Measurement of mechanical vibrations using eddy current transducers and simple digital demodulating techniques

A coil with a soft magnetic ferrite core and excited by an AC current is placed near a metallic vibrating object. The impedance of the coil is influenced by the vibrations, so the voltage across the impedance is composed of a carrier voltage signal modulated by the mechanical vibrations. The produce...

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Bibliographic Details
Published in:IEEE transactions on industrial electronics (1982) 1988-02, Vol.35 (1), p.135-140
Main Authors: Girgis, G.A., Horn, K., Kruse, G.
Format: Article
Language:English
Subjects:
Applied sciences
Coils
Current measurement
Eddy currents
Exact sciences and technology
Frequency
Impedance
Industrial metrology. Testing
Mechanical engineering. Machine design
Mechanical variables measurement
Soft magnetic materials
Transducers
Vibration measurement
Voltage
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Summary:A coil with a soft magnetic ferrite core and excited by an AC current is placed near a metallic vibrating object. The impedance of the coil is influenced by the vibrations, so the voltage across the impedance is composed of a carrier voltage signal modulated by the mechanical vibrations. The produced signal is processed through a 10 bit analog-to-digital converter, a RAM, and a transient recorder for storing the data. It is found that the calculation of the fast Fourier transform of the quadrature of the stored data of the signal gives a rapid and accurate digital demodulation technique. A Z-80 microcomputer is used for storing and processing the data. A small number of points at the frequency spectrum will give the required unknown values of the amplitude and frequency of the mechanical vibrations.< >
ISSN:0278-0046
1557-9948
DOI:10.1109/41.3076