1999 Projects: ROV improvements
Spread-spectrum underwater navigation
Improved capability of MBARIs ship navigation systems will benefit many research missions as more accurate positioning information makes the task of finding a specific site, or returning to it, more efficient. Likewise, improving the effective range and accuracy of MBARIs shipboard-mounted navigation systems will decrease the number of times the long baseline system (LBL) will need to be deployed, resulting in a significant decrease in time at sea spent deploying, calibrating, and recovering the LBL system.
Spread-spectrum techniques have been used in many advanced tracking systems, including most NASA space missions, the Global Positioning System, and most of the U.S. Navy underwater tracking systems installed over the last 15 years. Optimal estimation techniques have also been used to improve the performance of navigation systems, particularly in aided inertial navigation. For a number of reasons these techniques have not been used in any systems commercially available today. The goal of this project is to implement these modern processing techniques with commercially available hardware to produce an underwater navigation system with improved range and accuracy over commercially available systems.
MBARIs 1998 spread-spectrum navigation project is developing an analytical model
for an advanced underwater tracking system using spread-spectrum signaling techniques and
optimal estimation of ship attitude. Results to date indicate potential advantages in
pursuing this approach. Spread-spectrum signaling offers significantly better
probabilities of detection at low signal-to-noise ratios and more accurate time-of-arrival
measurements. The optimal estimation work is primarily aimed at reducing the variance in
ship attitude measurements, which are a significant error source at 4,000-meter depths
where MBARIs ROV Tiburon will be operating. In 1999 we will convert the
non-real time, desktop model under development into a real-time, field prototype. The plan
is to port the current model, developed as a Matlab script, to C/C++ code running on a
commercial array processor. Since Matlab is a well-known software prototyping tool,
several array processor vendors support this process. In order to reduce the resource
requirements of this project, we have chosen to subcontract much of the porting process to
the array processor vendor.
Last updated: 07 October 2004