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Eliminating harmonic interference in frequency domain multiplexed quasi-distributed ultrasonic sensing with
Optics Letters
|April 15, 2026
Summary
A new bidirectional linear frequency sweep (LFS) method suppresses harmonic interference in quasi-distributed acoustic sensing (QDAS). This improves ultrasonic detection accuracy for non-destructive testing and imaging applications.
Area of Science:
- Acoustic Sensing
- Signal Processing
- Non-Destructive Testing
Background:
- Harmonic interference limits accuracy in frequency division multiplexed quasi-distributed acoustic sensing (FDM-QDAS).
- Accurate ultrasonic detection is crucial for non-destructive testing and imaging.
Purpose of the Study:
- To introduce a novel multiplexing scheme to suppress harmonic interference in FDM-QDAS.
- To enhance the accuracy and performance of QDAS for ultrasonic measurements.
Main Methods:
- Developed a bidirectional linear frequency sweep (LFS) multiplexing scheme.
- Leveraged distinct cross-correlation properties of forward and backward LFS signals.
- Experimentally validated the scheme with submerged single-frequency signals and 1 MHz ultrasonic pulses.
Main Results:
- Successfully suppressed harmonic interference.
- Recovered submerged single-frequency signals with high fidelity.
- Demodulated narrow (10 μs width) ultrasonic pulses propagating on a metal plate.
Conclusions:
- The bidirectional LFS scheme effectively suppresses harmonics in FDM-QDAS.
- This method enables high-fidelity measurement of narrow acoustic pulses without sacrificing bandwidth.
- Significantly advances QDAS performance for ultrasonic non-destructive testing and imaging.
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