Jacinta Bowler
Australia’s satellite positioning system is becoming more accurate.
Last year the Australian and New Zealand government launched an early version of the Southern Positioning Augmentation Network (SouthPAN), and they’ve just announced the construction of SouthPAN’s first dedicated Australian satellite dish.
SouthPAN is a little-known global navigation satellite augmentation system – the first of its kind in the Southern Hemisphere. Although it’s not actually a type of GPS or global navigation satellite system (GNSS), it’s still worth understanding how it works.
Lockheed Martin has been given a $1.18 billion dollar contract to establish the system.
What is SouthPAN?
The network is group of towers, satellites, receivers, and computers that can make GPS and other types of global navigation systems (yes, not just GPS) more accurate.
The team suggest that this could increase accuracy from about 5 or 10 metres to just 10 centimetres.
You might think that your GPS does a pretty good job of getting you from A to B, but there are some inaccuracies that can slip through
“There are a couple of sources of error,” says Flinders University’s Professor Samuel Drake.
“Firstly, you don’t know exactly where the satellite is. The second is as the signal passes through the atmosphere it is going to be distorted a little bit.”
The towers in SouthPAN know exactly their point of measurement, and so when they receive a GPS or other satellite signal, they can work out how far off the satellite is and correct for it.
This new correction can be issued either via the internet or satellite to tractors, marine systems, planes, or cars – allowing basically anything that uses GPS to also have access to this more accurate positioning data.
This is called a Satellite-Based Augmentation System, and there’s plenty across the Northern Hemisphere, but until SouthPAN, there was none based directly in Australia.
Why is this needed?
Although a small amount of error in Google Maps or your favourite running app isn’t too big of a deal, some systems need to be much more precise.
This is particularly important where the internet isn’t available to give back up location positioning.
Aviation and marine systems will both be important users of systems like SouthPAN once it becomes ‘safety-of-life certified’ (expected in 2028) but one of the most surprising users of the technology is farmers.
“When farmers want to do crop spraying, they really want centimetre accuracy because spray is extremely expensive,” says Drake.
“Now they’re going to fully automated tractors, or even if the driver’s there, they’re not relying on the driver to steer, they’re relying on the satellites.”
British company Inmarsat sends these correction signals to farmers already, allowing them this precision accuracy.
However, in April one of the satellites went offline for 12 hours, which severely disrupted farmers using these high-tech tractors.
Although farmers might hope that the introduction and further establishment of SouthPAN might fix some of these problems, this might not be the case.
A month after the outage, Inmarsat and the Australian and New Zealand government came to a US$122 million deal to use future Inmarsat satellites to transmit the SouthPAN correction signal.