Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1992An ultra-short baseline acoustic navigation system has been developed which is
capable of determining bearing to a sound source with an error of less than 1° in typical
operational conditions. The system has a demonstrated ability to operate in an environment
in which multipath interference is significant. A DSP microprocessor is used to process
signals received by two hydrophones from a 26 kHz toneburst sound source. This
processing power is used to implement features not commonly available with commercial
systems. The system has the capability to make an on-line measurement of the signal-tonoise
ratio, which can be used to estimate the confidence which should be placed in the
data. Estimates of phase difference and signal power are generated many times within each
received pulse, so the effects of multi path interference throughout the pulse can be
observed. Results of tests at several ranges are presented, and compared to performance
models developed in the thesis. System performance is quantified, and an effort is made to
understand the effects of multipath arrivals
