Accuracy analysis of major signal processing techniques in laser Doppler velocimetry

2005 ◽  
Author(s):  
Ivan A. Popov
Keyword(s):  
Signal Processing ◽  
Laser Doppler Velocimetry ◽  
Laser Doppler ◽  
Accuracy Analysis ◽  
Doppler Velocimetry ◽  
Processing Techniques ◽  
Signal Processing Techniques

Laser Doppler Velocimetry Signal Processing Based on Spectral Refinement and Correction

2011 ◽  
Vol 383-390 ◽  
pp. 6319-6323
Author(s):  
Nian Long Song ◽  
Da Zhang ◽  
Qi Li
Keyword(s):  
Signal Processing ◽  
Laser Doppler Velocimetry ◽  
Operation Time ◽  
Laser Doppler ◽  
Doppler Signal ◽  
Doppler Velocimetry ◽  
Basic Principles ◽  
Doppler Signals ◽  
Sinusoidal Signals ◽  
Ratio Correction

In order to improve the accuracy of signal processing in Laser Doppler Velocimetry, a method based on the association of spectral refinement and correction is presented. Zoom-FFT and ratio correction are adopted to realize this method. Basic principles of zoom-FFT and ratio correction are expounded. FFT and the method are adopted to process sinusoidal signals and simulated laser Doppler signals with different frequencies separately in circumstance of MATLAB 7.0. Comparisons between the results of FFT and the method are carried out. The comparisons show that this method has the capability to improve the accuracy of laser Doppler signal processing significantly and the operation time is acceptable for LDV system.

A Review of Signal Processing Techniques for Continuous-Scan Laser Doppler Vibrometry

2014 ◽  
Author(s):  
Shifei Yang ◽  
David Ehrhardt ◽  
Matthew S. Allen
Keyword(s):  
Signal Processing ◽  
Periodic System ◽  
Laser Doppler ◽  
Modal Testing ◽  
Laser Doppler Vibrometry ◽  
Velocity Signal ◽  
Processing Techniques ◽  
Scan Pattern ◽  
Time Periodic ◽  
Signal Processing Techniques

A Laser Doppler Vibrometer (LDV) measures the laser Doppler frequency shift and converts it to the velocity at a point of a structure along the laser beam direction. In commercially available scanning LDV, the laser is redirected by a pair of orthogonal mirrors from one point to another, measuring the responses at these points sequentially. Continuous-Scan Laser Doppler Vibrometry (CSLDV) is built on scanning LDV; the laser sweeps continuously over a structure while recording the response along the laser path. The continuous-scan approach can greatly accelerate modal testing, providing spatially detailed vibration shape of the structure at tens or even hundreds of points in the time that is required to measure the vibration at a single point. However, extracting vibration shapes from CSLDV measurements is challenging because the laser spot is continuously moving. This technical difficulty and the equipment cost have become the major barriers that prevent the widespread use of CSLDV. Several algorithms to extract vibration shapes have been developed since CSLDV was introduced. Ewins et al proposed a polynomial approach that treats the vibration shape along the laser scan path as a polynomial function of the laser position. The polynomial coefficients were found from the sideband harmonics in the frequency spectrum of the acquired velocity signal. Allen et al proposed a lifting approach that collects the measured responses at the same location along the laser path. The reorganized measurements appear to be from a set of pseudo transducers attached to the structure. Hence, the well-established conventional modal identification routines can be applied to process CSLDV measurement. Algorithms based on linear time periodic system identification theory were explored as well. These algorithms are based on the fact that the measured velocities along the laser path are the responses of a special liner time periodic system when a closed, periodic laser scan pattern is employed. For the first time, this work compares these signal processing techniques employed in different applications using the same set of data obtained from a cantilever beam. The noise and uncertainty in the reconstructed vibration shapes are discussed in order to present the advantages and disadvantages of each method.

scholarly journals A Microprocessor Based Laser-Doppler Vibration Probe

1984 ◽  
Author(s):  
A. D. Brown ◽  
R. A. Cookson
Keyword(s):  
Signal Processing ◽  
Mechanical Vibration ◽  
Laser Doppler ◽  
Microprocessor System ◽  
Doppler Probe ◽  
Wide Range ◽  
Fibre Optic Probe ◽  
Optic Probe ◽  
Processing Techniques ◽  
Signal Processing Techniques

The laser-Doppler, fibre-optic probe which has been developed at Cranfield and which can be used for the non-intrusive detection and measurement of mechanical vibration, has been improved optically and by the inclusion of a microprocessor system to replace the previously employed frequency tracker and Bragg cells. These improvements facilitate the manufacture of a laser-Doppler probe which is more compact and considerably cheaper than the previous version, and which has potential for the application of a wide range of signal processing techniques.

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