This thesis presents methods for improving the detection processing of active sonar systems. Measures to compensate for or even exploit particular characteristics of the detection problem for these systems are considered. Reverberation is the result of scattering of the transmitted signal from non-target features. Multipath and variability are particularly pronounced for underwater sound signals because propagation is very sensitive to spatial and temporal temperature variations. Another problem is the low pulse repetition rate due to the relatively low speed of sound. This low data rate reduces tracking and detection performance. / Reverberation often arises as the sum of many small contributions so that received data has a multivariate Gaussian distribution. Estimating the large numbers of parameters in the distribution requires a lot of data. This data is not available because of the low data rate. Representing the scattering as an autoregressive process reduced the data requirement but at some cost to modelling accuracy. A coupled estimator algorithm is developed to estimate the parameters. Detection performance is compared to other models and estimators that assume Gaussian statistics. / To counter multipath distortion the delays and strength of the paths are estimated using a version of the expectation maximisation (EM) algorithm. The magnitude of path amplitudes is then used to decide if a target is present. The EM algorithm is also suggested as a way to find the likely amplitude of reverberation from a few large scatterers that that form non-Gaussian reverberation. / Non-parametric methods are considered for detection of short duration incoherent signals in a duct. These detectors compare the ranks of the data in a region being tested for target present to another region assumed to have no target. Simulations are used to explore performance and what happens when the independent samples assumption is violated by the presence of reverberation. / More data can improve detection. Exploiting data from multiple transmissions is difficult because the slow speed of sound allows targets to move out of detection cells between transmissions. Tracking the movements of potential targets can counter this problem. The usefulness of Integrated Probabalistic Data Association (IPDA), which calculates a probability of true track as well as track properties, is considered as a detection algorithm. Improvements when multiple receivers are used as well as limitations when sensor positions are uncertain are investigated.

Thesis (Ph.D.)--University of Wollongong, 2003. / Typescript. Bibliographical references: leaf 461-470.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 83-86).

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). "February 2007." Includes bibliographical references (p. [85]-88). Also available via the World Wide Web.

Thesis (Master of Business Administration)--Naval Postgraduate School, June 2009. / Thesis Advisor(s): San Miguel, Joseph G. "June 2009." Description based on title screen as viewed on July 14, 2009. Author(s) subject terms: software reuse, reuse, ASW software, sonar, fire control, APB, ARCI. Includes bibliographical references (p. 97-100). Also available in print.

Th. doct.--Electronique et communications--Paris--ENST, 1994. / Bibliogr. p. 143-146.

Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, Sept. 2004. / Thesis Advisor(s): Don Brutzman. Includes bibliographical references (p. 221-223). Also available online.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. "Diel activity and vertical distribution of yellow perch ... under the ice," by Gary L. Hergenrader and Arthur D. Hasler inserted between leaves 15 and 16. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Dissertation (Ph.D. in Computer Science) Naval Postgraduate School, December 1994. / "December 1994." Dissertation supervisor(s): Michael J. Zyda. Appendix G videotape located at VHS 5000052. Includes bibliographical references (p. 238-262). Also available online.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Anthony J. Healey. Includes bibliographical references (p. 79). Also available online.