CATNET, a permanent GPS network

Julià Talaya, Ernest Bosch

Abstract:	Since permanent GPS stations were identified as a key re-source for the geodetic community, the number of perma-nent GPS networks has grown considerably. During the past few years there has been increasing demand for real-time GPS applications: RTK, GPS meteorology, volcano monitoring, TEC estimation, etc. Therefore, real-time ca-pabilities of the permanent GPS networks will play an important role in the near future. Since 1992, the Institut Cartogràfic de Catalunya (ICC) has deployed a permanent GPS network that covers the area of Catalonia. The network consists of 8 stations, with an aver-age distance of 100 km. between them. The ICC is deploy-ing a satellite communication system to provide the GPS network with real-time capabilities. The system will be based on VSAT (Very Small Aperture Terminal) technol-ogy, and will be divided into three segments: VSAT termi-nals to be installed at the GPS sites, a spatial segment with a capacity of 112 Kbps and a central Hub site located at the ICC’s headquarters. The GPS receivers will send data at 1 Hz to the VSAT terminal, which will transfer it to the central Hub at the ICC. Once the data has been received, it will be processed by the GPS data server, which will store the observations and set the appropriate UDP/IP channels, in order to feed data to the different real-time services to be provided by CATNET. In addition to this, GPS files will be available in order to perform real-time GPS water vapor estimation for meteorology. The various real-time services provided by CATNET will be broadcast via DAB (Digital Audio Broadcasting), the new digital radio standard. DAB has a capacity of 1.7 Mbps, allocating up to 6 high-quality audio programs, and a significant amount of space (at least 150 Kbps) will also be available for data transmission. The real-time data will be transmitted using TDC (Transparent Data Channels), which can be configured from 9.6 up to 115 Kbps. The first test on DAB data transmission was carried out in March, and in July 1999 a test was completed on the broadcasting of RTK information using DAB Transparent Data Channels (TDC).
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	33 - 40
Cite this article:	Talaya, Julià, Bosch, Ernest, "CATNET, a permanent GPS network," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 33-40.
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