Current Challenges (and Solutions) in Satellite Navigation

Current Challenges (and Solutions) in Satellite Navigation Omar García Crespillo Institute of Communication and Navigation •Navigation: automotive, aircrafts, shipping, space •Geodesy: surveying, mapping, geology, archaeology, civil engineering, topography •Time keeping: mobile communication •systems, internet traffic •Search and Rescue (SAR) •Fleet management •Traffic control •Geolocation based games •Marketing •Social Networks Satellite Navigation – Application Fields •Satellite broadcasts : •orbital data and ephemeris •precise time stamp (atomic clocks) •Receiver measurements: •compares transmission and reception time (flight time) •distance between satellite and receiver. •Receiver placed in a spherical shell: •trilateration •Position + time Satellite Navigation – General Principles Safety of life applications (e.g. Civil aviation) Safety of life applications •Rely more on GNSS in the future (SESAR and NextGen) •Allow for new type of approaches (e.g. curve) •Increment of air traffic density  Reduce distance between aircrafts •Not only accuracy is therefore important  Integrity and availability GNSS Vulnerabilities System Errors: •Satellite clock •Orbital parameters Atmospheric: •Tropo/Ionospheric Storms •Scintillation Interferences: •Unintentional •Intentional (Jamming) Local Effects: •Multipath •NLOS Fake GNSS signal (Spoofing) GNSS Threats •Characterization of Satellite Orbit and Clock Errors System Error Monitoring SIS Verification with High Gain Antenna Experimentation and Verification Network (EV-NET) Detection, Analysis and alert of Ionospheric Events •Modeling of the Ionosphere through the determination of the TEC (Total Electron Content) •Detection of the amplitude and phase of scintillation for multifrequency GNSS measurements Ionosphere Monitoring Prediction Center (IMPC) DLR GBAS Ground Facility L1 L2 L5 BR01 BR02 BR03 BR05 Braunschweig Airport Since 6th May 2014: Javad Delta Receivers with GPS (L1 / L2 / L5) + Galileo (E1 / E5a) + Glonass Connected to Leica AR25 choke ring antennas Practical Realization: Complete System FPGAfront end active antenna Virtex-4 Mixer RF filter IFamp I VGA LP filter LNA directional coupler A/DWandler 14 Bit IFamp I RFamp I cPCI embed. PC cPCI RF filter BP filter LO Calibration Signal Array PCI Chassis high-rate processing (DDC, correlation) low-rate processing (tracking loops, array processing, PVT) PRN 19 Beamforming and DOA-estimation in Flight Tests Repeater Tx antenna Repeater Rx antenna Repeater Tx antenna GALANT Antenna LNA Repeater Test Set-Up Direction of Arrival (DOA) Estimation in Repeater Scenario C/N0 DOA Skyplot GNSS Skyplot Attitude Determination ? = Estimated DOAs ? DOAs are estimated using array signal processing Technique – 2D ESPRIT Concept of Joint Attitude Determination and Spoofing Detection Algorithm Error Detection & Exclusion M. Appel, A. Konovaltsev, and M. Meurer, " Robust Spoofing Detection and Mitigation based on Direction of Arrival Estimation," in Proc. ION GNSS+ 2015, Tampa, FL, USA, 2015. Loss of satellites due to maneuvers: Inertial Coasting •Loss of satellites due to maneuvers •Time gap due to restart of smoothing filters Continuity and availability requirements might not be fulfilled Multisensor Fusion ∫ ∫ IMU Turn rates Acceleration Computer Specific force 𝐶𝑏 𝑙 Attitude Computer Position Velocity Inertial Navigation System (INS) GNSS Terrestrial Compass Barometer •Improving the signal-to-noise ration (CN0 improvements of 10 dB possible) •Reliable tracking the Line of Sight (LoS) satellite signal Highlight: Inertial aided array antenna attitude •Accuracy improvement •Low sensitivity to faults/biases •Local and global fault detectability improvement •Availability improvement thanks to the reduction of Protection Levels Multisensor Fusion •It is meant to be a GNSS backup System Alternative Position Navigation and Timing (APNT) Signals under consideration: •Distance Measurement Equipment (DME), eDME •L-band Digital Aeronautical Communications System (LDACS) •Universal Access Transceiver (UAT) •Mode S transponder/1090 Mhz (ADS-B)