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Proceedings Paper

Enhancing acoustic signal quality by rapidly switching between pulse-echo and through-transmission using diplexers
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Paper Abstract

The increase of terrorism and its global impact has made the screening of the contents of liquid-filled containers a necessity. The ability to evaluate the contents of a container rapidly and accurately is a critical tool in maintaining global safety and security. Due to the immense quantities and large variety of containers shipped worldwide, there is a need for a technology that enables rapid and effective ways of conducting non-intrusive container inspections. Such inspections can be performed utilizing "through-transmission" or "pulse-echo" acoustic techniques, in combination with multiple frequency excitation pulses or waveforms. The challenge is combining and switching between the different acoustic techniques without distorting the excitation pulse or waveform, degrading or adding noise to the receive signal; while maintaining a portable, low-power, low-cost, and easy to use system. The Pacific Northwest National Laboratory (PNNL) has developed a methodology and prototype device focused on this challenge. The prototype relies on an advanced diplexer circuit capable of rapidly switching between both "through-transmission" and "pulse-echo" detection modes. This type of detection requires the prototype to isolate the pulsing circuitry from the receiving circuitry to prevent damage and reduce noise. The results of this work demonstrate that an advanced diplexer circuit can be effective; however, some bandwidth issues exist. This paper focuses on laboratory measurements and test results acquired with the PNNL prototype device as applied to several types of liquid-filled containers. Results of work conducted in the laboratory will be presented and future measurement platform enhancements will be discussed.

Paper Details

Date Published: 8 April 2008
PDF: 8 pages
Proc. SPIE 6934, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2008, 693414 (8 April 2008); doi: 10.1117/12.776427
Show Author Affiliations
Juan D. Valencia, Pacific Northwest National Lab. (United States)
Aaron A. Diaz, Pacific Northwest National Lab. (United States)
Brian J. Tucker, Pacific Northwest National Lab. (United States)

Published in SPIE Proceedings Vol. 6934:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2008
Peter J. Shull; H. Felix Wu; Aaron A. Diaz; Dietmar W. Vogel, Editor(s)

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