Inter-GALAC - Integrated Galileo Application Center
Inter-GALAC (Integrated Galileo Application Center) was a public-private collaboration aiming to develop a number innovative applications for the Galileo satellite network. The project received funding from the “Samenwerkingsverband Noord-Nederland” (SNN, www.snn.eu). Galileo is a GNSS (Global Navigation Satellite System) constellation; the European version of the known GPS network. Galileo offers higher accuracy than GPS as well as new functionality. It is expected that Galileo will be adopted by many companies and institutions as it will reduce their dependence on the US GPS system.
In the Inter-GALAC project, a number of parties based in the north of the Netherlands have joined forces to ensure a position in the Galileo program. The north of the Netherlands has two unique facilities for monitoring the quality of the Galileo network: the Westerbork telescope (https://www.astron.nl/radio-observatory/public/public-0) and the LOFAR sensor network (http://www.lofar.org/). In Inter-GALAC, these two assets have been used to claim a role in the Galileo Reference Centre for the north of the Netherlands.
Within the Inter-GALAC project, three challenging Galileo applications have been investigated. The goal of these applications is to lay the foundation for broad economic activities around Galileo in the north of the Netherland.
The European Galieo satellites can pick up radio signals that are broadcasted by emergency beacons on board of ships and airplanes, or carried by individuals. Using special receiver stations, called Local Use Terminals (LUTs), the source of the beacons is determined using the signals relayed by the satellites. The position is then be transferred to local authorities who can mount a rescue operation. This international system has been operational for more than 3 decades and has saved about 31000 to date.
Currently LUTs are operated using moving, mechanical parabolic dish antennas. Each dish can only receive siganls from one satellite at a time. With the arrival of the Galieo network, a third family of satellites has joint the search and rescue network. To monitor all these satellites would require even more dish antennas. However, using Phased Array Antenna technology (the same advanced technology that is used in LOFAR) it is possible to receive all satellite signal using only one receiver station (a Phased Array Antenna Local User Terminal, or PAALUT).
The aim of the PAALUT workpackage of the Inter-GALAC project was to prepare a consortium of industrial partners that could eventually produce such phased array systems. The ambition of was to make sure this next generation of antennas would be built in the north of the Netherlands.
A decomposition of the emergency beacon system was made in order to derive the capabilities that will be needed to form a production cluster. The following criteria for selecting partners for such a consortium was made:
- Electronic Manufacturing Service supplier – RF PCB
- Electronic Manufacturing Service supplier – digital
- Electronic Manufacturing Service supplier – BGA boards
- Mechanical Machined Parts suppliers
- Sheet metal Parts suppliers
- Mechanical Integrator (assembly mech. Subsystems)
- Radome provider (COTS panels)
- Radome material providers
- System Integrator (Electro / Mechanical integration)
Companies that could potentially fulfil the roles described above have been identified in the north of the Netherlands. Forming an actual production consortium is dependent on activities outside the Inter-GALAC project, and was therefore not done within the scope of the project.
The Galileo Reference Centre (GRC), to be located in the Netherlands, will play a crucial role in monitoring Galileo’s performance. The role of the GRC is to provide the European GNSS Agency (GSA) with an independent system to evaluate the performance of the Galileo network and the quality of the signals in space. The aim of the GAMCO workpackage was to investigate the possibility to use the infrastructure available in the north of the Netherlands to offer service to the GRC.
A new receiver system for monitoring the integrity of the Galileo system in space was developed and installed in the Westerbork telescope. This receiver has the ability to receive all three Galileo bands simultaneously and, combined with the high sensitivity of the Westerbork telescope, is a unique monitoring tool. The ability to receive all 3 band simultaneous is very important for the determination of performance metrics such as code-code coherence. The system was tested extensively and was found to be robust against air traffic communication signals that operate in nearby bands. The signal to noise ratio of the system was, despite the relative low cost components that were used, more than sufficient to measure the Galileo signal and the system can serve as a pathfinder for an all-band GNSS receiver station for the GRC. In addition, measurements can be planned, executed and analyzed fully automatically.
All these characteristics make the Westerbork observatory a unique GNSS validation station. This has been recognized by the GSA, and Westerbork has been selected to perform validation measurements on the Galileo network.
Figure 1: Galileo receiver being installed in a Westerbork dish antenna
Protection against GPS/Galileo
There is a need for safe and reliable GNSS application, such as precise location determination, navigation for land-, sea- and air transportation, police and other organization, as well as time determination. Because the GNSS signals are relatively weak , they are very sensitive for in-band interference, such as jamming (disrupting the signal) and spoofing (misguiding GNSS receivers by sending a fake signal). This can have serious consequences; for instance the navigation of an air craft could be disrupted.
The aim of the NoSpoof work package of the Inter-GALAC project was to investigate whether advanced antenna technology can be used to determine the location of GNSS signals, and prevent spoofing. S[&]T focused on designing the prototype and the signal processing, and Astron developed the prototype hardware and supported the implementation of the signal processing algorithms.
An experimental GPS (since the Galileo network was not yet available) receiver was designed and realized. It is based on Software Defined Radio, allowing flexibility in the design. The receiver can receive and process 2 GPS signals simultaneous. In addition, an experimental beam former was developed and the effects of beam forming were studied. The figure below shows the antennas that were installed at Astron to test the experimental setup.
Figure 2: GPS antennas used in the NoSpoof tests
Extensive tests with the system have shown that it is possible to use simple ‘off-the-shelve’ antennas toclearly determine the C/A code phase, which is a measure of the direction of the incoming signal. Several possible improvements have been identified that can be implemented in a potential commercial development of this technology.
These options have not been further explored within the Inter-Galac project, since that focused on exploratory activities. Further development can be done as part of an industrialization project. ASTRON and S[&]T are in the process to offer the developed technology to the European Space Agency for technology development in the area of “next generation" Galileo and EGNOS reference stations.
The Inter-GALAC project was very succesful. The various activities have led to valuable knowledge in the area of phased array technology and GNSS signal processing. This knowledge is being used by the involved parties to offer new projects to e.g. the GRC and ESA.
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- S&T | www.stcorp.nl | S&T is a technology company that is specialized in processing large amounts of sensor data from complex systems.
- ASTRON | www.astron.nl | ASTRON
is the Netherlands Institute for Radio Astronomy. Its mission is to make
discoveries in radio astronomy happen, via the development of novel and
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- Stiching LOFAR | www.lofar.org | Stichting LOFAR operatest the LOFAR sensor
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