New Differential and RTK Corrections Service for Mobile Users, Based on the Internet

H. Hada, H. Sunahara, K. Uehara, J. Murai, I. Petrovski, H. Torimoto, S. Kawaguchi

Abstract:	This paper briefly describes and compares services for GPS differential corrections that currently exist in Ja-pan. New public demands that include availability, low cost and high accuracy are highlighted. To meet these new demands, new Differential and RTK corrections services through the Internet has been pro-posed. At the beginning, this service will be used domesti-cally, but it also can serve as a basis for the future world-wide differential corrections service. The proposed service will be used by nearly all types of GPS users in Japan, each of which can choose upon available messages. Practically all domestic car navigation systems are considered as po-tential users of this service. We also expect this service to be broadly used by the surveyors, construction workers, and other GPS users. The main advantage of this service is that it based on the Internet and therefore is open to public by the definition. In addition, our service covers both differential and RTK corrections for both GPS and GLONASS. One can expect the new Differential and RTK Corrections Service to suc-cessfully compete other available in Japan services and be-came a principal one. This work is a part of the WIDE (Widely Integrated Distributed Environment) project, which is supported by many Japanese major companies and universities, and aims the Internet implementation in different parts of everyday life. This paper presents a concept of the Internet Differ-ential and RTK Corrections Service, a description of com-ponents and a technology of implementation. An analysis of advantages and drawbacks of the Internet, not only as a data link, but also as a database for GPS based navigation com-plexes is presented. The paper discusses limitations of the Internet, technical problems of such implementation and different ways to overcome it. Particularly, an impact of a limited capacity and speed of the Internet lines are consid-ered. The paper also presents new protocol, which have been designed in order to support potentially enormous number of clients. The other issue that discussed in the paper is how to choose the best suitable for the user server among the avail-able. The paper introduces the Service Location Protocol, which have been designed for this purpose. The trial sys-tem, which has been tested as the Internet Differential and RTK Corrections Service prototype is described. A rover GPS receiver in this system is connected to the Internet by cellular telephone. A GPS receiver in the Internet Differen-tial and RTK Corrections Service works as a sensor that de-livers an information to the Internet and as a client, which consume the information. The trial system that consists of the seven reference stations and five rovers is described. The rover GPS re-ceiver is connected to Internet by cellular telephone. GPS in this system works as a sensor that delivers an information to Internet and as a client, which consume the information. In conclusion, the results of the system test are presented.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	519 - 528
Cite this article:	Hada, H., Sunahara, H., Uehara, K., Murai, J., Petrovski, I., Torimoto, H., Kawaguchi, S., "New Differential and RTK Corrections Service for Mobile Users, Based on the Internet," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 519-528.
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