On the estimation of source location using a passive towed array
The passive estimation of the location of narrow-band acoustic sources using line arrays of equispaced hydrophones is considered in this thesis. In particular, when it is assumed that the signal wavefront is planar at the array, the bearing of the source is estimated, and when a spherically curved wavefront is considered, the range and cross-range of the source are estimated. The ability to retrieve source location information is affected by the values of unknown nuisance parameters and additive, uncorrelated noise in the space-time data received by the array. Under various assumptions about the source, the estimation accuracies of different array configurations are compared within the framework of Cramer-Rao lower bound (CRLB) analysis. The CRLBs establish absolute bounds on location estimation variance. A geometric concentration ellipse approach, based upon CRBL analysis, is also used because of its ability to reveal important features about the simultaneous estimation of two parameters. Fixed-posit ion array (FPA), conventional towed array (CTA), and spatially-referenced towed array (SPARTA) configurations are all considered. A SPARTA is a combination of a FPA with a CTA.^ Of particular note in this study are (i) the derivation of many simplified CRLB expressions which serve to provide enhanced insight and understanding; (ii) the introduction of the SPARTA for location estimation when the source frequency is unknown and its demonstrated potential to achieve location estimation accuracy that is greatly improved over that of FPAs and CTAs; (iii) the key role played by the phase differenced between two closely-spaced sources in the ability of arrays to resolve the sources in bearing; and (iv) the amount of loss incurred by arrays to estimate location parameters in the presence of moving sources. ^
Engineering, Electronics and Electrical
Geoffrey S Edelson,
"On the estimation of source location using a passive towed array"
Dissertations and Master's Theses (Campus Access).