Browsing by Subject "Ultrasonic range measurement"

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Open Access
Fast processing techniques for accurate ultrasonic range measurements
(Institute of Physics Publishing, 2000) Barshan, B.
Four methods of range measurement for airborne ultrasonic systems - namely simple thresholding, curve-fitting, sliding-window, and correlation detection - are compared on the basis of bias error, standard deviation, total error, robustness to noise, and the difficulty/complexity of implementation. Whereas correlation detection is theoretically optimal, the other three methods can offer acceptable performance at much lower cost. Performances of all methods have been investigated as a function of target range, azimuth, and signal-to-noise ratio. Curve fitting, sliding window, and thresholding follow correlation detection in the order of decreasing complexity. Apart from correlation detection, minimum bias and total error is most consistently obtained with the curve-fitting method. On the other hand, the sliding-window method is always better than the thresholding and curve-fitting methods in terms of minimizing the standard deviation. The experimental results are in close agreement with the corresponding simulation results. Overall, the three simple and fast processing methods provide a variety of attractive compromises between measurement accuracy and system complexity. Although this paper concentrates on ultrasonic range measurement in air, the techniques described may also find application in underwater acoustics.
Open Access
Ultrasonic surface profile determination by spatial voting
(IEEE, 2001) Barshan, Billur
A novel spatial voting scheme is described for surface profile determination based on multiple ultrasonic range measurements. Spatial voting relies on the number of votes accumulated in each pixel of the ultrasonic arc map but ignores neighboring relationships. This approach is extremely robust, flexible, and straightforward. It can deal with arbitrary numbers and configurations of sensors as well as synthetic arrays, with the intrinsic ability to suppress spurious readings, crosstalk, and higher-order reflections, and process multiple reflections informatively. The performance of the method is investigated on various examples involving both simulated and experimental data. The effect of varying the surface roughness is also considered.