This thesis examines the current implementations for the distribution of real-time GNSS data over IP networks such as the public Internet, focusing on two essential components of the system, data format and transport protocol. The provision of a suitable data format will allow users to take full advantage of the real-time GNSS data distribution system. Types of GNSS supported, message sizes, data rates, data precision levels, hardware and software support and possible future developments are investigated. An analysis is carried out on commonly known GNSS data formats, highlighting the most suitable standard for each evaluation criterion. A similar investigation is carried out on the transport protocols. An analysis is conducted on various design aspects of NTRIP and RT-IGS protocols, covering factors such as data latency, integrity, firewalls and proxy server compatibility and scalability. The analysis also covers the design aspects of the new draft Version 2 of NTRIP. The latter parts of this thesis report on the experiment results aimed at providing assessment of the current level of implementation of NTRIP. Data latency and integrity using NTRIP over the Internet are examined. Their impacts on users applications as the quality of real-time kinematic positioning is assessed. The results show that the performance of the system satisfies the rigorous requirement of the end-user application. The draft version of the new NTRIP indicates that UDP will be also supported. A similar investigation is carried out, providing the first experiment results on the new option. Tests using similar metrics, data latency and integrity, were carried out to verify the inherent differences between TCP and UDP. It was ascertained that, in most cases, UDP does offer improvement in terms of reduced latency over TCP. However this improvement is not significant enough to affect the performance of users applications tested. Compatibility tests were also carried out and the test results show that the new option experiences some compatibility issues with firewalls and wireless networks.
| Identifer | oai:union.ndltd.org:ADTP/230057 |
| Date | January 2008 |
| Creators | Yan, Thomas Surya Sanjaya, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW |
| Publisher | Publisher:University of New South Wales. Surveying & Spatial Information Systems |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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