Irregular array motion and extended integration for the suppression of spatial aliasing in passive sonar
| Autor: | Enson Chang |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Synthetic aperture radar
Time delay and integration Sound Spectrography Time Factors Acoustics and Ultrasonics Aperture Computer science Acoustics Transducers Plane wave Sonar Motion Acceleration Arts and Humanities (miscellaneous) Aliasing Synthetic aperture sonar Ultrasonics Radar Noise (signal processing) Reproducibility of Results Signal Processing Computer-Assisted Models Theoretical Uncorrelated Deconvolution Artifacts Algorithms |
| Zdroj: | The Journal of the Acoustical Society of America. 129:765-773 |
| ISSN: | 0001-4966 |
| DOI: | 10.1121/1.3531811 |
| Popis: | Conventional synthetic aperture processing uses motion of the sonar to increase aperture size and bearing resolution. Two recent papers discussed a different application in which synthetic elements are used to fill in an otherwise sparse passive array. This paper points out that ambiguities persist, even with synthetic elements, in the ideal case of a straight, uniform, sparse line array with constant velocity in the presence of plane wave signals. It is also shown that irregular motion such as acceleration introduces additional information which can be exploited to suppress the ambiguities. The degree of suppression in such an approach is independent of signal direction. If source stability supports extended coherent integration, then the acceleration and integration time required are both modest to achieve interesting levels of suppression. For a less stable source, a modified conventional beamformer is introduced which leverages acceleration over multiple snapshots to suppress the ambiguities. A post-beamformed processing stage involving a nonlinear deconvolution technique such as the CLEAN algorithm can further improve the result. A semi-coherent adaptation of CLEAN is shown to remove the residual ambiguities effectively in the presence of a moderate level of uncorrelated noise. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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