Abstract:
When designing signal processors to discriminate against underwater sound background noise and scattering, it is important to know the statistics of the unwanted signal disturbances. A study was undertaken for the Naval Research Laboratory, Stennis Space Center, Mississippi to review the literature reporting on a number of bottom scattering experiments that were conducted during the past 15--20 years. The scope of the investigation is limited to high frequencies (10 to 200 kHz) and shallow water of depths less than 100 m. Many of these tests were performed by the Naval Research Laboratory, Stennis Space Center; the Applied Research Laboratories, University of Texas at Austin; and the Applied Physics Laboratory, University of Washington. Other experiments reviewed were performed by Thomson-Sintra ASM, France and by the University of Wisconsin. Each experiment will be briefly described, and the statistical results discussed and summarized for various parameters, such as frequency, beamwidth, pulse length, grazing angle, range, and environmental factors. The statistic that was primarily examined was the probability of false alarm. The PFAs were found to follow a number of probability distribution functions including Gaussian, Rayleigh, log-normal, etc. The PFAs were quantified to systematically determine any trends with the parameters.