SARA/CAATI sonar technology was researched and developed to provide high-resolution imaging and bathymetry capability in a small package suitable for deployment on small autonomous underwater vehicles.This sonar technology proved very successful for a wide variety of applications and is the subject of a patent and three license agreements.The earliest agreement with

This patented sonar technology consists of both a hardware configuration and a software signal processing methodology.The hardware configuration consists of a vertical stack of six horizontally long array elements coupled to a fully coherent multi-channel transmitter/receiver.The physical arrangement of the transmit/receive transducer is such that it can be installed wherever an ordinary side-scan transducer can, yet with the result of obtaining both imagery and bathymetry instead of just imagery.Further, the bottom imagery obtained is not contaminated by surface or water-column targets as it is with side-scan sonars.

The signal processing methodology was developed to estimate angles of arrival of multiple signals received by a small aperture array.Software based on this methodology can accurately estimate multiple angles of arrival in the presence of noise and glint.Previous methods for angle of arrival estimation in the transient signal environment of bathymetric interferometric sonars could estimate only one angle and therefore were ineffective in multi-path environments.Our methodology treats multi-path signals like direct signals and estimates both; therefore, not only do we estimate the direct arrival accurately but we also get a good picture of the entire acoustic environment.The methodology includes a glint filter that effectively removes samples that are distorted by glint (large phase variations across the array caused by unfavourable constructive and destructive interference of signals from multiple scatters).The methodology allows the estimation to be done with transient signals, and a trade-off of resolution and estimation accuracy can be made.