Have you met HAS?

The Galileo High Accuracy Service (HAS) completes its first year in operations after its Initial Service Declaration in January 2023, providing good and stable performances since then. 

But what is the HAS?

Essentially, the Galileo HAS brings precise point positioning (PPP) options to capable receivers. More specifically, the service provides PPP corrections through the Galileo signal (E6-B) and by terrestrial means (internet) enabling decimetre level accurate user positioning. 

“Galileo is the first GNSS constellation capable of providing a high accuracy service globally, 24/7 operated with committed performance and for free ” explains EUSPA Executive Director Rodrigo da Costa. “This is unique in that, typically, high accuracy services are either regional, provided for a fee or without a performance commitment.

In doing so, the HAS offers real-time improved user positioning performance down to a decimetre level (in normal conditions, when processed by user PPP algorithm). 

Galileo HAS offers several key differentiators

While other commercially available augmentation services also provide PPP corrections, the Galileo HAS comes with several key differentiators. First and foremost, the service is free of charge, with the signal being freely available over the internet via the Galileo (E6-B) signal. 

This means that if one or more Galileo satellites are in view and the user has a suitable receiver, the signals can be obtained without requiring a further license or a special signal receive.  

Therefore, the corrections are transmitted from the Galileo satellite and not a geostationary communication satellite, it is much easier to receive the corrections in areas like urban canyons. 

It should also be noted that, in addition to Galileo corrections, the Galileo HAS transmits GPS related corrections.

Convergence time and accuracy 

The Galileo HAS Full Service will provide two service levels:

• Service Level 1 (SL1):  With global coverage availability, SL1 provides high accuracy corrections (orbits, clocks) and biases (code, phase) for Galileo E1/E5b/E5a/E6 and E5AltBOC and GPS L1/L5/L2C signals. This SL1 is already enabled by the HAS Initial service (with slightly reduced scope) 
• Service Level 2 (SL2): with regional coverage availability over the European Coverage Area (ECA), SL2 will provide SL1 corrections plus atmospheric (at least ionospheric) corrections and potential additional biases as part of the HAS Full service

While SL1 will have a typical convergence time of less than 300 seconds, SL2’s convergence time will be lower than 100 seconds. 

The user positioning accuracy for both service levels, once the full service is operational, is stated as less than 20cm horizontally and less than 40cm vertically (95% confidence level), whereas the current HAS Initial Service Performance, already close to these targets, is described in detail in the corresponding Service Definition Document.  

Targeted markets include autonomous driving

This convergence time and accuracy level will make the Galileo HAS particularly useful for autonomous driving applications, providing a much more accurate position and – even more importantly – more stable correction signal. 

Other target markets for the Galileo HAS include geomatics, agriculture, aviation, road, consumer solutions, rail, maritime, inland waterways and space applications.

 “High accuracy is primarily used in professional applications such as surveying, precision agriculture and civil engineering, amongst others,” concludes da Costa. “However, new and emerging applications, including autonomous driving, unmanned vehicles, robotics and a range of location-based services will all demand high accuracy – and the Galileo HAS is set to deliver.”

In conclusion, in its first year, the Galileo High Accuracy Service (HAS) has revolutionized global positioning, offering decimeter-level accuracy for free. Evolving towards faster convergence times and supporting applications ranging from autonomous driving to precision agriculture, the Galileo HAS is set to redefine high-precision GNSS services on a global scale.

You can learn more about the Galileo HAS here. 

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