Low frequency acoustic communication and the waveguide modal behavior during Shallow Water 2006 experiment

Abstract

Low frequency (i.e., <500 Hz) acoustic intensity fluctuations in the presence of internal waves has been studied in some detail during the past two decades. However, not much has been reported on the relationship between the modal behavior of the waveguide and the potential for long-range communications. Previously, we have shown significant performance degradation at higher frequencies (i.e., 800 and 1600 Hz) while an internal wave packet travels through a source-receiver track. Here, we further examine the acoustic transmissions at lower frequencies (i.e., 100 and 200 Hz) during the same internal wave event. Significant intensity fluctuations at these frequencies can be explained by modal analysis. We also report acoustic communication performance at multiple frequencies (i.e., 100, 200, 800, and 1600 Hz). The frequency dependency is analyzed with the focus on modal behaviors to explain the performance variation of acoustic communication during the passage of the internal waves.