Effects Of Boundary Variability On The Statistics Of Received Signal Parameters

Open Access
Author:
Joseph, Jeremy Matthew
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Lee Culver, Thesis Advisor
  • Richard Lee Culver, Thesis Advisor
Keywords:
  • underwater acoustics
Abstract:
Underwater acoustic propagation introduces significant variability in the received signal through time-varying rough surface and bottom scattering as well as volume inhomogeneities. This work considers specifically the variability introduced by time-varying rough surface scattering and its effects on signal frequency and amplitude statistics. An acoustic propagation code built upon the parabolic wave equation (PE) is used to model such surface scattering in the ocean. Low frequency propagation in shallow water environments is of interest and modeled with the use of simulation. Using a temporally evolving rough surface, frequency and amplitude statistics are calculated for an environment over a time progression. The simulation is run under different wind speeds and source frequencies with receivers at several ranges and depths. The predicted effects of scattering on the statistics of received signal parameters are compared with published analytical and empirical models, primarily those from Dyer’s work. In simulation, no depth dependence is observed in received signal frequency spectra. Results from simulation also suggest that the variance in received signal frequency spectra is constant and independent of wind speed. Finally, transmission loss distributions are found to be similar to Dyer’s prediction at moderately low frequencies, longer ranges, and with increasing wind speed.