SOSTAR-X
SOSTAR is the abbreviation for S tand- O ff S urveillance and T arget A cquisition R adar roughly translated as "Detachable surveillance and target search RADAR. SOSTAR-X is the installation of an experimental system in the prototype 001 of the Fokker 100 aircraft.
The program is financed by the European nations Germany, France, Italy, Spain and the Netherlands, summarizes the activities and technologies for Synthetic Aperture Radar (SAR) in these countries with the aim of a certain independence in their own countries and NATO from of American technology.
It is part of American policy to be very restrictive, even with friends, when it comes to passing on technologies that are used to obtain information (“information dominance”). In accordance with the contract , information obtained in NATO's AWACS aircraft is filtered by the USA until it is passed on to the partners involved, at least with a delay.
Although the technology was used early on in Europe and Germany at the Dornier works for the ERS satellite , the USA has also used the technology in aircraft with Joint STARS for surveillance and reconnaissance. England is currently purchasing such aircraft under the name ASTOR in the USA.
Analogous to the AWACS aircraft that monitor the airspace, Joint-Stars monitors the ground in real time, i. H. the results are available immediately and digitally and can be passed on to the responsible departments without delay. As part of its new tasks, NATO wants to observe crisis areas from the air, but does not want to procure the now outdated Joint Stars aircraft.
In the meantime, the transatlantic NATO partners respond to the NATO tender ( Alliance Ground Surveillance ) with a common radar system ( TCAR ), whereby SOSTAR is introduced as a recognized European component.
Germany wants to use this SAR technology in the planned unmanned system called EuroHawk .
Synthetic Aperture RADAR (SAR)
SAR technology uses the well-known physics of radar in conjunction with extensive and fast data processing. Explained in roughly simplified terms, not only the width but also the height is read from the reflected signal from the object on the ground, which is illuminated by the radar, resulting in photo-realistic 3D images. Further algorithms can calculate the movement of the object. In this way, precise images and contour lines can be recorded. In the mid-1990s, Dornier-Werke flew the countries of Indonesia and Thailand with the DO-SAR, thus providing the basis for precise maps of these countries.
The advantage of the method compared to photographic recordings is that the position, the height and, if it has moved, the speed for each point of the image was measured and can be read out. The result is practically in real time; H. in the aircraft and can be given to other users via data links / satellite radio. Another advantage is that these radar measurements can be carried out well over 100 km away from the object in cloudy, rainy and night conditions and always provide the same clear image. The higher the aircraft flies, the greater the range, as the SAR follows the rules for optical visibility.
In reality, the technical effort is not that simple. The core element is the radar antenna, which consists of thousands of small transmitter and receiver modules (transmitter / receiver modules, TRM). The more modules the antenna has and the longer it is, the greater the range and accuracy. The modules require a lot of electrical energy and cooling and, since the antenna is rigid and does not rotate like classic radar antennas, electronically swivel the radar beam laterally (Active Electronic Scanning Antenna, AESA). The electronics also allow the concentrated scanning of smaller areas, the so-called spot mode, with an even better resolution. In the future, the TRM should be produced as cheap and lightweight micro-elements.
Since the ground is scanned at the speed of the aircraft in a strip of over 10 km and more, large amounts of data are generated. The data processing on board has to be efficient and fast. With several alternating aircraft, larger crisis areas in the form of entire countries can be observed 24 hours a day 365 days a year without interruption.
Other algorithms determine the deviations from the previous flight / scan and eject the changes in the image. This technology has been used for a long time on satellites with SAR on board to reduce the evaluation effort.
In contrast to airplanes, satellites can only fly over an area of interest at fixed times. Furthermore, the resolution of the images is lower due to the height. Both systems, satellites and aircraft, complement each other. Satellites take over long-term observation, airplanes then do concentrated monitoring.
This technology also works above water, but additional algorithms for inverse display (ISAR) are necessary here, as the radar Doppler effect is limited over water. Further algorithms can be derived from the outlines e.g. B. automatically determine the type of ship, vehicle, helicopter, etc.
SOSTAR-X
SOSTAR-X is a SAR demonstration system that the countries listed above have been developing together with their national industries since 1999. The aim was to bundle the developments existing in the individual countries and to create a future-proof system using the latest technologies. Only in this way was the USA ready to enter into transatlantic cooperation for the needs of NATO.
The aim in Germany is to have a SAR system for use in the unmanned EuroHawk aircraft . The task is to also present the system in flight and to prove its function.
However, the SOSTAR-X is not yet a system that is operationally ready. For budget reasons, the focus was placed on the development of the key components of the antenna and some determining data processing components. The antenna was also not built to its full length, but it is designed in such a way that it can be modularly expanded to any desired length and equipment. For use e.g. B. in the unmanned UAV EuroHawk, the SOSTAR-X capacity is even sufficient.
The prototype of the Fokker 100 aircraft was offered as a carrier for the flight tests. This aircraft is operated by Stork as a reference aircraft for servicing the many Fokker 100 aircraft that are still flying around the world. This aircraft still has all the test equipment from the approval process in the form of ballast tanks, computer racks and workstations on board. For testing the SOSTAR-X you had only under the forward fuselage with some reinforcements the antenna and the streamlined radome ( radar dome ) grow.
The computers for data processing are built into the existing racks. With the use of commercially available computers, the workstations certainly do not fulfill the idea of operator workstations in reconnaissance aircraft, but that was not the point.
As an international program, the participating governments and the companies involved created executive management organizations. The countries of France, Germany, Italy, the Netherlands and Spain have set up the SOSTAR Steering Committee, based at the Federal Ministry of Defense in Bonn, as the central client body in a government agreement. On the contractor side, the companies Thales, EADS / Dornier, FIAR, Dutch Space and Indra founded SOSTAR GmbH, based at Dornier (now EADS) in Friedrichshafen, as the main contractor, which is responsible for the individual work on project management at the companies mentioned and their other subcontractors forgave. A ring laser navigation system from iMAR GmbH, Ges. Für Inertiale Navigation / Germany was used as the inertial navigation system, which is required for the highly precise determination of position, speed and position angles in real time.
termination
On September 26, 2007, at the DGA in Cazaux France, a final presentation took place on the ground and in the air in front of senior government representatives from the participating nations. The full scope of services was verified and the project ended. A continuation or practical application was not decided because in the meantime NATO has changed the Allied Ground Surveillance (AGS) project with a manned aircraft in favor of an unmanned solution and the USA is pushing for a complete delivery of its Global Hawk . The nations participating in SOSTAR-X could not agree on a competing further development of the SOSTAR-X radar for the Global Hawk. Stork Fokker has announced that the aircraft will be scrapped after removing the SOSTAR-X devices, as further or other operational tasks could not be acquired.