Title: EDAS (EGNOS Data Access Service): Differential GPS corrections Performance Test with State-of-the-art Precision Agriculture System
Author(s): J. Vázquez, E. Lacarra, M.A. Sánchez, J. Rioja, J. Bruzual
Published in: Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017)
September 25 - 29, 2017
Oregon Convention Center
Portland, Oregon
Pages: 1988 - 1998
Cite this article: Vázquez, J., Lacarra, E., Sánchez, M.A., Rioja, J., Bruzual, J., "EDAS (EGNOS Data Access Service): Differential GPS corrections Performance Test with State-of-the-art Precision Agriculture System," Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017), Portland, Oregon, September 2017, pp. 1988-1998.
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Abstract: EDAS (EGNOS Data Access Service) is the EGNOS internet broadcast service, which provides free of charge access to the data generated and collected by the EGNOS infrastructure. EDAS gathers all the raw data coming from the GPS, GLONASS and EGNOS GEO satellites collected by all the receivers located at the EGNOS reference stations, which are mainly distributed over Europe and North Africa. Once the data are received and processed, EDAS disseminates them over the Internet in real time and also through an FTP archive. The EDAS services portfolio is the result of various protocols and formats supported, along with several types of information made available to users by each service. This paper investigates the potential use of EDAS Differential GNSS corrections to support precision agriculture applications, by analysing the achieved performance during a dedicated in-field test campaign that has been conducted by ESSP and Topcon Agriculture. EDAS service provision is performed by ESSP, as EGNOS Service 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 the GSA. ESSP also manages the EGNOS Helpdesk, which provides technical support to users by answering to any potential question or by providing clarifications about EGNOS services, thus including EDAS. In 2016, ESSP presented at the ION GNSS+ conference [21] the EDAS DGPS corrections performance achieved by applying EDAS DGPS corrections to the GNSS measurements from public reference GNSS stations (EUREF) at selected European locations in real-time during a 5-week period [21]. That study showed that horizontal accuracies below 1 meter (95th percentile) can be achieved using EDAS DGPS corrections up to a distance of 250 km from the designated EGNOS station and that, within that range, pass-to-pass accuracies (15 minutes, 95%) were expected to remain below 20 cm. However, those pass-to-pass results were considered preliminary since they were based on post-processed static data (according to ISO 12188-1) and needed to be confirmed by in-field tests, i.e. considering the environmental and dynamic conditions of farming operations. This year, ESSP complements the study presented last year by conducting in-field tests aiming at measuring the pass-to-pass accuracy that can be supported by EDAS DGPS corrections in a dynamic and real-life environment. In order to assess and validate the in-field tests, Topcon Agriculture joined ESSP for the activity. Topcon receivers, vehicles and guidance systems were used in order to confirm the suitability of the EDAS DGPS corrections for precision agriculture. Firstly, this paper introduces the EDAS system and its architecture, presenting the main types of data disseminated through its services and the online information available to the users. As part of this introduction, special attention is put on the description of the EDAS Ntrip service. This service has been the main enabler for the performance tests presented in the scope of this paper, since it provides differential corrections to the GPS and GLONASS satellites in RTCM format, taking the EGNOS stations as reference stations. Then, the paper describes the test scenarios and setups at the selected farm in Europe. Two different Topcon guidance systems on board tractors were running simultaneously to assess the EDAS DGPS positioning performance with respect to a reference, which was provided by an RTK-based Topcon solution. In each test, multiple runs with the rover tractor were performed over the reference patterns previously defined in the Topcon guidance systems. This paper presents a detailed analysis of the data recorded during the tests, especially in terms of the key performance indicators of the EDAS DGPS solution with respect to the RTK one. The in-field tests results show that the DGNSS corrections broadcast by EDAS could be a suitable solution for cereal farms (in particular for spraying/spreading of any crop type and tilling and harvesting of cereal), when located within a reasonable distance (below 250 km approximately) to the target EGNOS reference station. It is to be noted that cereal farms represent around 80% of the farms in Southern Europe.