The EGNOS Service to Provide Ground Based Access to EGNOS – EDAS Beta Test Findings

R. Blasi, G.G. Calini, R. Cardoso-Herce, D. De Greef, J.R. Lopez-Perez, F.J. Jimenez-Roncero, A. Gavin-Alarcon, M. Pesce

Abstract:	This paper introduces EDAS, the EGNOS Data Access Service, what it is and what it does aim at. On the basis of the experience gained during the beta test phase, the paper will introduce the main conclusions obtained, the main applications currently envisaged and will provide insights into the way forward. EDAS allows you to plug into EGNOS to receive the data collected, generated and delivered by Europe's first SBAS satellite navigation system. EDAS therefore provides the opportunity to deliver EGNOS data to users who cannot always view the EGNOS satellites (such as in urban canyons) or to support a variety of other value added services, applications and research programs. Satellite Based Augmentation Systems (SBAS) like, for instance EGNOS and WAAS, improve the accuracy, integrity and availability of GPS. Roughly speaking, these systems consist of a network of monitoring stations that collect GPS measurements. A dedicated facility processes this information to compute the augmentation information, which is nominally sent to final users through a Signal In Space (SIS) broadcast by means of geostationary satellites. In any case, the GPS data collected in the stations is only available internally within the SBAS subsystems. In 2006, the European Commission through the GJU (now superseded by GNSS Supervisory Authority, the GSA) commissioned the EDAS system. EDAS allows any authorised entity to plug into EGNOS to receive the internal data collected, generated and delivered by EGNOS for free. Although the idea of providing GNSS data streams in real time is far from being new, EDAS has some key differentiators, the most important one is probably the service reliability planned for the post-beta test phase. Other benefits that EDAS brings are the high data rate (1Hz), the dissemination of the EGNOS message broadcast by each GEO satellite and the provision of GLONASS raw measurements. Additionally EDAS provides the raw data of the 34 Ranging and Integrity Monitoring Stations (RIMS) and Navigation Land Earth Stations (NLES). EDAS provides two different service levels, which basically differ in the data formats they provide, namely RTCM and ASN.1. EDAS is not an end-user product. The data streams can be used by Service Providers to generate added value to the final customers by improving the availability and accuracy of the positioning. For instance, one may think of a Service Provider that takes the EGNOS message from EDAS and disseminates it to its customers through the Internet or GPRS. In order to further investigate into EDAS added value, GSA launched in April 2009 a free and open beta test phase with Aena as contractor for the EDAS data provision and for engineering activities related to users´ connectivity, users´ feedback gathering and EDAS Helpdesk service. EDAS users got support from the helpdesk to answer any question related to the system (connection, data formats, etc). Since April 2010 ESSP1 is operating EDAS within their EGNOS operations on behalf of the European Commission. Insights of the beta test phase have been gathered and are currently being analysed. The by now more than 50 users are accessing EDAS, composed of companies, SME´s, research institutions as well as universities across Europe. It has been shown that EDAS is providing added value and an interest in EDAS has been identified, especially in some industry sectors, notably Dangerous Goods transportation, Road (RUC, ADAS), Inland Navigation and potentially LBS.2 Hereby, availability is a relevant feature, directly related to the service reliability and to the means of distribution of the data: the signal is perceived as always available. Currently the service model and way forward for the post beta test phase is being shaped. This includes, among other things, a thorough analysis of the suggestions regarding the functionality of EDAS, collected during the beta test phase. The implementation of some of them will further increase the value of the system and its market and public benefit potential. EDAS may facilitate the EGNOS evolutions activities as well as a significant number of R&D activities. In the frame of the 7th Framework Programme numerous research projects are or are planning to take benefit of EDAS to achieve their objectives. Participants in the upcoming FP7 Third Call are invited to consider the use of EDAS in their projects.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1994 - 2001
Cite this article:	Blasi, R., Calini, G.G., Cardoso-Herce, R., De Greef, D., Lopez-Perez, J.R., Jimenez-Roncero, F.J., Gavin-Alarcon, A., Pesce, M., "The EGNOS Service to Provide Ground Based Access to EGNOS – EDAS Beta Test Findings," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 1994-2001.
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