European Galileo satellite systemJon Monks
On 25 July 2018, the European Space Agency launched the last four satellites for the European Galileo satellite navigation system.
The European Galileo satellite system comprises 24 satellites in total and took 13 years to get in place. The launch of the first satellites began in 2005.
Overview of the European Galileo satellite system
The Galileo satellites orbit at an altitude of 29,600 km from the earth’s surface. The Galileo satellites appear as a fixed point in the sky this is, like both the US and Russian satellite systems they can be used to navigate within the outdoors with both handheld and wrist-based GPS devices.
All the Galileo Satellites have just been launched from the Kourou site in French Guyana in an Ariane 5 rocket and satellites must be replaced after about 15 years. This is primarily owing to the fragile atomic clocks on board. The system was originally only to be used for civilian purposes but is now also being directed for military use. The satellites that were launched first will already be due for replacement next year.
Accuracy down to 20 cm – but not for all users – European Galileo satellite system
The Galileo system has greater accuracy than the current version of the American GPS. For general use, Galileo has an accuracy of less than a meter (GPS: three meters), but the high-accuracy service with encrypted signal provides position detection down to an accuracy of 20 cm.
When Britain leaves Europe this is the area of the Galileo GPS system that the UK will be unable to use the encrypted signal that gives this accuracy.
Because the exact location of the satellites is known, the receiver can calculate its own position based on the time difference of the signals it receives from at least three satellites.
The satellite signals reach the receiver in less than one-tenth of a second. To measure the time difference accurately, the satellite navigation uses a specially coded Pseudo-Random Noise signal.
Atomic clocks ensure that each satellite sends its own PRN code at exactly the same moment as the rest. This is how such good accuracy can be given, which is not able to be done with the existing GPS and Glonass systems.
Outdoor GPS devices that utilise the European Galileo satellite system
Since late 2016, Galileo has been sending a navigation signal. There is now a whole series of user devices that work with Galileo including both Garmin and SatMap Outdoor GPS devices both handheld and wrist based (GPS Watches) devices.
The use Galileo website list all the current devices that use the satellite system for navigation.