Experimental demonstration of low signal-to-noise ratio matched field processing with a geoacoustic model extracted from noise

Passive localization of a low signal-to-noise ratio (SNR) source in a shallow water waveguide without prior geoacoustic information is accomplished by combining the mode-extraction method modal-MUSIC (multiple signal classification) with range-coherent matched field processing (MFP). Range-coherent MFP coherently combines snapshots from different resolution cells to obtain gain over noise. Modal-MUSIC uses knowledge of the water column sound speed profile (no bottom information) to extract noisy estimates of modal wavenumbers from ship noise recorded on a partially spanning vertical line array (VLA). A geoacoustic model is then fit to the wavenumber estimates extracted from noise with modal-MUSIC and used to compute replicas for range-coherent MFP. The combination of these two methods applied to a 21-element VLA achieves successful source localization at SNR levels as low as -20 dB using ten tonals transmitted during the SWellEx96 experiment.

Automated summary

Passive localization of low SNR sources in shallow water waveguide is achieved by combining modal-MUSIC with range-coherent MFP. Modal-MUSIC extracts noisy estimates of modal wavenumbers from ship noise recorded on a vertical line array. Geoacoustic model is fitted to the wavenumber estimates and replicas are computed for range-coherent MFP. Successful localization is achieved at SNR levels as low as -20 dB using a 21-element VLA and ten tonals transmitted during the SWellEx96 experiment.