Satellite signal research to boost positioning

Research using a satellite-based augmentation system will lead to more accurate positioning services in Australasia.

The Australia and New Zealand CRC for Spatial Information (CRCSI) will lead an industry program that evaluates applications on a recently announced satellite-based augmentation system (SBAS) testbed. CRCSI partners Geoscience Australia and Land Information New Zealand (LINZ), together with three companies — GMV, Inmarsat and Lockheed Martin, will implement the SBAS testbed through a two-year project to evaluate three positioning signals for improved accuracy and integrity over Australia and New Zealand.

“The SBAS testbed will trial a range of SBAS signals for the first time in Australia, one of which has never been tested before. The SBAS signals provide an opportunity for many users to more readily access higher accuracy satellite positioning over Australia and New Zealand,” said Dr Peter Woodgate, CEO of the CRCSI.

“The SBAS testbed is Australia’s first exploratory step to joining countries such as the United States, Europe, China, Russia, India and Japan, which are already using the technology on a daily basis,” added Gary Johnston, head of Geoscience Australia’s geodesy and seismic monitoring section.

“This technology hasn’t been widely tested in Australia before; however, GMV, Inmarsat and Lockheed Martin have experience implementing it around the world,” Johnston added.

“The testing of SBAS technology in Australia offers a number of potential safety, productivity, efficiency and environmental benefits to many local industries, including transport, agriculture, construction and resources.

“Research has shown that the widespread adoption of improved positioning technology has the potential to generate upwards of $73 billion of value to Australia by 2030,” said Johnston.

In January 2017, the Australian Government announced $12 million in funding for the trial of SBAS technology.

Johnston said Geoscience Australia will be collaborating closely with GMV, Inmarsat and Lockheed Martin on the technical components of the testbed.

“We’ll be testing two new satellite positioning technologies — next-generation SBAS and Precise Point Positioning — which provide positioning accuracies of several decimetres and five centimetres respectively.”

Australia currently relies on the Global Navigation Satellite Systems (GNSS) of other countries, including the United States’ GPS. These international systems typically give Australians positioning accuracy of five to 10 metres.

The three signals to be tested are:

• The current offering provided in Europe and the US (L1 Legacy signal).
• A new dual-frequency signal to be tested for the first time in both Australia and New Zealand (L5 Dual-Frequency and Multi-Constellation Signal).
• High-precision, Precise Point Positioning (PPP) navigation corrections where decimetre-level accuracies at user level are expected.

In simple terms, the SBAS satellite provides a cost-effective way to improve GPS signals from around 5 metres in accuracy to less than 1 metre.

In March, Geoscience Australia and the CRCSI will call for organisations from a number of industries including agriculture, aviation, construction, mining, maritime, rail, road, spatial and utilities to participate in the testbed.

SBAS is expected to improve air navigation, smartphone-based services, asset management and precision agriculture, and is expected to be needed for the deployment of connected and autonomous vehicles.

The New Zealand and Australian Governments will be partners in the two-year SBAS trial.

“Australian and New Zealand industry will be able to assess new and innovative positioning applications and build the case for further investment,” said the CRCSI’s Dr Woodgate.

“This is a world-leading trial that will allow us to investigate how New Zealand might benefit from the added precision SBAS adds to current and future global navigation satellite systems such as the widely used Global Positioning System (GPS),” said New Zealand’s Transport Minister, Simon Bridges.

“Essentially, SBAS is expected to help ready us for technologies that need more precise and reliable positioning data.

“While current GPS locations are accurate to within 5–10 metres, the SBAS testbed could improve positioning to within as little as 10 centimetres,” the minister added. “This means that a vehicle will recognise the road it is travelling on, but also which lane it is in and its distance from surrounding objects.

“The testbed and trials will be the first in the world to utilise next-generation SBAS technology, putting Australasia ahead of other parts of the world, and showing again why New Zealand is an ideal place to test new technologies.”

The New Zealand Government will contribute $2 million towards the testbed and trial program.

The SBAS testbed will contribute to the initial work program of the Australia–New Zealand Science, Research and Innovation Cooperation Agreement signed in Queenstown, New Zealand, on 17 February.

Industry involvement

The SBAS research project will see Inmarsat using a transponder aboard its L-band Asia Pacific Region satellite, Inmarsat-4 F1 (I-4 F1), to provide the space component of the SBAS Testbed.

GNSS signals are critical tools for industries requiring exact precision and high confidence. For the first time anywhere in the world, this project will demonstrate how the use of signals from multiple GNSS, ie, GPS and Galileo, and SBAS signals broadcast on dual frequencies (GPS L1 and L5), can achieve enhanced navigation performance in terms of user positioning integrity and accuracy.

The navigation payload on Inmarsat’s I-4 F1 satellite is a dual-channel bent-pipe transponder, which provides mobile users with two SBAS navigation signals at both GPS L1 and L5 frequencies. The I-4 F1 satellite was the first in the world to be launched carrying a transponder capable of broadcasting SBAS signals at both GPS L1 and L5 frequencies.

“Being part of this innovative research project is testament to our important heritage on satellite navigation matters,” said Claudio Soddu, Inmarsat VP for Navigation and Special Projects.

“A second-generation SBAS testbed is a natural continuation of the concept of augmenting satellite navigation systems with a separate satellite data and ranging channel that we helped pioneer.

“Having previously been involved in testbeds and operational systems in other regions of the world, this collaboration showcases our capabilities in the Asia–Pacific region and potentially opens the door to further research and development projects in the future.”

“Many industries rely on GNSS signals for accurate, safe navigation. Users must be confident in the position solutions calculated by GNSS receivers,” said Lockheed Martin Australia and New Zealand Chief Executive Vince Di Pietro.

“The term ‘integrity’ defines the confidence in the position solutions provided by GNSS. Industries where safety-of-life navigation is crucial want assured GNSS integrity.”

Ultimately, the second-generation SBAS testbed will broaden understanding of how this technology can benefit safety, productivity, efficiency and innovation in Australia’s industrial and research sectors.

“We are excited to have an opportunity to work with Geoscience Australia and Australian industry to demonstrate the best possible GNSS performance and proud that Australia will be leading the way to enhance space-based navigation and industry safety,” added Di Pietro.

Basic GNSS signals are accurate enough for many civil positioning, navigation and timing users. However, these signals require augmentation to meet higher safety-of-life navigation requirements. The second-generation SBAS will mitigate that issue.

Once the SBAS testbed is operational, basic GNSS signals will be monitored by widely distributed reference stations operated by Geoscience Australia. An SBAS testbed master station, installed by GMV, of Spain, will collect that reference station data, compute corrections and integrity bounds for each GNSS satellite signal, and generate augmentation messages.

“A Lockheed Martin uplink antenna at Uralla, New South Wales, will send these augmentation messages to an SBAS payload hosted aboard a geostationary Earth orbit satellite, owned by Inmarsat,” said Rod Drury, director, International Strategy and Business Development for Lockheed Martin Space Systems Company.

“This satellite rebroadcasts the augmentation messages containing corrections and integrity data to the end users. The whole process takes less than six seconds.”

By augmenting signals from multiple GNSS constellations — both Galileo and GPS — second-generation SBAS is not dependent on just one GNSS. It will also use signals on two frequencies — the L1 and L5 GPS signals, and their companion E1 and E5a Galileo signals — to provide integrity data and enhanced accuracy for industries that need it the most.

Lockheed Martin will provide systems integration expertise in addition to the Uralla radiofrequency uplink. GMV-Spain will provide its ‘magicGNSS’ processors.

Lockheed Martin has significant experience with space-based navigation systems. The company developed and produced 20 GPS IIR and IIR-M satellites. It also maintains the GPS Architecture Evolution Plan ground control system, which operates the entire 31-satellite constellation.

Images courtesy Lockheed Martin and Harris Corporation.

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