SouthPAN SBAS GPS Testing

What is SouthPAN

SouthPAN is a joint initiative of the Australian and New Zealand governments that aims to provide a Satellite Based Augmentation System (SBAS) to Australia and New Zealand.

A SBAS is a network of local ground and satellite systems that work to boost the accuracy of GPS and GNSS Data.

A SBAS uses a network of stationary land-based GNSS monitors to calculate positional errors when comparing these stationary monitors’ measured locations to their documented positions.

Any differences between the measured location and the documented locations are determined to be an error. Corrections for these errors are then sent to the satellites and are broadcast through the region where the SBAS is located. This leads to much more accurate positioning information.

Unaided GNSS is typically accurate to ~5m. In ideal conditions, SouthPAN can achieve sub-3m accuracy on their L1 SBAS Open Service. 

Why did these governments implement SouthPAN?

The implementation of SouthPAN will result in widespread benefits across many sectors, including agriculture, construction, mining, and other industries. SouthPAN will also support aviation and road transport sectors.

In an economic benefits report conducted by EY, SouthPAN could provide more than $6 billion in economic benefits over the next 30 years. 

SouthPAN and Digital Matter

We have conducted some preliminary tests with our devices using SouthPAN GPS SBAS to improve our positional accuracy. 

Takeaways:

• In open sky, connection with SouthPAN resulted in excellent positional accuracy. The average was ~1.3m and was measured as accurately as 1.003m. Without SouthPAN satellites, we measured between 2-3m accuracy.
• Unfortunately, even with the device in open sky, it took more than 2 minutes for the GNSS receiver to connect to SouthPAN. Time to first fix without SouthPAN aiding is consistently ~30s.
• The increased “on time” required to connect to the SouthPAN satellite will result in the device using a lot more power and is likely not suitable for our battery-powered devices.
• Further, when the device wasn’t in ideal “open sky” conditions (e.g. within a car), the connection to the satellite was extremely unreliable. In addition, the accuracy advantage was outweighed by the required time to find the satellite.
• This testing implies that if the device was further blocked from the satellite (e.g. hidden under a trailer), the connection would be tenuous and the accuracy advantage negligible. 
  
  

Conclusion:

SouthPAN works well for devices that do not have power restrictions and are able to have a GNSS antenna with a clear and open view of the sky.

In summary, SouthPAN shows promise, but due to the increased power it demands from our battery-powered devices, it is currently unfit for Digital Matters purposes.

Digital Matter devices operate in a variety of real-world environments and are often not in ideal “open sky” positioning. For example, devices are often inside vehicles or mounted under trailers. In these circumstances, it appears SouthPAN will provide little to no benefit, and with the increased power demands, may even be detrimental.

The Australian and New Zealand governments plan on increasing the number of SouthPAN satellites in orbit over the next few years. This will likely improve time-to-connect and increase accuracy. We will continue to evaluate SouthPAN as this technology matures and re-evaluate its promise as more and more satellites join the constellation.