Using network RTK corrections and low-cost GPS receiver for precise mass market positioning and navigation applications

With the advancement in GPS receiver hardware and data processing technologies in recent years, more and more low-cost GPS receivers could output instant high quality carrier phase measurements to provide navigation solutions with an accuracy of a few meters. It is anticipated that improved GPS positioning performance will open doors for many new ITSS and Location-based Services (LBS) applications. This is the reason why the exploitation of the raw carrier phase measurements generated with low-cost receivers has attracted attention of researchers and manufacturers around the world. The University of Nottingham, The Chinese Academy of Surveying and Mapping, and Wuhan University in China have teamed up in recent years to research and develop new positioning and navigation algorithms. These algorithms are used to decode real-time carrier phase measurements from low-cost single frequency GPS receivers, collect instant network RTK corrections via GPRS/3G connections, resolve integer ambiguities and output real-time positioning solutions. A prototype system has been devised and extensively tested using the advanced facilities at the University of Nottingham and in China. It has been found that better than decimeter real-time on-the-fly positioning precision could be achieved. In this paper, the design and structure of this prototype system is introduced first. It is followed by a brief description of the newly developed ambiguity search and resolution technologies. A series of tests under a controlled environment have been conducted and the results are analyzed through comparison with “ground truth” trajectories. Preliminary conclusions are drawn in the paper and discussions are made to further improve the performance of this system.