The European positioning system Galileo will be put into operation in the coming years. The signals we receive on the ground come from a frequency generator developed and produced by Kongsberg Norspace in Horten.
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Ove Ronny HaraldsenGroup Communication Manager
Galileo is Europe’s answer to the American Global Positioning System (GPS) and the Russian GLONASS. Galileo has been developed by the European Space Agency (ESA). When fully developed, Galileo will be made up of 30 satellites and will provide global coverage. All areas of the globe will be covered by at least four satellites at all times, making it possible to determine exact positions and times. The Galileo navigation system will be even more precise than GPS and GLONASS.
TWO BOXES FROM HORTEN
At the centre of these satellites are Frequency Generator and Upconverter Units (FGUU) and Search and Rescue Transponders (SARTs) from Kongsberg Norspace in Horten. Project Manager Roger Spangelid explains the function of the FGUU on board the satellite. “Each satellite has several atomic clocks on board. The signals from these clocks are sent to a clock monitoring and control unit (CMCU). We receive a very pure clock signal from this unit. This signal is further converted and sent to the Navigation Signal Generation Unit (NSGU). The computer adds all the navigation information and sends it back to our unit in three different channels. Then the signals are sent from our unit down to the ground where we can determine our exact position with, for example, a handheld GPS receiver or a mobile phone. Galileo, the American GPS and the Russian GLONASS will function as independent systems”
All systems use the same frequencies, meaning a common receiver can be used. For users of satellite navigation, Galileo will mean a significantly improved service than that which can be achieved with GPS and GLONASS, particularly in mountainous terrain, deep valleys and built-up areas. Coverage in the Nordic areas will also be better and more precise. “The satellites in Galileo will take a slightly different path to the American GPS satellites. The signals will increasingly come directly from above, making it easier to transmit precise signals in narrow streets, between high rocky walls and in dense forests”, explains Spangelid.
EXTREMELY WEAK SIGNALS
Kongsberg Norspace is currently the world leader in dealing with the type of signal processing used in the units supplied to Galileo. What makes Norspace unique is the technique behind the SAW filter. SAW stands for surface acoustic wave and is a technique that was developed in the 1980s when the company recognized its potential. Norspace has technology that manages to distinguish weak signals that are buried in large amounts of noise. This is a particularly important property for Search and Rescue Transponders that are intended to capture signals from emergency beacons. “You should be able to use the satellite to calculate the location of the person in distress. There may be extremely weak signals or other interference in the same frequency area, Good filtering is therefore essential. We have to identify what is important and amplify it”, explains Spangelid.
NEXT GENERATION
Many of the components are also made at the Norspace premises in Horten. Testing the components and final inspection take longer than assembling the actual boxes. K Magazine was allowed into the clean room where much of the testing is done. There are chambers here that simulate vacuum and temperature conditions to which the components will be exposed. The parts are vibration tested and tested for electromagnetic compatibility. Norspace is a subcontractor of Surrey Satellite Technology in England, where the two boxes will be delivered following final verification. The satellites will be assembled at OHB in Germany.
Norspace says it has a seamless partnership with its customers and now aims to be part of the next generation of Galileo satellites. That’s according to Sverre Bisgaard, CEO at Kongsberg Norspace. “Work on getting into the Galileo project started as far back as 1999. It was important to get in early in order to influence the type of technology that would be used. We are currently aiming to be part of the next generation of Galileo satellites and are involved in all phases of development”, says Sverre Bisgaard.
