Testbed for dual-constellation GBAS concepts

Satellite based Navigation Systems (Global Navigation Satellite System GNSS) will become a major element in the navigation infrastructure of the future. In addition to classical en-route and terminal navigation, where GNSS is increasingly used, approach and landing procedures are being developed and implemented based on GNSS. To meet the requirements of integrity, accuracy, continuity and availability for precision approach and landing operations, augmentation systems are needed. Currently there are two augmentation systems for these periods of flight available: Ground Based Augmentation Systems (GBAS) and Space Based Augmentation Systems (SBAS). At the research airport of Braunschweig a Galileo Test Environment called "aviationGATE" is currently under development by the Institute of Flight Guidance (IFF) of the Technische Universitat Braunschweig, using a total of 9 ground located transmitters to cover an area of up to 5,500 squarekilometres. Each of these ground transmitters is able to send three navigation signals in both frequency bands (I/NAV on Elb and E5b, F/NAV on E5a) or freely defined contents. First components are in a test stage. Based on the different experiences with GBAS data gathering campaigns in the past, this test bed will be further developed and optimized. An initial concept has already been designed and will be discussed in the paper which includes among others the implementation of an aircraft positioning module and an aviationGATE correction message uplink module. With the coverage area including the airport as well as the already implemented GPS approaches, this test bed will serve as an ideal environment for tests of GBAS CAT II/III dual constellation concepts. This paper will describe the "aviationGATE" at the research airport of Braunschweig with its capabilities and its planned expansions towards a test bed for GBAS dual-constellation research. The possibilities and limitations of such a test environment for early GBAS GAST-D system concept evaluations will be discussed.