EDAS (EGNOS Data Access Service) for Added Value Applications

J. Vázquez, E. Lacarra, M.A. Sánchez

Abstract:	EDAS (EGNOS Data Access Service) is the ground-based access (through the Internet) to EGNOS data in real-time and also through a historical archive, which collects all the data generated by the EGNOS infrastructure. In consequence, EDAS gathers all the raw data coming from the GPS, GLONASS and EGNOS GEO satellites collected by all the receivers located at the EGNOS stations, which are mainly distributed over Europe and North Africa. Once the data is received, EDAS disseminates this GNSS data in real-time to EDAS users and/or Service providers that distribute the data locally or to specific set of applications. In consequence, EDAS allows users to "plug in" to the EGNOS system by providing access to GPS/GLONASS satellite navigation and observation data, along with the EGNOS messages as received by EGNOS ground stations. EDAS service provision is performed by ESSP, as EGNOS Services Provider, under contract with the European GNSS Agency (GSA), the EGNOS program manager. The European Commission (EC) is the owner of EGNOS system (including EDAS) and has delegated the exploitation of EGNOS to GSA. ESSP also manages the EGNOS Helpdesk, which provides technical support to users answering any potential question or clarification about EDAS, along with the registration of new EDAS users. The continuous provision of EDAS Services started in 2009. On April 2013, a new set of added value services were declared available, enabling a wider range of additional applications. Currently, the Services provided by EDAS are the following: • Main Data Streams: EGNOS data is provided through Internet on real-time in ASN.1 format (Service Level 0) and RTCM 3.1 format (Service Level 2), covering: o Raw GPS, GLONASS and EGNOS GEO observations and navigation data received by all EGNOS Stations o EGNOS augmentation messages. • Data Filtering: Filtering capabilities to allow receiving EGNOS data from only certain subsets of RIMS stations when connecting to EDAS Service Level 0 and 2. • SISNET Service: EGNOS messages provided in real time using the SISNeT protocol defined by ESA. • FTP Service: Historical EGNOS data available through an FTP site, including: o EDAS SL0, SL2 raw data. o GPS/GLONASS navigation and observations (RINEX format) o EGNOS messages (ems + RINEX-B formats) o IONEX data files ? Ntrip service: RIMS raw measurements are provided in real time using the Ntrip protocol. Apart from enhancing the precision of position data derived from satellite-based positioning systems, EDAS supports a variety of commercial applications and research programs. Firstly, the paper will introduce the EDAS system and its architecture, informing about the main types of information that are available through its real-time and off-line services. Secondly, the paper will shortly describe each EDAS service (main streams, data filtering, Ntrip, SISNET and FTP), showing the types of information provided, the applicable standards and their main features. It will present the online information available in relation to this Service: the EDAS Service Definition Document (EDAS SDD) that describes its characteristics, conditions of access and committed performances (in terms of availability and latency), the EGNOS User Support website where a user can apply for the registration of these Services, the EGNOS Monthly Performance report, publicly available, which includes the EDAS performances of the reported period and the EGNOS Helpdesk, which is main point of contact available to EGNOS users. Recent EDAS performances in terms of availability and latency will be shown, presenting trending evolution versus time and statistics. Different techniques that could be applied to improve GPS standalone positioning accuracy will be explained, such as the application of the EGNOS messages using EDAS SISNET, the computation of Real-Time Kinematic position or Differential GNSS navigation solution through the EDAS Ntrip Service. In addition, accuracy results for the aforementioned positioning techniques based on EDAS data and oriented to specific application domains will be presented. As an example, and for the case of agriculture, an estimation of the achievable pass-to-pass precision will be provided. Other potential techniques and possible areas of application for the EDAS Servicers that are under investigation in other domains, such as maritime, will be introduced. For this domain, EDAS could contribute to a positive business case in different use cases thanks to the transmission of GNSS data from EDAS data through the standards navigation information channels widely spread in the maritime sector. In conclusion, different positioning techniques will be presented in order to invite the GNSS community to use the already available set of EDAS Services. This message will be reinforced showing the available results, experience and performances.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	1 - 13
Cite this article:	Vázquez, J., Lacarra, E., Sánchez, M.A., "EDAS (EGNOS Data Access Service) for Added Value Applications," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 1-13.
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