期刊
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
卷 154, 期 1, 页码 141-151出版社
ACOUSTICAL SOC AMER AMER INST PHYSICS
DOI: 10.1121/10.0020053
关键词
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Direction-of-arrival estimation is challenging for spatially undersampled signals, but frequency-difference beamforming offers an alternative approach. However, unconventional beamforming sacrifices spatial resolution, making it difficult to distinguish closely spaced targets. To overcome this limitation, a simple yet effective method is proposed by formulating frequency-difference beamforming as a sparse signal reconstruction problem. The proposed compressive frequency-difference beamforming outperforms the conventional method in terms of separation when the signal-to-noise ratio exceeds 4 dB, as supported by ocean data from the FAF06 experiment.
Direction-of-arrival estimation is difficult for signals spatially undersampled by more than half the wavelength. Frequency-difference beamforming [Abadi, Song, and Dowling (2012). J. Acoust. Soc. Am. 132, 3018-3029] offers an alternative approach to avoid such spatial aliasing by using multifrequency signals and processing them at a lower frequency, the difference-frequency. As with the conventional beamforming method, lowering the processing frequency sacrifices spatial resolution due to a beam broadening. Thus, unconventional beamforming is detrimental to the ability to distinguish between closely spaced targets. To overcome spatial resolution deterioration, we propose a simple yet effective method by formulating the frequency-difference beamforming as a sparse signal reconstruction problem. Similar to compressive beamforming, the improvement (compressive frequency-difference beamforming) promotes sparse nonzero elements to obtain a sharp estimate of the spatial direction-of-arrival spectrum. Analysis of the resolution limit demonstrates that the proposed method outperforms the conventional frequency-difference beamforming in terms of separation if the signal-to-noise ratio exceeds 4 dB. Ocean data from the FAF06 experiment support the validity.
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