Broadband sparse-array blind deconvolution using frequency-difference beamforming.

Shima H Abadi, H C Song, David R Dowling

Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA. shimah@umich.edu

The Journal of the Acoustical Society of America 2012 Nov

filter terms:

acoustics (1)

equipment design (1)

fourier transforms (2)

models theoretical (1)

motion (1)

sound (3)

sound spectrography (1)

time factors (1)

transducers (1)

Sizes of these terms reflect their relevance to your search.

Synthetic time reversal (STR) is a technique for blind deconvolution of receiving-array recordings of sound from an unknown source in an unknown multipath environment. It relies on generic features of multipath sound propagation. In prior studies, the pivotal ingredient for STR, an estimate of the source-signal's phase (as a function of frequency ω), was generated from conventional beamforming of the received-signal Fourier transforms, P(j)(ω), 1 ≤ j ≤ N, where N is the number of array elements. This paper describes how STR is implemented even when the receiving-array elements are many wavelengths apart and conventional beamforming is inadequate. Here, the source-signal's phase is estimated by beamforming P(j)(*)(ω(1))P(j)(ω(2)) at the difference frequency ω(2) - ω(1). This extension of STR is tested with broadband signal pulses (11-19 kHz) and a vertical 16-element receiving array having a 3.75-m-spacing between elements using simple propagation simulations and measured results from the FAF06 experiment involving 2.2 km of down slope propagation from 46 to 92 m water depth. The cross-correlation coefficient between the source-broadcast and STR-reconstructed-signal waveforms for the simulations and experiments are 98% and 91%-92%, respectively. In addition, frequency-difference beamforming can be used to determine signal-path-arrival angles that conventional beamforming cannot.

Citation

Shima H Abadi, H C Song, David R Dowling. Broadband sparse-array blind deconvolution using frequency-difference beamforming. The Journal of the Acoustical Society of America. 2012 Nov;132(5):3018-29