What Is A Hammer Test Or Hammer Impact Test?

This is often also known as Modal Testing. It is a method of testing that allows us to calculate the natural frequencies (modes), modal masses, modal damping ratios and mode shapes…

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Vibration : Measure Acceleration, Velocity or Displacement?

When using vibration data, especially in conjunction with modelling systems, the measured data is often needed as an acceleration, as a velocity and as a displacement. Sometimes different analysis groups require the measured signals in a different form. Clearly, it is impractical to measure all three at once even if we could. Physically it is nigh on impossible to put three different types of transducer in the same place.

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What Is The Difference Between Single Ended & Differential Inputs?

Prosig data acquisition systems use differential inputs, but what are they and why are they so special? This subject is not always fully understood and, therefore, the focus of this…

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Converting Acceleration, Velocity & Displacement

From time to time I meet engineers who are interested in the conversions between acceleration, velocity and displacement. Often, they have measured acceleration, but are interested in displacement or vice versa. Equally, velocity is often used to find acceleration. This article outlines the nature of the conversion between these units and will suggest the preferred method for doing so. .

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Read more about the article A Simple Frequency Response Function
Figure 5: H1(f)

A Simple Frequency Response Function

The following article will attempt to explain the basic theory of the frequency response function (FRF). 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 FRF is a mathematical representation of the relationship between the input and the output of a system.

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What Are dB, Noise Floor & Dynamic Range?

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 in other fields such as electronics and communications.

One particular use of dB is to quantify the dynamic range and accuracy of an analogue to digital conversion system. This applies to Prosig’s P8000 range of data acquisition hardware where the noise floor, dynamic range and resolution are all specified in terms of dB.

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