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Research

The Institute of Geodesy and Navigation has carried out research for almost 20 years now and has been able to provide significant contributions to science and technology in the fields of Geodesy and Navigation. For instance, the concept of Operational Geodesy ("Integrated Geodesy") was developed and optimised in the early days after the foundation of the Institute resulting in the integrated software package OPERA. High precision inertial navigation and GPS/INS integration as well as pseudolite research have been and still are important research foci. Several software packages were written for major GPS manufacturers which are now in world-wide use.

The Definition, Development and Optimisation of the Civil European Satellite Navigation System GALILEO is one of the most important research topics currently dealt with at the Institute of Geodesy and Navigation. The FANS II Committee of ICAO stated that only a civil Global Navigation Satellite System (GNSS) is able to meet future requirements of airborne traffic during the flight phase and, in particular, during the CAT II/III landing approach. Studies are currently carried out defining and investigating a future GNSS called GALILEO. Current research efforts are devoted to the definition of the GALILEO signal structure, the investigation of possible synergies between positioning using mobile phone networks like GSM/UMTS and a global satellite navigation system like GALILEO as well as pratical experiences within the nation-wide test-bed GATE. Furthermore, the design and development of RTK GNSS receivers for the future GNSS is an important research focus of the Institute. Together with industrial partners, the development of an end-to-end simulator for the GALILEO system has begun recently.

Apart from studies related to future Global Navigation Satellite Systems, a variety of projects deals with applications using the existing GPS System. Some examples of current research covering this branch are precise kinematic positioning for instantaneous sea level height retrieval (see e.g. ENVISAT Cal/Val Campaign), attitude and elevation/heading determination for terrestrial objects as well as for satellites, Receiver Autonomous Integrity Monitoring (RAIM), precise determination of the instantaneous sea surface determination for radar altimeter calibration using GPS in buoys, the development of a real-time DGPS deformation monitoring system and of a CCD/GPS camera systems to determine the deflections of the vertical has been subject of research as well as water vapour estimation of the atmosphere using GPS in static networks and on moving platforms. Work for the European wide area differential system EGNOS (European Geostationary Overlay System) has been subject during the past years.

An important research group of the Institute deals with Sensor Fusion and, in particular, with the Integration of GPS and INS. The availability and/or integrity of the satellite signals alone is not proper for a number of applications in geodesy and navigation. Due to the complementary system characteristics of the sensors of INS and GPS, a performance enhancement can be achieved when both systems are synergistically combined. Several projects are carried out applying loose up to tight coupling of the devices. With help of the highly precise Sagem Sigma 30, the railway track deformation error can be detected and kinematic accelerations can be separated from the gravity field-induced accelerations during airborne surveys. Tight coupling of GPS and INS is one of the most challenging, but also one of the most beneficial integration methods currently investigated at the institute. GPS/INS integration is also an important cornerstone for the airborne gravimetry carried out by the institute since the estimation of aircraft accelerations and thereby the separation of kinematic and gravity field accelerations can be precisely performed. Goal of the Pseudolite Research at the institute focuses on the conception, operation, test and evaluation of a ground-based augmentation system using pseudolites with the aim to support precise landing approaches up to CAT III with differential GPS. Pseudolites are "pseudo satellites" located on the ground emitting GNSS navigation signals and thereby provide enhanced availability of navigation signals.

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