TRIGNET, South Africa’s GNSS base station network: past, present and future


GNSS and Geodesy

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Patrick John Vorster, Chief Directorate: National Geospatial Information, South Africa,
Stephan Koch, ZA, Chief Directorate: National Geospatial Information, South Africa,


The Chief Directorate: National Geo-Spatial Information (NGI) is mandated, in terms of the Land Survey Act (Act 8 of 1997), to establish and maintain a national control survey system for South Africa. TrigNet, South Africa’s network of Global Navigational Satellite Systems (GNSS) Base Stations, was established in 1999 and serves as an extension to this system.

TrigNet’s service commenced in 1999 with the provision of Global Positioning System (GPS) data, for post processing purposes, in Receiver Independent Exchange format (RINEX). In 2006 a real-time service, in Radio Technical Commission for Maritime Services (RTCM) format, was introduced where GPS corrections were made available from a single base station. In 2007 the real-time service was extended to include real-time networked solutions for the Cape, Gauteng and Kwazulu-Natal metropolitan areas and GLONASS data was recorded and distributed for the first time. The TrigNet network currently consists of 67 base stations, which have a maximum inter-station spacing distance of 300km.

The data from these base stations is streamed, via dedicated leased lines, to the NGI office in Cape Town where it is processed and made available, free of charge, to national and international users. Future plans for TrigNet are to increase the number of base stations, reduce their maximum inter-station spacing distance, provide an on-line post processing service and incorporate future GNSS systems as and when they become operational. The co-operation that exists between the NGI and national and international organisations/agencies, regarding TrigNet, is to be maintained and enhanced.

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