Augmentation of Low?Cost GPS Receivers via Web Services and Wireless Mobile Devices

Abstract

Low-cost GPS receivers can produce positions almost instantly, however they have a limited use and application due to the impact of random and systematic errors associated with real time autonomous positioning. To achieve higher levels of accuracy and precision, some other form of correction or augmentation information must be applied. There are various real time augmentation alternatives, such as WAAS/LAAS, integrated sensors and systems, receiver based optimal estimation algorithms, and potentially, combined GNSS. To improve the accuracy of low-cost GPS receivers, a feasible option is Differential GPS (DGPS). A popular means for transferring real time DGPS corrections is via the RTCM SC-104 protocol over radio transmission. In recent times, the Internet has been shown to be an efficient and reliable form of data communication. In this paper, the Web services architecture is examined as a viable protocol and communication alternative for disseminating DGPS augmentation information over the Internet. Preliminary results from a simple prototype indicate that Web services offers a practical, efficient and secure method for exchanging CORS network data, and augmenting GPS enabled mobile devices capable of wirelessly reaching the internet. Web services are further shown to provide advantages for disseminating other GPS related data, such as IGS satellite orbit data, carrier- phase data for location-centric augmentation, and a host of other LBS information.