High-Precision Real-Time Differential Positioning Using Low-Cost GPS Receivers

Recent survey results of the navigation market indicate a growing need for precise realtime positioning on land, on sea, in air and space (e.g. navigation of dredging vessels, automated aircraft landing, positioning of airborne sensors). Post-mission analyses of observations using the Global Positioning System have already shown the potential of the GPS system to deliver centimeter accuracies over baselines of several hundreds of kilometers. It is therefore a challenge to develop also a GPS navigation system with such a high accuracy level.The paper introduces a system based on six-channel low-cost C/A code receivers reaching accuracies in the decimeter range in real-time and in the centimeter range for post-mission.The receivers are controlled by separate processors which are communicating via a radio link in the UHF band. The controllers are IBM compatible and are communicating with the receivers via serial interfaces. The hard- and software components and the underlying algorithms are described in detail. The system allows update rates of 1 Hz and the delay for the position fix is less than two seconds.In order to prove the accuracy and the performance of the system several experiments were performed using the system in different environments. Results of these tests are presented.