Testing GNSS Systems and Devices David Pearce Simplifying the - PowerPoint PPT Presentation

Testing GNSS Systems and Devices David Pearce

Simplifying the integration of Position, Navigation, and Timing technologies into mission-critical systems. • High-End Commercial Apps • Military / Aerospace • Datacenters • UAVs • Robotics/Telematics • Electronic Warfare • IDM • C4ISR • GIS Data Mining 2 GNSS Testing 1/13/2017

Testing GPS Systems & Integration

GNSS Test Methods 4 GNSS Testing 1/13/2017

Simulation Record/ Live GNSS Test Methods Replay Sky True real life constellation replication X X X Repeatable tests X X Replay fixed scenarios ”that has already happened” X X Modify parameters during test X Scenarios that have ”not yet happened” X Simulate events (satellite drop out, change received X signal strength, etc) Simulate multipath X Simulate noise and test sensitivity X Simulate leap second X Test performance with future systems X 5 GNSS Testing 1/13/2017

Basic Test Cases • Sensitivity • Acquisition • Tracking • Re-aquisition • Time to First Fix (TTFF) • Location Accuracy • Stationary • Dynamic • Trajectories • Time Transfer • Leap Second 6 GNSS Testing 1/13/2017

Time to First Fix Almanac Ephemeris Position/Time 1. Receiver warm-up time Cold Start No No No 2. Acquisition time Warm Start Yes No Yes 3. Settling time for code and carrier Hot Start Yes Yes Yes tracking 4. Navigation data read time Almanac • 5. Time to compute the navigation Orbit and status information for EVERY satellite • Each satellite transmits the entire almanac • solution Ionospheric model • Leap second information • 6. Time the retrieve the system time 1/25 of the Almanac data is transmitted in the navigation message • Takes 25 complete navigation messages to receive entire almanac (12.5 • reference minutes) Considered valid for 180 days • Understand cold vs warm vs Ephemeris • Orbital information for each satellite hot start is critical when • Each satellite only transmits its own data • generating GPS RF Considered valid for about 4 hours • 7 GNSS Testing 1/13/2017

Time Transfer • Time accuracy • Leap second handling 8 GNSS Testing 1/13/2017

Impairments to GPS • Multipath • Interference • Signal fading 9 GNSS Testing 1/13/2017

Test Susceptibility to Jamming and Spoofing

What is IDM and GPS Spoofing? Interference Detection and Mitigation for improving resiliency of PNT Types of GPS/GNSS Interferers: • Accidental / Intentional Intentional Unintentional Jamming Spoofing Jamming (easy to do) (harder to do) Jamming Spoofing Easy to Detect Difficult to Detect! In either case, after detection, there are various mitigation techniques • 11 GNSS Testing 1/13/2017

Jamming & Interference • Interference: radio-frequency signals that interfere with the ability of the GNSS receiver to extract GNSS signal information from the background noise • Jamming: Intentional Interference • PPD: Personal Privacy Device 12 GNSS Testing 1/13/2017

Testing Jamming Jammer Types Simulating Jammers • CW – choose frequency based on • Majority of PPD jammers are chirp GNSS constellation jammers • Simulates the CW type jammer • GPS L1 Frequency – 1.57542GHz • Noise – set bandwidth around center • Common Sweep Period – 9us frequency • Bandwidth 1kHz (CW) – 44.9MHz, 20MHz • Simulates the narrowband jammer is typical • Sweep – set sweep time 4µs – 20µs • Also available • Simulates the chirp jammer • Narrowband Jammers • All GNSS frequency bands can be • CW Jammers simulated • Location Based Jammers 13 GNSS Testing 1/13/2017

Use Case 1: Jamming a Receiver for Navigation • Receiver alone • Example setup: • Simulator used for GNSS signals + jamming signals • When the jamming signal is applied navigation is lost 14 GNSS Testing 1/13/2017

Use Case 2: Jamming a Receiver+ IMU for Navigation • Testing a Geo-PNT (Receiver with IMU + timing outputs) • Example Setup: • Simulator used as a jamming source with live sky signals • When the jamming signal is applied, the IMU allows navigation to continue 15 GNSS Testing 1/13/2017

Use Case 3: Jamming a Timing Receiver • Testing a Timing Receiver • Monitor the 1PPS signal Using a frequency counter monitor the 1PPS signal of the device-under-test against a stable 1PPS reference • 1PPS signal is stable until the receiver is jammed (900 seconds after the start of test) • The 1PPS becomes unstable as the receiver tries to overcome the jamming signal • 16 GNSS Testing 1/13/2017

Why is Spoofing so difficult? Spoofing requires replicating attributes: 1. TIME SYNC Signal matched to satellite transmission 2. POSITION Accuracy requires real-time tracking of victim location 3. POWER Level controlled in real-time to match receiver An “perfect” spoofer would be indistinguishable from the Live Sky signal! 17 GNSS Testing 1/13/2017

Hardening GPS/GNSS Systems What happens to your system if GPS/GNSS is spoofed? • Malfunction? Fault? • Position drift? • Does it issue an ALERT or does it just FAIL SILENTLY? • Time sync drift? • Which is worse? 18 GNSS Testing 1/13/2017

GNSS Simulators 19 GNSS Testing 1/13/2017

GNSS: Multi-Frequency, Multi-Constellation Constellations Frequency Bands 1 2 3 4 Global GPS L1/L1C L2/L2C L5 GLONASS L1 L2 E5 Galileo E1 E6 Beidou B3 B1 B2 Regional QZSS L1 L2C L5 L5 IRNSS SBAS WAAS EGNOS MSAS GAGAN 20 GNSS Testing 1/13/2017

GSG-5/6 Series GNSS Simulators Accurate Powerful Affordable Easy to Use 21 GNSS Testing 1/13/2017

GSG Family of GNSS Simulators • Powerful Up to 64 independent satellite channels • GPS L1, L2, C/A, P-Code, P(p-Y), L2C and L5 • GLONASS L1 and L2 • Galileo E1 and E5a/E5b • Beidou B1, B2 • SBAS (EGNOS, WAAS, MSAS, GAGAN) • QZSS L1 C/A, SAIF, L2C, L5 • IRNSS L5 • White noise generation • Multipath, interference and jammer simulation • Utilizes RINEX navigation data, and optional ALM and e.g. NMEA files as inputs • Logs RINEX obervation data, almanac, NMEA and more • High accuracy time base • Programming interface for automated testing • Accurate, variable output level from –65 to –160 dBm, and more • 22 GNSS Testing 1/13/2017

GSG Family of GNSS Simulators • Affordable Modular architecture sets new industry • performance/price standards High performance R&D lab simulator features • Priced to support efficient production applications • and use as a common engineering tool • Easy to use Create versatile scenarios • Full I/O control from intuitive front panel User • Interface GSG StudioView™ PC-based software with Google • Maps interface Remote operation via a web-based interface or via • SCPI commands 23 GNSS Testing 1/13/2017

Vulnerability Test System 24 GNSS Testing 1/13/2017

Summary • Simulation allows full testing of systems with integrated an GPS/GNSS receiver • Mission-critical applications require a high degree of operational validation when transitioning to a new receiver • A simulator capable of performing the necessary tests for the application will greatly simplify the integration of an GNSS receiver 25 GNSS Testing 1/13/2017