Determining the sensitivity of measured acoustic quantities on variability in geophysical and oceanographic conditions

Abstract

Sonar is used to remotely investigate the underwater environment and to detect and track vessels therein, either by their own acoustic emissions or through scattering from active transmission. The acoustic signals available to an observer are a function of the transmitter’s relative position, course, and signature, and the local environment. In order to make effective use of the received acoustic signals, an observer requires a thorough understanding of the propagation and scattering characteristics of the overall underwater environment as well as the implications of those characteristics on the analysis techniques applied to the received signals. Defense R&D Canadas (DRDC) Rapid Environmental Assessment (REA) Program aims to provide a capability for accumulation and interpretation of environmental information in a tactical timeframe. A main objective of the REA program is to explore the nature of geophysical and oceanographic variability and to quantify its effect on acoutic signals. This effect is analyzed via modeling and through the use of data from the joint DRDC/NURC sea trial BASE 04 (Broadband Acoustic Sonar Experiment 2004). This trial, which took place in May and June of 2004 in the Malta Plateau and Medina Bank areas, included several experiments measuring active sonar propagation in an uncertain environment.