Galileo gets faster for every user

The improvement comes from the so-called Enhanced Navigation Message (I/NAV), which was first displayed on the two newest Galileo satellites launched in December 2021 and entered service last summer. ESA as the design body for the Galileo system has contributed to the I/NAV deployment from the design phase, implementation on the satellite and ground segment, qualification for implementation and on-orbit testing.

Galileo’s service provider, the European Union Space Program Agency, EUSPA, has now upgraded all other Galileo FOC satellites in service to broadcast this improved navigation message.

The upgraded navigation message improves the time it takes Galileo to reach first position by a factor of two or three – depending on whether the recipient is in more challenging rural or urban environments.

This is made possible by improving the message’s ability to correct decoding errors and recover lost data. At the same time, receivers can also gain faster access to highly accurate Galileo system time without having to decode the entire navigation message.

ESA uses the Galileo Time and Geodetic Validation Facility – an independent network of observing stations around the world – to validate broadcast data and associated performance. Their analysis showed that all broadcast data is correct. The measured performance of the new data is also fully in line with the performance targeted in the design phase.

Meanwhile, ESA’s Navigation Laboratory, based at ESTEC in Noordwijk, the Netherlands, has deployed a pair of communications and navigation test vehicles on flights across the Dutch countryside to central Rotterdam to confirm the performance improvements available to users in a variety of environments.

These test vehicles include a variety of satellite navigation receivers as well as cameras and sensors to record all the details of their surrounding environment.

“Galileo signals provide the most precise resolution in the world, down to decimeter accuracy,” explains Stefan Wallner, Head of ESA’s Galileo G1 Signal Space Engineering Unit.

“In order to benefit from the excellent accuracy of the Galileo system, the user also has to retrieve the corresponding navigation message from the Galileo signal even in difficult user environments – so the faster the better. In the Galileo navigation message, there was sufficient backup data capacity available To address this improvement.

At the same time, these new elements in the “I/NAV” message must be fully compatible with the old receivers, so that the update has no impact on their operation and performance. Before the start of the deployment, ESA in cooperation with EUSPA and the Joint Research Center (JRC) of the European Commission carried out extensive test campaigns involving a large number of commercial Galileo receivers and successfully demonstrated that the new I/NAV message indeed had no negative impact on them.”

I/NAV improvements are based on three innovations.

• the Improved time to fix first place It comes about by reducing the amount of information the receiver needs to create the first position correction, at the cost of lower initial accuracy in turn. This results in the first fix within a few seconds, with an error range of less than 4.5 metres, which in turn decreases further until the usual sub-meter level accuracy is reached after the complete Galileo navigation message is received.
• i/navigation Improved durability It comes from a new coding method that introduces additional redundancy into the navigation message, so that any lost or corrupted data – perhaps obscured by tall buildings or reflected in polished artificial surfaces – can easily be recovered.
• finally, Galileo system time It is made available to receivers without having to completely demodulate the navigation message by presenting it as a “secondary synchronization mode” within the message, and can be accessed within a few seconds. This is of particular interest to recipients who retrieve the Galileo navigation message over the Internet or parallel networks, thus missing just the correct link back to Galileo time to provide the first fix.

The data collected during the current monitoring campaign is being used to implement a set of recommendations for chip manufacturers to maximize the effectiveness of the use of I/NAV signals.

All information needed to implement and utilize the I/NAV message optimization can be found in the Galileo Open Service Signal in the Space Interface Control document. The next version of the Galileo Open Service Definition document will also provide a description of the expected performance to be obtained from the enhanced I/NAV message.

About Galileo

Galileo is currently the world’s most accurate satellite navigation system, serving four billion users worldwide since entering initial services. All smartphones sold in the European Single Market are now guaranteed to support Galileo. In addition, Galileo makes a difference in the fields of railways, maritime, agriculture, financial timing services and rescue operations.

Galileo is one of the flagship programs of the European Space Programme, managed and funded by the European Union. Since its establishment, ESA has been leading the design and development of space and ground systems, as well as launch operations. EUSPA (European Union Space Programme Agency) acts as Galileo’s service provider, overseeing market and application needs and closing the loop with users.

For more information about Galileo: https://www.usegalileo.eu/EN/.