Passive localization of underwater acoustic beacons
Wojcik, Dennis M.
This thesis examines the use of a single, omnidirectional hydrophone as a
receiving sensor to passively localize an acoustic beacon. The localization problem is
presented as a constrained, nonlinear parameter estimation problem, and Lagrange
multipliers are introduced to solve for the maximum likelihood estimate of the acoustic
beacon's position. An iterative algorithm is developed using range difference
measurements to solve for the maximum likelihood estimate of a stationary acoustic
beacon's position. This algorithm is then _extended to include linear, constant velocity
motion of the acoustic beacon. Finally, design specifications for a receiver to
implement the maximum likelihood estimation algorithms are developed.
To test the maximum likelihood estimate algorithms, Monte Carlo simulations
are conducted. Results from six representative scenarios are presented. Test results
show that as the number of range differences used increases, or the distance that the
observer travels between received beacon signals increases, the accuracy of the
estimated position improves. Also, tests show that accuracy of the estimated beacon
position is directly related to the accuracy in which the observer's position is
measured. To test the receiver's design specifications, a prototype receiver is built
using commonly available components. It is then shown that the prototype receiver
meets or exceeds the design specifications.