AN ULTRA-HIGH PRECISION POSITIONING AND BATHYMETRIC SURVEYING SYSTEMS

THERE IS A SIGNIFICANT REQUIREMENT FOR BATHYMETRIC INFORMATION WITH ENOUGH PRECISION IN THE VERTICAL AXIS (ELEVATION) TO ASSES LONG TERM PROCESSES SUCH AS SCOUR, SILTING, SUBSIDENCE AND OTHER SUBTLE FLUCTUATIONS I BOTTOM TOPOGRAPHY. PRODUCING HIGHLY ACCURATE BATHYMETRIC SURVEYS IS COSTLY AND ERROR PRONE. MODERN SURVEY SYSTEMS CAN PRODUCE RESULTS ACCURATE TO WITHIN A FEW DECIMETERS IN THE HORIZONTAL PLANE, BUT IN ALMOST ALL CASES DEPTHS ARE REFERENCED FROM THE WATER SURFACE, GIVING RISE TO SIGNIFICANT ERRORS DUE TO EFFECTS FROM WIND, TIDES, CURRENTS AND COMPLEX HYDROGRAPHY. SYSTEMS WHICH CAN ACHIEVE THE REQUIRED VERTICAL RESOLUTION RELY UPON TRACKING THEODOLITES OR LASER LEVELING SYSTEMS AND REQUIRE SIGNIFICANT CALIBRATION AND SHORESIDE SUPPORT. THE USE OF KINEMATIC SURVEYING TECHNIQUES ROUTINELY PRODUCES ACCURACIES OF A FEW CENTIMETERS ON LAND. KINEMATIC SURVEYING IS HIGHLY PROBLEMATIC ON A CONTINUOUSLY MOVING PLATFORM, HOWEVER. WE PROPOSE AN APPROACH WHICH COMBINES KINEMATIC SURVEYING TECHNIQUES WITH A LOW COST INTERTIAL NAVIGATION PACKAGE CALIBRATED BY A GPS ATTITUDE DETERMINATION SYSTEM. THE PROPOSED SYSTEM IS EXPECTED TO BE HIGHLY TOLERANT OF TEMPORARY GPS OUTAGES AND TO ALSO SUPPLY PRECISE VESSEL ATTITUDE INFORMATION FOR USE IN CORRECTING FOR THE DEPTH SOUNDING GEOMETRIC ERROS. A FULLY INTEGRATED PACKAGE INCLUDING POSITIONING, MULTIBEAM ECHO SOUNDING AND BOTTOM CLASSIFICATION, AND DATA LOGGING WILL BE PRODUCED AS PART OF PHASE II.