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How TerraStar is meeting the growing demand for correction services

Interview with Sara Masterson, Director, Positioning Services, Hexagon’s Autonomy & Positioning division, Hexagon | NovAtel


Sarah Masterson, Hexagon | NovAtel

The accuracy of GNSS receivers continues to increase thanks to new satellites and signals, improved antennas, etc. How is that changing the role of correction services?

For sure, the accuracy of GNSS receivers and antennas is improving. However, most applications still require a higher level of accuracy than what is available from an uncorrected position even with the positioning improvements brought by new constellations and signals. GNSS corrections are still required to enable, say, lane-level accuracy, or sidewalk-block accuracy for autonomous driving or mobile phone applications and for off-road autonomy applications such as construction, mining, agriculture — these all still require centimeter-level accuracy that is enabled through GNSS correction services.

Corrections also help by improving the availability and reliability of a solution. In the future, corrections will play a key role in adding integrity to enable functionally safe solutions that are required for new applications, such as autonomous driving.

There are many options for corrections — local, regional and global, ground-based and satellite-based, public and private, etc. Which of them are generally best for which applications and conditions?

That depends very much on the user and the application. There are many new correction services in the market. Some are free, some are commercial services. Even now we see in agriculture that WAAS is sufficient for some broadacre-type applications. So, we will continue to see a range of applications, some of which will be satisfied with the level of performance from a free service and others that will be looking for the better performance and service level guarantees that come with commercial services.

If something is not working when you are using a free service, there’s no one to call. With commercial services, you get responsive customer support and you pay for higher levels of performance and service availability. In many applications, especially those that involve autonomy or safety applications, you cannot afford to have downtime, or your machine just stops working, which costs money. So, many applications are still going to be needing the performance and service level guarantee that commercial services offer.

How does TerraStar fit into this range of options? What industries and applications are you targeting?

TerraStar has a range of services that enable us to target many industries and applications. Agriculture, of course, is one of the key applications for our services and we have customers using TerraStar for mobile mapping, UAVs and new autonomy-based applications. We are also involved with some interesting Hexagon joint projects that use TerraStar corrections for mine train automation and surveying and construction.

Our entry-level TerraStar-L service is still better in performance to many of the free services or to an SBAS-type service in terms of accuracy, but it is available globally, including regions where you don’t have other options. It also provides better pass-to-pass and year-over-year repeatability, as well as very quick reconvergence time if there are any issues with GNSS outages.

Our flagship offering is the TerraStar-C PRO service. That’s where we just introduced the “RTK from The Sky” technology, bringing the performance down to converging to two and a half centimeters in three minutes. That, too, is available globally which makes it a real game changer for customers in many different applications, because they can start to look at that service as an alternative to RTK and without the added connectivity logistics that an RTK solution brings.

Our RTK assist solutions are good augmentation solutions for customers who still primarily need RTK but experience some RTK correction outages – RTK ASSIST bridges through those outages. So, we have a wide range of service offerings in the portfolio that can address the positioning needs of many applications.

A Massey Ferguson tractor guided by a NovAtel GNSS OEM receiver. (Photo: Hexagon | NovAtel)

Photo: Hexagon | NovAtel

Will the reasons for having a base and rover setup decrease sharply?

Use of base and rover setups is already decreasing and being replaced by both PPP and network RTK solutions. There are applications where RTK still makes sense, such as those that have very tight vertical requirements and many survey applications. Another Hexagon division, Hexagon’s Geosystems division, incorporates TerraStar correction data into their new SmartNet Global offering as a seamless service that provides both SmartNet RTK plus TerraStar for either bridging outages or independent PPP operation, depending on the project’s location and whether they’re within range of SmartNet coverage.

There will be many applications that continue to benefit from a combination of the two technologies. However, as the PPP services, like TerraStar, continue to improve by reducing convergence time and providing highly reliable solutions, users in those applications can be confident that the standalone PPP solutions meet their performance needs and bring many additional benefits such as consistent, global coverage and performance.

Is TerraStar completely receiver agnostic?

TerraStar is currently only compatible with NovAtel’s GNSS hardware. Going forward, through the work that I referenced with autonomous driving and mass-market applications, we will be providing TerraStar services in industry-standard formats, depending on the inter-operability requirements coming from those applications. We expect that there will be demand for dual sourcing of corrections and interoperability between chipsets that are used in vehicles, for example. For those applications, we will be developing TerraStar services that are compatible with hardware from other GNSS manufacturers.

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