Accuracy Assessment for hand held GPS receivers Supported with WASS/EGNOS Corrections and its implication in Hydrographic survey

Abstract

The Global Positioning System (GPS) has changed the concept of surveying operations from on ground to sky measurements. GPS is designed primarily as a navigation system to satisfy both military and civilian needs for real - time positioning. The differential GPS (DGPS) technique has improved the positioning accuracy. It enables the using of GPS in various applications replacing the time consuming and costly traditional surveying techniques. The differential concept of GPS has been used with at least two receivers to satisfy the required accuracy and to overcome the selective availability (S.A.). After (S.A.) had been turned off, the differential GPS techniques have been improved and became available for the users through Omnistar Network Control Centers (NCC) and Beacons differential corrections. With the implementation of the Wide Area Augmentation System WAAS and the European Geostationary Navigation Overlay Service EGNOS corrections in the recent GPS receivers, it could be used in different engineering applications with no fees and based on the accuracy claimed by the manufactures.