Real-Time Centimeter-Accuracy GPS Based Location Revisiting in Open Water

In order to research and monitor the ecology or environmental changes of a water area, efforts are involved in the areas of data collection, management, biological communities and habitat, bottom sediment, and air and chemical depositions. To exactly research the ecosystem of a certain water area, the research crew has to return to the same area to collect data. Especially, in an open water area, it is difficult to find again the location that you have encountered before. Therefore, to bring a research ship back to the same location or area periodically, the Differential Global Positioning System (DGPS) is employed, and the GPS phase measurements are used to achieve centimeter accuracy in positioning. As a result, researchers have more reliable options to guide them to the desired research area. However, integer ambiguities in the phase measurements have to be resolved to achieve the desired high accuracy positioning. In this project, an innovative algorithm for resolving the integer ambiguities on the fly is proposed to effect highly accurate estimates of the research ship's position in real time. Based on the algorithm, a software package is developed and will be embedded in a real-time navigation system.