Date: July 30, 2019
Author: Terry Southern, CEO
Back in September 2017, we wrote a Blog on New Zealand Trialling Centimetre Level GNSS. We are excited that the New Zealand government have now announced that they have budgeted nearly $2m to support the development of a regional satellite-based augmentation system (SBAS) to significantly improve GPS accuracy. This blog takes a quick recap of the SBAS technology and why it will be so valuable for New Zealand.
For those who want a more in-depth read (on the history and technical nature) of the Global Navigation Satellite Systems check out our Blog on New Zealand Trialling Centimetre Level GNSS.
In any case, a very brief recap is provided below:
Figure 1: U.S. Global Positioning System (GPS)
(1)
Figure 2: GNSS receiver with GNSS satellites transmitting their information needed for receiver to calculate its position.(2)
Figure 3: Contributing factors to GNSS positional error.(2)
Figure 4: Diagram showing key features of DGNSS.
Much like DGNSS, the Satellite Based Augmented System (SBAS) also makes use of reference stations to provide correction data to the rover. However, rather than using a single reference station, SBAS makes use of several reference stations spread over the entire operational area. By using several reference stations, a map of the atmospheric effects is generated and this allows the system to cover large areas. Along with the atmospheric effects, the reference stations also allow for correction data of satellite orbital error and satellite clock errors to be accounted for. The correction information is then beamed to a geostationary satellite, which in turn broadcasts the correction data back to earth, allowing the rover to make a local correction. Since this correction data is sent over the existing GPS L1 channel, this can be received by existing GNSS receivers without the need for any additional antennas or hardware. This means that the existing single receiver GNSS devices could make use of this correction data with just a firmware update. Systems similar to SBAS have been available in the USA (Wide Area Augmentation System WAAS) and Europe for a number of years and allows for a positional accuracy of 1 - 2 m.
Figure 5: Diagram of SBAS core features.(3)
Like all infrastructure, it takes plenty of time and money to roll out nationwide.
As this technology will ultimately be used for Saftey Critical applications (eg: Aviation), it is understandable that it needs to be thoroughly trailed and tested first.
In 2016 Land Information New Zealand (LINZ) announced that it was collaborating with Geoscience Australia (now called "Positioning Australia") in a two year trial of SBAS. As part of the SBAS test-bed trial, three technologies were assessed:
Figure 6 – Present GPS channels.(2)These trials (between January 2017 and January 2019) are thought to have been highly successful.
Read more at
Australian Flying.
Indeed, implementing this technology will not be a low cost exercise. Land Information New Zealand (LINZ) has set aside $NZ1.992 million in their 2019 Budget while Positioning Australia received $A160.9 million in their 2018-19 Federal Budget. Both will co-operate in delivering a regional satellite-based augmentation system for both countries. The funding will be used by LINZ and Positioning Australia to jointly develop specifications and to undertake initial procurement processes. Once a preferred provider for delivering SBAS has been identified, approval for further funding will be sought to implement a regional SBAS.
“GPS usually provides positioning information accurate to about 5-10 metres. This new system will improve the accuracy to less than a metre, and in some devices to 10 centimetres.”
“This data is fundamental to a range of applications and businesses worldwide. It increases our productivity, secures our safety and propels innovation.”
Matt Amos, LINZ National Geodesist.(4)
In short, SBAS will make positioning data, like GPS, even more accurate than it is now.
Examples of SBAS applications include:
As mentioned above, it does take time to roll out such safety critical technology. Therefore New Zealanders (and Australians) will need to "hurry up and wait" before getting their hands on this new tech.
Investigations and procurement will be carried out this year and next. Tenders will apparently be out in 2021 and hence the technology is only slated to be operational in 2023. Read more here.
At Beta Solutions we will continue to follow SBAS roll out closely as we are excited about the possibilities this new technology will unlock in the product design solutions we can offer our clients.
If you have a problem which could possibly be solved through the use of accurate Global Positioning, feel free to contact us to talk to someone in our knowledgeable team.