Title :
Fast optical LDA burst analyzer
Author_Institution :
DLR-Inst. for Exp. Fluid Mech., Gottingen, West Germany
Abstract :
A method for processing Doppler signals is proposed. The basic idea is to process the signal trace obtained by a transient recorder not numerically, but optically, storing it as an image in a spatial light modulator and obtaining the Fourier transform with the speed of light by the use of coherent laser light. Due to the finite resolution of the transient recorder and the light modulator, the image consists of rows of equally spaced bars. As a result of the Fourier transformation equally spaced dots are obtained. The distance between corresponding dots is proportional to the Doppler frequency to be determined. An experimental setup for testing this new principle is described. Simulated as well as real Doppler bursts are treated. The method is found to be a powerful tool for Doppler burst processing, especially when the signal-to-noise ratio is very poor. The use of a simple algorithm for frequency detection increases the confidence in correct data collection.<>
Keywords :
Doppler effect; Fourier transforms; computerised signal processing; laser velocimetry; optical modulation; spectral analysers; transient analysers; Doppler burst processing; Doppler frequency; Doppler signals; Fourier transform; coherent laser light; computerised signal processing; data collection; finite resolution; frequency detection; optical LDA burst analyzer; signal trace; signal-to-noise ratio; spatial light modulator; transient recorder; Bars; Fourier transforms; Frequency; Image resolution; Linear discriminant analysis; Optical modulation; Optical recording; Signal processing; Signal resolution; Spatial resolution;
Journal_Title :
Aerospace and Electronic Systems Magazine, IEEE
