Dredging Research Program. Feasibility of a Kinematic Differential GlobalPositioning System

摘要

This report considers the feasibility of using the Global Positioning System(GPS) to obtain three-dimensional positions, at decimeter (or better) accuracies, in real time for hydrographic survey vessels, dredges, and offshore tide gage buoys. The various technical constraints associated with using GPS to obtain high-accuracy positions of a moving platform are discussed. Real-time, decimeter-level kinematic differential GPS positioning can only be obtained if GPS carrier beat phase ambiguities can be resolved on the fly. Resolution of carrier beat phase ambiguities on the fly can only be achieved (if at all) with improved P-code pseudoranging. Dual-frequency receivers will be required. Codeless techniques for tracking the P-code may be almost as useful as code-correlation techniques in providing pseudorange measurements for carrier beat phase ambiguity resolution. Problems in four areas remain to be solved if decimeter-level systems are to be feasible: reducing pseudorange noise, avoiding multipath, overcoming possible adverse effects of selective availability, and overcoming the effects of vessel dynamics.