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Published on: February 6, 2014
The feasibility of pulse compression by nonlinear effective bandwidth extension
Gregory T Clement1, Hideyuki Nomura, Tomoo Kamakura
1Department of Radiology, Harvard Medical School and Brigham & Women's Hospital, Boston, Massachusetts 02115, USA. gclement@hms.harvard.edu
The Journal of the Acoustical Society of America
|October 7, 2011
Summary
This study introduces extended bandwidth signal compression by combining fundamental and higher harmonics, significantly improving signal-to-noise ratio (SNR) and resolution in chirp imaging.
Area of Science:
- Acoustic imaging
- Signal processing
- Ultrasound technology
Background:
- Chirp-encoded excitation enhances signal-to-noise ratio (SNR) in linear and harmonic imaging.
- Conventional methods require isolating specific frequency bands, which can introduce artifacts.
Purpose of the Study:
- To develop a novel method for signal compression using an extended bandwidth.
- To simultaneously improve SNR and signal resolution in chirp imaging.
Main Methods:
- Isolating and combining fundamental and higher harmonics into a single extended bandwidth.
- Utilizing pulse-inverted sum and difference signals to isolate even and odd harmonics.
- Applying matched filters specific to source geometry and transmit signal for each harmonic band.
Main Results:
- Extended bandwidth compression demonstrated increased compression compared to fundamental and second harmonic methods.
- Third harmonic bands achieved a mean pulse width of 56% relative to fundamental and 48% relative to second harmonic compression.
- Optimization resulted in a 17% pulse width reduction and a 47% increase in peak-to-sidelobe ratio.
Conclusions:
- Extended bandwidth signal compression is feasible for simultaneous SNR and resolution enhancement.
- This technique offers a significant advancement over existing chirp compression methods.
- The approach holds promise for various applications in acoustic imaging and signal processing.
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