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A swept frequency multiplication technique for air-coupled ultrasonic NDE
Tat Hean Gan1, David A Hutchins, Roger J Green
1School of Engineering, University of Warwick, Coventry CV4 7AL, UK. t.h.gan@warwick.ac.uk
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
|November 24, 2004
Summary
A novel swept frequency multiplication (SFM) technique enhances air-coupled nondestructive evaluation (NDE) signal quality. This method enables rapid air-coupled imaging by processing signals in the time and frequency domains.
Area of Science:
- Materials Science
- Acoustics
- Non-Destructive Evaluation (NDE)
Background:
- Air-coupled NDE offers advantages for inspecting large or complex structures.
- Current NDE methods can be limited by signal-to-noise ratios and processing time.
- Polymer-filmed capacitive transducers provide wide bandwidth signals suitable for advanced processing.
Purpose of the Study:
- To introduce and evaluate a new signal processing technique for air-coupled NDE.
- To demonstrate the potential of swept frequency multiplication (SFM) for improving signal quality.
- To explore the feasibility of SFM for rapid air-coupled imaging applications.
Main Methods:
- Utilizing a swept-frequency "chirp" signal transmitted via air-coupled transducers.
- Implementing a single time-domain multiplication process to generate a difference frequency signal.
- Isolating the difference frequency signal in the frequency domain for analysis.
Main Results:
- The swept frequency multiplication (SFM) approach effectively processes air-coupled NDE signals.
- The technique allows for easy isolation of the desired signal in the frequency domain.
- Demonstrated potential for significantly improving signal quality in air-coupled NDE.
Conclusions:
- The new SFM technique shows promise for enhancing air-coupled NDE.
- SFM offers a pathway towards achieving rapid and high-quality air-coupled imaging.
- This method represents a significant advancement in NDE signal processing.