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Author: | Li, Xiyin |
Title: | Improving EGNOS Service in Finland Using Internet Radio Technology |
Publication type: | Master's thesis |
Publication year: | 2006 |
Pages: | 66 Language: eng |
Department/School: | Maanmittausosasto |
Main subject: | Geodesia (Maa-6) |
Supervisor: | Vermeer, Martin |
Instructor: | Chen, Ruizhi |
OEVS: | Electronic archive copy is available via Aalto Thesis Database.
Instructions Reading digital theses in the closed network of the Aalto University Harald Herlin Learning CentreIn the closed network of Learning Centre you can read digital and digitized theses not available in the open network. The Learning Centre contact details and opening hours: https://learningcentre.aalto.fi/en/harald-herlin-learning-centre/ You can read theses on the Learning Centre customer computers, which are available on all floors.
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Location: | P1 Ark M80 | Archive |
Keywords: | GPS EGNOS SBAS DGPS Internet radio NTRIP virtual DGPS |
Abstract (eng): | EGNOS is a satellite based augmentation system which provides improved performance to the existing GNSS systems over Europe. In order to access the EGNOS service, the end user needs to access the Signal in Space (SIS) from the corresponding GEO satellites, which contains the augmentation information. This would not he a problem for most aviation applications as an open sky is typically available. However, for land applications especially at high latitudes, it might he difficult to access the GEO satellites directly because of the low elevation angles. An Internet-based solution is presented in this thesis to solve the problem of low availability of the EGNOS SIS. The EGNOS signal is first converted to a virtual DGPS signal in RTCM format. The virtual DGPS signal is then broadcast over the Internet using the Internet radio technology. The generation of the virtual DGPS signal consists of two main components. The first component is to calculate the pseudorange correction for a certain location based on the SBAS corrections. The fast correction, long term correction, ionospheric correction in SBAS messages should be considered, while the tropospheric correction should be computed from the given empirical model. The second component is to encode the DGPS corrections into the RTCM messages. Three types of RTCM messages are implemented, the DGPS correction message MT 1, the reference site message MT 3 and the filling message MT 6. The virtual DGPS data streams are disseminated over the Internet based on the NTRIP (Networked Transport of RTCM via Internet Protocol) protocol. The system consists of four components: the NtripSource for generating the source data stream to be broadcast, the NtripServer for forwarding the source data streams to the NtripCaster, the NtripCaster for broadcasting the data streams over the Internet, and the NtripClient for receiving the data stream from the Internet and forwarding it to the rover receiver for DGPS positioning. The NtripCaster is the core component of the whole system. An NtripCaster software has been developed on the Windows platform. A multipurpose software has also been developed under Windows for serving as NtripServer, NtripClient, and data logging software. Furthermore, NtripClients for PocketPC and SmartPhone have also been developed in this study. Tests for the Internet radio system and for the virtual DGPS system are implemented. A high availability and a low time delay are obtained in the tests for the Internet radio system. The static and driving tests shows that the virtual DGPS system has a similar accuracy as the standalone EGNOS solution. |
ED: | 2006-06-07 |
INSSI record number: 31948
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