Global Navigation Satellite Systems (GNSS) are already a very important part of aeronautical navigation today and are the fundament of future navigation concepts. With their global coverage and the ability to provide integrity (with and without augmentation systems) they are among the key enablers for advanced air traffic management (ATM) concepts, ensuring that the fast increasing volume of air traffic can be handled efficiently also in the future.

The Augmentation Systems group is conducting research related to different augmentation systems including the Ground Based Augmentation System (GBAS), the Space Based Augmentation Systems (SBAS) and the Advanced Receiver Autonomous Integrity Monitoring (ARAIM) with the focus on aviation sector. The goal is to investigate error sources that can impact the user position, to design integrity monitoring algorithms and develop techniques to detect, mitigate or exclude a faulty element of the system, which could lead to an unacceptable error in the navigation solution.

Our group operates its own GBAS test bed, is regularly conducting flight trials and is actively supporting standardization at institutions such as Eurocae, RTCA and ICAO.

The focus topics include:

• Integrity of the systems including all their components
  The areas of interest include the satellite hardware, the navigation signals, user antennas, as well as the receiver and error propagation through all these components.
• Development of new navigation techniques and services
  A special focus is put on the development of dual-frequency and multi-constellation techniques and the respective integrity concepts. The use of a second frequency and multiple constellations can solve the existing ionospheric issues of the single frequency systems, but yields to different error sources that need to be taken into account.
• Ionospheric aspects
  Ionospheric disturbances remain an issue for aviation because they may degrade the accuracy, reliability and availability of the GNSS systems used to navigate.  Therefore a thorough understanding of the processes is developed for appropriate threat modelling and threat mitigation by advanced techniques and leveraging of different monitoring networks.
• Future air traffic management in urban airspace
  The areas of interest include the use of the existing concepts to applications of unmanned aerial vehicles (UAVs) and definition the requirements needed.  Concepts of differential navigation are combined with other methods in order to meet the demanding requirements in terms of cost, weight and reliability. The goal is to ensure safety of the increased use of small and medium-sized aircraft in urban airspace in the future.
  The experience gained in aviation can be extended also to other safety of life applications.

GBAS Flight Tests with ATRA	View from the cockpit during flight test
DLR GBAS Test Bed	CityATM flight campaign
Video DLR GBAS

Ongoing projects:

• DUFMAN (Dual Frequency Multipath Models for Aviation): EC funded project that aims the development and standardization of airborne multipath models
• GUIDE (GBAS Guided Departures): internal funded project which focuses on the development of dual-frequency dual-constellation GBAS and its use for guided precision departures
• DARP (Development of an Advances RAIM multi-constellation receiver)
• CityATM (Demonstration of Traffic Management in Urban Airspace)
• SESAR 2020 (Single European Sky Air Traffic Management Research Programme) is a European initiative aimed at modernising and harmonising the European Air Traffic Management with the goal to ensure the sustainable, safe and efficient development of air traffic in the future.