Prosig Noise & Vibration Blog

Noise & Vibration Capture with GPS Tracking

Chris Mason — Tue, 16 Mar 2010 16:04:45 +0000

The latest version of the CAN-bus/GPS (8440) module is now available for the Prosig P8012, P8020 and P8048 systems. The CAN-bus/GPS module has been in use in the field for some time now, recording CAN-bus information for display and analysis alongside noise, vibration, temperature and other signals captured by P8000 [...]

Comparison Between Sound Intensity Probes and Acoustic Cameras

James Wren — Mon, 15 Mar 2010 12:58:37 +0000

Sometimes we are asked about the differences between an acoustic camera and a sound intensity probe and which of the two is better for a particular application. There is no straightforward answer as they are quite different pieces of equipment, used for measuring different things. An acoustic camera is a tool used to locate and [...]

Prosig launch new PROLOG data acquisition controller

Chris Mason — Tue, 19 Jan 2010 09:43:33 +0000

Prosig have welcomed 2010 with the official launch of their PROLOG data acquisition controller.

PROLOG is a controller that will allow remote, unattended or standalone operation of a P8000 system. In normal operation a P8000 data acquisition system is connected to a laptop or PC and data is stored, in real-time, on the computers hard drive via the USB 2.0 [...]

What is the difference between microphone types?

James Wren — Tue, 19 Jan 2010 09:43:17 +0000

I’m often asked what is the difference between free field microphones, diffuse field microphones and pressure microphones.

For a run-of-the-mill ½ inch microphone the short answer is nothing.

However the long answer is a bit more involved.

Basically if the sample rate is 10 kHz or below and an accuracy of ±2dB is acceptable then there is no [...]

A Simple Frequency Response Function

James Wren — Mon, 19 Oct 2009 08:39:02 +0000

The following article will attempt to explain the basic theory of the frequency response function. This basic theory will then be used to calculate the frequency response function between two points on a structure using an accelerometer to measure the response and a force gauge hammer to measure the excitation.

Fundamentally a frequency response function is [...]

Amplitude And Energy Correction – A Brief Summary

John Mathey — Tue, 01 Sep 2009 10:44:01 +0000

In this article we will look at why we need to consider energy correction when producing frequency spectra and how we go about it. We will use a perfect, ’special case’ signal to keep the explanation as simple as possible. The signal we will use is periodic within the time record used to calculate the [...]

Data Windows : What, why and when?

John Mathey — Mon, 20 Jul 2009 08:23:53 +0000

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 time signal must equal the energy measured on the frequency representation of that signal. Second, an FFT [...]

Interpolation Versus Resampling To Increase The Sample Rate

Dr Colin Mercer — Mon, 22 Jun 2009 14:12:21 +0000

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 classical curve fitting procedure to obtain a better representation.

As a second example we will look at [...]

10 Great Fourier Transform Links

Chris Mason — Wed, 22 Apr 2009 13:03:00 +0000

Following a discussion in the office about Fourier Transforms we did a little searching on the web. As always, we discovered that the Internet is packed with some great resources on Fourier and his work. So rather than keep all of the information to ourselves we thought we should share it with our readers. We [...]

Measurement And Analysis Of Torsional Vibration

Adrian Lincoln — Fri, 17 Oct 2008 07:44:13 +0000

Torsional vibration is of key importance in the area of vehicle development and refinement. The main contributory source is the engine where periodically occurring combustion cycles cause variation in the crankshaft rotary vibration. This vibration is transmitted to and modified further by other components in the powertrain such as the gearbox and by other equipment [...]

Strain Gauges Explained

James Wren — Mon, 08 Sep 2008 08:21:06 +0000

A strain gauge is an electrical sensor which is used to accurately measure strain in a test piece. Strain gauges are usually based on a metallic foil pattern. The gauge is attached to the test piece with a special adhesive. As the test piece is deformed, so the adhesive deforms equally and thus the strain [...]

Prosig Awarded Contract To Upgrade Online Vibration Monitoring System At Wylfa

Don Davies — Fri, 05 Sep 2008 08:55:35 +0000

Prosig have been awarded the contract to upgrade the Online Vibration Monitoring System at Wylfa nuclear power station.

Wylfa is located on the north coast of Anglesey and has two Magnox design nuclear reactors and four turbine generators. The station supplies 23 million kilowatt hours of electricity, enough to meet the needs of two [...]

Shaft Displacement Measurement Using A PROTOR System

Don Davies — Wed, 04 Jun 2008 10:49:36 +0000

Shaft displacement is an important vibration measurement for rotating machines. Shaft displacement is usually monitored by non-contact shaft displacement probes such as eddy-current probes. These probes produce a voltage proportional to the distance of the shaft surface relative to the tip of the probe. For maximum benefit, ideally two shaft displacement probes will be fitted [...]

What Are dB, Noise Floor & Dynamic Range?

James Wren — Mon, 14 Apr 2008 11:58:49 +0000

Most engineers are probably familiar with or have come across the decibel or dB as a unit of measurement. Its most common use is in the field of acoustics where it is used to quantify sound levels. However, as will be explained in this article, it is also useful for a wide variety of measurements [...]

Prosig Power Units Offer New Levels Of Flexibility

James Wren — Tue, 25 Mar 2008 10:02:45 +0000

The size and shape of the Prosig P8000 data acquisition systems greatly facilitates installation in locations that are small or difficult to access. Now Prosig can offer a new level of flexibility. Not only can the P8000 be used in the laboratory and in the automobile, but with the new mobile Prosig Power units [...]

Vibration Monitoring Phase Measurement And The Tacho Signal

Dr Colin Mercer — Tue, 04 Mar 2008 09:52:09 +0000

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 are related to the rotational speed so it is clearly important to have a measure [...]

Human Exposure To Vibration In Buildings (DIN 4150-2:1999-06 & DIN 45669-1:1995-06)

Dr Colin Mercer — Fri, 30 Nov 2007 09:35:44 +0000

Standards DIN 4150-2:1999-06 and DIN 45669-1:1995-06 provide a means of assessing the effect on human beings of vibration caused by vehicle traffic, trains both above and below ground, construction work and occasional impulsive type vibration caused by, say, blasting and the like.

DIN 45669-1 describes the signal processing actions and DIN 4150-2 details how these are [...]

Orders v Time – Comparing Overall Levels

Dr Colin Mercer — Tue, 23 Oct 2007 13:33:06 +0000

By combining a speed signal with a data signal and using the Short Time FFT algorithm (Hopping FFT), it is possible to extract order data directly as a function of time (Orders from Hopping FFT) rather than as a function of speed (Waterfall). This is very useful when analyzing a complete operational cycle which includes [...]

Calculating Velocity Or Displacement From Acceleration Time Histories

Adrian Lincoln — Fri, 05 Oct 2007 10:56:53 +0000

It is quite straightforward to apply “classical” integration techniques to calculate either a velocity time history from an acceleration time history or the corresponding displacement time history from a velocity time history.

The standard method is to calculate the area under the curve of the appropriate trace. If the curve follows a known deterministic function then [...]

Sound Steering

Dr Colin Mercer — Wed, 12 Sep 2007 09:54:20 +0000

The requirement was to develop a ‘standard’ test for assessing the sound quality of power steering pumps in vehicles. Measurements needed to be objective so that the method would be suitable for evaluating dissimilar vehicles and different types of pump.

Noise is an important consideration when a consumer is selecting a new vehicle. It is therefore [...]