Using Pseudolites as a Flightlanding System

Jens Henzler, Martin Weiser

Abstract:	Terrestrial transmitters that radiate signals which are compatible to those of existing satellite navigation systems are called Pseudolites (pseudo satellites). As local augmentations to GPS, GLONASS or GNSS2 they play a role in the current concept for the realisation of ICAO Cat. III landing systems. At the Institute of Flight Guidance and Control of the Technical University of Braunschweig a pseudolite system has been invented, that has been tested in first flight trials. It is based on a group of Pseudolites that is located in some distance of the runway directly in the approach corridor. During a fly over they allow for an exact position determination. Due to these measurements the inertial sensors onboard the aircraft can be calibrated in an accurate manner. These are then used to ensure the integrity during the final approach phase of the flight. A further application can be seen in the augmentation of a GNSS based taxiguidance system when installing Pseudolites in the terminal area in order to guarantee a sufficient geometry. The system consists of GPS simulator cards that are modified in an appropriate manner to be used as terrestrial navigation transmitters. In order to process the signals a 199 GPS receiver is used which software has been modified in such a way that it allows for the reception of pseudolite as well as satellite signals. A physical restriction for the reception of a pseudolite signal is given by the near far problem. Due to this feature it is only possible to receive the pseudolite signal in a limited area without loosing the satellite measurements. To counteract this restriction the pseudolite signal was modulated with a special navigation data format that allows for a quick acquisition. In the course of this paper, the pseudolite system of the Institute of flight guidance and control will be introduced. Further the results of the first flight trials will be presented.
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	199 - 207
Cite this article:	Henzler, Jens, Weiser, Martin, "Using Pseudolites as a Flightlanding System," Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999), Cambridge, MA, June 1999, pp. 199-207.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In