” Workshop at SAE 2015, Grand Rapids

Are you attending the SAE 2015 Noise and Vibration Conference and Exhibition in Grand Rapids, Michigan, USA from 22nd to 25th June 2015? Why not go and see Dr Colin Mercer, one of our principal authors, co-present the technical session –…

## Wide Band Integrators – What Are They?

For some time now it has been conventional ‘wisdom’ that using time based digital integration may cause amplitude errors in the result and that these get worse as the frequency increases. As a result of this, integration using Omega arithmetic has been prevalent by using Fourier Transforms of the signal. This, of course, remains a valid approach and is particularly useful if the data is already in the frequency domain, which was its prime purpose.

## Noise & Vibration Analysis: Back To Basics

Sometimes it doesn’t hurt to revisit some of the basic building blocks that form the foundation of what we do. And so we have gathered together a few of our most popular past articles that deal with the fundamental aspects…

## Negative Frequencies – What Are They?

Normally when we are analysing a signal it is a purely real signal, that is it has no imaginary part. A classic example is of course a sine wave. When we analyse a signal with a Fourier transform, typically using…

## What is Synchronous (Angular) Sampling?

The term synchronous data is usually applied to vibration or acoustic data that is captured from an item of rotating equipment at regularly spaced angle intervals as distinct from regularly spaced time intervals. The rotating part could be an engine,…

## 10 Educational Mechanical Engineering Videos

We’ve had a good look around YouTube and dug up a great collection of educational mechanical engineering videos. There’s a wide range of information here from simple maths tutorial to explanations of the inner workings of the internal combustion engine.…

## Amplitude And Energy Correction – A Brief Summary

Amplitude and energy correction has been and is a continuing point of confusion for many people calculating spectra from time domain signals using Fourier transform methods. The first thing to say, the information contained in data presented as amplitude and…

## Data Windows : What, why and when?

Before we discuss the use of data windows, we should first remind ourselves of three basic properties of the FFT (Fast Fourier Transform) process. First, energy information in signal must be preserved during transformation. That is, the energy measured on…

## Interpolation Versus Resampling To Increase The Sample Rate

These are two different techniques aimed at different objectives. First consider a simple sinewave that has been sampled close to the Nyquist frequency (sample rate/2). Visually this looks very pointy. We will examine it using a filter based interpolation and a…

## Vibration Monitoring Phase Measurement And The Tacho Signal

Any vibration signal may be analyzed into amplitude and phase as a function of frequency. The phase represents fifty percent of the information so it is most important to measure phase for vibration monitoring. Most vibrations on a rotating machine…

## Average Waterfalls Or Average Orders?

[latexpage]One would expect that averaging waterfalls and then extracting orders would give the same result as extracting orders from individual waterfalls and then averaging them. This is not the case.

## What Is A Fourier Transform?

A Fourier Transform takes a signal and represents it either as a series of cosines (real part) and sines (imaginary part) or as a cosine with phase (modulus and phase form). As an illustration we will look at Fourier analysing…

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