Performance and Progress Report - John Doe FIX: put in the authors ...

The next stage in the development of this project is the application of statistical tools for
counting fish using high resolution multibeam backscatter. This method, which was
originally applied to counting fish using single beam echo sounders, differs from the
more traditional echo integration methods in that it does not require absolute target
strengths and is insensitive to target orientation. The method is essentially based on the
scintillation of backscatter from fish and shows much promise for high resolution echo
sounding sonars, including most multibeam sonars. It is hoped that the Georges Bank
herring data (both 7125 and EK60) can be used to test this methodology.
AUV WORK AND THE HARBOR TRACKING AND
OBSERVATORY PROJECT:
In our ongoing effort to explore new approaches to collect hydrographic and other data in
critical shallow water environments, we have begun to explore the applicability of using a
small Autonomous Underwater Vehicle for collecting critical bathymetric and other data.
We have teamed with Art Trembanis of the University of Delaware to obtain use of his
FETCH 3 vehicle. We have purchased and integrated small multibeam sonar (Imagenix
Delta-T) into this AUV and have begun to explore its applicability for collecting both
hydrographic quality bathymetric data and seafloor characterization data. At this point in
time we have only had a several days of interaction with the vehicle but we are now in
the process of calibrating the sonar and developing control and visualization software for
the vehicle. In support of this effort as well as to provide a permanent ability to
accurately position this (or any other) AUV as well as cameras, samplers and other
devices we have begun a project designed to install a fixed acoustic navigation array in a
portion of Portsmouth Harbor. When fully functional, this positioning system may also
provide the ability to passively listen to ship-traffic in the harbor as well as to monitor
changes in the physical oceanography of the harbor. We have called this component of
the project the “Harbor Observatory Project.”
Our effort this year has been two-pronged: 1) conducting a study to evaluate COTS
hardware for accomplishing this task and 2) developing a home-grown proof-of-concept
system. So far our discussions with commercial vendors have led us to believe that there
is not a simple COTS solution and thus most of our effort has been focused on
developing the proof-of-concept system. This system, whose development is under the
supervision of Tom Weber (with collaboration from McGillicuddy, Huff,
Weirathmueller, Schmidt, Calder and Mayer) is based on a bearing-bearing system and is
essentially a hybrid between an ultra-short baseline system and a long baseline system.
We have built a proof-of-concept system (including design and construction of preamps,
assembly of hydrophone system, and integration with a data acquisition system) that
demonstrates a remarkably accurate bearing measuring capability (σθ ~ 0.1°) in tank
testing.
A field test of this system (conducted with the help of the Coastal Surveyor and Ben
Smith, Michelle Weirathmueller, Val Schmidt, Andy McLeod, and Kurt Schwehr) was
conducted in August at the old Coast Guard pier in Portsmouth Harbor. Although data
analysis from this experiment is still underway, initial results show that the system
JHC Performance Report 52 30 January 2007