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Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform
Published on: February 12, 2014
Irregular array motion and extended integration for the suppression of spatial aliasing in passive sonar
1EC Analysis, 7012 Clovercliff Drive, Rancho Palos Verdes, California 90275, USA. enson_chang@ecanalys.com
The Journal of the Acoustical Society of America
|March 3, 2011
Summary
This study reveals that while synthetic elements can fill sparse passive arrays, ambiguities persist. Irregular motion, like acceleration, provides crucial information to suppress these ambiguities, enhancing sonar performance.
Area of Science:
- Acoustics and Signal Processing
- Array Signal Processing
- Passive Sonar Systems
Background:
- Conventional synthetic aperture processing enhances sonar resolution using motion.
- Recent work explored synthetic elements to augment sparse passive arrays.
- Ambiguities remain a challenge in sparse linear arrays with constant velocity motion.
Purpose of the Study:
- To identify persistent ambiguities in sparse passive arrays even with synthetic elements.
- To investigate the role of irregular motion, specifically acceleration, in ambiguity suppression.
- To propose methods for improving bearing resolution in passive sonar systems.
Main Methods:
- Analysis of ambiguities in straight, uniform, sparse line arrays with constant velocity.
- Exploitation of information from irregular motion (acceleration) for ambiguity suppression.
- Development of a modified conventional beamformer leveraging acceleration over multiple snapshots.
- Application of nonlinear deconvolution techniques, including a semi-coherent CLEAN algorithm adaptation.
Main Results:
- Ambiguities persist in ideal sparse linear arrays with constant velocity, even with synthetic elements.
- Irregular motion (acceleration) introduces exploitable information for ambiguity suppression, independent of signal direction.
- Modest acceleration and integration time can achieve significant ambiguity suppression for stable sources.
- The modified beamformer and CLEAN algorithm effectively suppress residual ambiguities in moderate noise.
Conclusions:
- Irregular motion is a key factor in overcoming limitations of synthetic aperture processing in sparse arrays.
- Acceleration-based methods offer a viable approach to enhance bearing resolution in passive sonar.
- Advanced processing techniques like CLEAN can further refine results and mitigate noise effects.
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