Tuesday, June 6, 2023


GPS and Galileo are built into most navigation systems in the European Union

On January 8, 1642, the scientist who laid the foundations for developing the current navigation systems died. Galileo Galilei invented the telescope, discovered that the Earth revolves around the Sun and that the planets have satellites. But today Galileo, in addition to being a scientist, is the name that the European Space Agency (ESA) has given to one of its star programs: the positioning system for all citizens.

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Galileo Gaslilei (1564 -Arcetri, Tuscany; January 8, 1642)

In Europe we have been hearing about Galileo for years without really knowing where he is. But it turns out that Galileo has gotten older. He is already 22 years old, although we still do not know what he does. Javier Benedicto, director of the Galileo program at the European Space Agency, assures that Galileo is more present in our lives than we think.

Javier Benedicto, director of the Galileo program at ESA

Javier Benedicto, director of the Galileo program at the European Space Agency.

We have been hearing about the Galileo program for many years.

– Javier Benedicto. The Galileo navigation system began development in the European Union just over 20 years ago. It is a global coverage program that offers positioning and synchronization services to all citizens, wherever they are. It reached its culmination in 2016.

Q- What is the difference with the American GPS ?

JB- GPS offers an accuracy of between 10 to 30 m. With Galileo we talk about less than the meter. And that opens up endless possibilities at the level of the applications that we can offer. GPS is also under the control of the United States Department of Defense and, with few exceptions, its applications are fundamentally military. Galileo, however, is a civil system and has therefore been developed for eminently civil purposes. That at the level of the programmatic aspects. In terms of performance, Galileo is much more modern because it is recently manufactured and relies on more advanced technologies. That reverts to the quality of the service.

Galileo accuracy is less than one meter, GPS accuracy up to 30 meters

Q- What does that quality translate into?

JB- In a centimeter precision.

Q- There are times when more is necessary, pinpoint precision

Yes effectively. For example, cartography to make maps . For those cases, there are systems called differentials in which, by waiting a minute or two, millimeter precision is achieved. They are services that are offered to private companies for payment. There are also solutions of this type installed locally. For example, to enter large seaports or airports to help aircraft make automatic landings based solely on satellite navigation.


One of Galileo’s satellites.

Q- Is there some kind of rivalry with GPS?

JB- In 2004 we signed an interoperability agreement with the US State Department so that Galileo and GPS were compatible. In other words, any receiver, without major modifications, can receive both navigation systems at the same time. Galileo is, in fact, the only system that has been licensed in the United States. Neither the Chinese nor the Russian program is. This is why most semiconductor manufacturers have integrated Galileo together with GPS in their products.

Galileo, a matter of time

Q- GPS is still used in cars and mobile phones. Can I ask the manufacturer to install Galileo for me?

JB- Virtually all browsers today have the Galileo function incorporated even though the consumer may not know it. Car and phone browsers work with both. The receiver is the one that determines at all times whether it uses two GPS satellites and three Galileans or four Galileans and no GPS. That is, you decide the best possible combination to provide great precision at a specific time and place. The compatibility between the two is a very important aspect.

Q- But nobody is aware of the importance of Galileo. Everyone thinks that what they carry in their car or on their phone is GPS.

JB- GPS has become a brand, like when you drink a soda and say that you have had a Casera. The same thing happens with positioning systems.

Q- If Galileo is more advanced, what need does it have to coordinate with GPS?

JB- The signal received from the Galileo satellites is more powerful and has better precision in itself, but it must be taken into account that the positioning calculations also consider the height. It is a fundamental value, for example, for air navigation or for those who have to be located in the mountains. For that you need four satellites. Why four? Because in addition to determining three coordinates, you have to solve the time variable.

Galileo takes into account the time it takes for the signal from the satellites to reach Earth. An error of just one billionth of a second equates to a 30-meter deviation in positioning.

Q- How does the weather influence here?

JB- A specific position is determined by calculating the time it took for the signal from leaving the satellite until it reaches the receiver. For this reason, in all Galileo satellites there are very high precision clocks that allow to determine this time with great precision. What the receiver does is look for the best four at all times. And that varies because satellites They are not in geostationary orbit, but are moving with respect to the user who, in turn, is moving as well. For this reason, the geometry of the constellations of the GPS and Galileo navigation systems is changing. The receiver decides which are the four best satellites at all times. This is how it works. An error of just one billionth of a second equates to a 30-meter deviation in positioning.

Q- It is to be assumed that Galileo will have a fundamental role in autonomous driving

JB- This extreme precision we were talking about will be necessary here. Autonomous driving requires a lot of reliability. Autonomous vehicles must be positioned in an environment where there will be other cars in motion. It is also necessary to determine aspects such as how many centimeters we are from the edge of a road or any road infrastructure. And Galileo will be decisive in all this.



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