Multi-Static SeaSonde Ocean Current Mapping by Ships Underway

Under the Phase 1 effort, we developed tools that allow us to define system performance when transmitter and/or receiver are installed on vessels underway. These embody the basic physics of multi-static HF sea scatter and radar signal processing. Thetools are used to study tradeoffs of performance vs cost, as well as constraints on vessel maneuvering during surveys. The Phase 2 effort will examine the major risk areas confronting the successful completion of an operational system. This includesdeveloping and demonstrating (by sea trials) the best possible algorithms to extract current maps from vessels underway. The advantage introduced by the ship velocity -- as shown in the Phase 1 Final Report -- is to spread the Bragg Doppler spectral regionthat contains current information into many bins instead of the few that result when transmitter/receiver are stationary (on shore). This offers more bearing angle information that can improve accuracy. Or, this phenomenon can be used in processing toreduce the time span over which the ship velocity must remain constant. The position and velocity of the vessels carrying transmitter and receiver are known from GPS at all times. Hence, time series of these quantities can be exploited in any way thatproves effective in the removal of their induced Dopplers. Completion of this SBIR program will extend our present commercial coastal HF radar technology to allow surface current maps to be produced from vessels underway without the need for sites on apossibly hostile nation's shore. A strictly commercial application is the exciting prospect of using this technology on oceanographic survey cruises. Our instrumentation, like ADCPs, ROVs, CTDs, and other marine observing systems, would be installed onresearch vessels used by universities and companies that perform surveys for the government and the oil industry. Finally, it could satisfy a request we are frequently asked: can SeaSondes be put on cargo ships passing through narrow straits (e.g., theMalacca Straits leading to Singapore, the biggest port in the world) to map currents ahead and around the vessel as it navigates treacherous, heavily trafficked areas?