Sidelobe suppression of Barker codes via MRH method

Area of Science:

• Non-destructive testing
• Ultrasonic testing
• Signal processing

Background:

• Barker codes are standard in ultrasonic testing for energy enhancement and pulse compression.
• Inherent sidelobes in Barker codes can mask defect echoes in challenging environments.
• Existing methods struggle with signal-to-noise ratio (SNR) degradation in high-scattering materials.

Purpose of the Study:

• To develop a novel signal processing method to overcome Barker code sidelobe limitations.
• To improve defect detection in ultrasonic testing, especially in coarse-grained materials.
• To enhance the signal-to-noise ratio (SNR) beyond conventional matched filtering.

Main Methods:

• A combined processing method (MRH) integrating matched filtering, Richardson-Lucy (RL) deconvolution, and high-pass filtering was developed.
• A symmetrized point spread function (PSF) was constructed as a prior for the RL algorithm.
• The method was validated through simulations and experimental testing on coarse-grained materials.

Main Results:

• Simulations showed the MRH method significantly outperforms conventional matched filtering in SNR across various noise levels.
• Experimental validation on coarse-grained materials demonstrated substantial SNR improvement for back-wall echoes (22.07 dB to 45.23 dB).
• The MRH method effectively suppresses sidelobes and enhances detection in high-scattering environments.

Conclusions:

• The proposed MRH method is effective in suppressing sidelobes and improving SNR in ultrasonic testing.
• This technique shows significant promise for defect detection in challenging materials like coarse-grained metals.
• Future research will focus on integrating neural networks for enhanced efficiency and broader applicability to other coded sequences.