To meet the challenges of future Air-Traffic Management (ATM), aeronautical communication and navigation technologies are currently modernized. In communications, the air-ground communications standard LDACS (L-band Digital Aeronautical Communications System) is under development. The main goal of the DLR internal project LDACS-NAV (LDACS Navigation) is to advance the LDACS technology candidate LDACS1 to include navigation functionality. The feasibility of this approach is proved by in-flight measurements.
In aviation, navigation will more and more rely on Global Navigation Satellite Systems (GNSS), like GPS or Galileo. To back-up GNSS and to have available alternative navigation means in the GNSS failure case, so-called Alternative Positioning, Navigation, and Timing (APNT) systems are required. Efficient and cost-effective APNT solutions might be provided utilizing signals-of-opportunity, i.e. utilizing available signals originally introduced for other purposes. The LDACS1 ground station signals constitute a set of signals-of-opportunity well-suited for ranging. Thus, advancing LDACS1 to include navigation functionality is an interesting approach for APNT.
The LDACS-NAV project has three distinguished working areas:
The in-flight measurement campaign of the LDACS-NAV project is of special interest. It is scheduled for November 2012 and shall prove the suitability of LDACS1 for APNT in a realistic environment. Four ground station sites are set-up which transmit LDACS1 signals synchronized to each other in time. The signals are recorded onboard the measurement aircraft, a Dassault Falcon 20-E5. The geographic locations of the ground stations and the aircraft routes are chosen as to allow for realistic measurement scenarios. The data gathered at the measurement aircraft by means of a respective data grabber and storage device are evaluated offline after the in-flight measurement campaign. Aircraft positions are calculated from the measurement data and compared to the true aircraft positions. The goal is to prove that aircraft positions can be determined with accuracy sufficient for APNT, i.e. that the determined aircraft position accuracy complies at least with RNP0.3. RNP is the Required Navigation Performance given in nautical miles.
Project Details
Project Start: October 2011
Project Duration: 27 month, until December 2013
Project Manager: Dr. Dmitriy Shutin
Support: DLR Internal Project (Programmdirektion Luftfahrt, Technology Marketing)