Positioning technology has long played a vital role in navigation for transport. From using compasses, sextants and chronometers, transport operators and users have moved on to using satellites to provide more precise positioning information.

All modes of transport are now using global navigation satellite systems (GNSS), such as the United States Government’s Global Positioning System (GPS)(external link) that is provided free of charge to users.

From sat-nav devices in vehicles, navigation avionics in aircraft and electronic chart tables on ships, to passengers using their smart phones to find out about public transport options, the transport system is now very much reliant on GNSS.

For many potential transport applications, however, GNSS does not provide sufficient accuracy or integrity. It is only reliably accurate to within 5 to 10 metres that, for example, will tell what road a vehicle is on but not what lane the vehicle is in. This is likely to be insufficient for future connected and automated vehicles and for charging for road use by location and time. Nor can unaugmented GNSS be relied on to guide aircraft when landing in bad weather when the clouds are particularly low.

GNSS accuracy and integrity can be improved by what is called a satellite based augmentation system (SBAS). SBAS improves the positioning and timing accuracy and integrity of global satellite navigation systems such as the global positioning system (GPS). SBAS involves the use of a network of ground reference stations to compute corrections for sending GNSS receivers via satellite.

Reliable SBAS coverage is currently available in most parts of the developed world (called, for example, WAAS(external link) in North America and EGNOS(external link) in Europe) but not yet for Australasia. SBAS has applications in other areas apart from transport, including mapping, construction, asset management and precision agriculture. Many GNSS receivers in New Zealand are already capable of using SBAS signals.

New Zealand participation in SBAS test-bed and trial programme

The New Zealand Government has accepted an invitation from Geoscience Australia, on behalf of the Australian Government, to be involved in a trial of current and next-generation SBAS(external link). New Zealand is investing A$2 million in this project with a view to helping see if a business case can be made for the provision of a permanent SBAS service for Australasia. More information about this project is available on the Land Information New Zealand web site(external link).

The SBAS test-bed is being provided by Lockheed Martin, GMV and Inmarsat. The project is running for two years starting in February 2017.

The SBAS test-bed signals will not be able to be used for routine air navigation. For further information on the implications of the test-bed for aviation see the Civil Aviation Authority(external link) web site.