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Session F11: Modeling and Simulation: Results of Strategic Studies

SWAC/NAVWAR Force Design mod/sim strategy: An Overview of SWAC’s High Fidelity PNT Simulation Framework
Ezra Bregin, Johns Hopkins University Applied Physics Laboratory; Hemanshu Patel, The Aerospace Corporation; Daniel DeVargas, USSF SWAC/NAVWAR
Location: Ballroom D
Date/Time: Wednesday, Jun. 4, 4:25 p.m.

The Space Warfighting Analysis Center (SWAC) Spectrum Warfare Program presented a NAVWAR force design during the USSF Force Design Conference (FDCON) in December 2023. The mod/sim approach and findings will be summarized to be share with the JNC community to communicate the approach of the SWAC.
SWAC is responsible for conducting analysis, modeling, wargaming, and experimentation to create and provide authoritative operational concepts and force design guidance for the USSF at large.
This presentation details SWAC’s initiative to develop a high-fidelity PNT simulation framework designed to assess platform resiliency under degraded-PNT conditions. To ensure that the simulation outcomes are representative of real-world performance, the tool incorporates the following models:
1. Controlled Reception Pattern Antenna (CRPA). Two algorithms are implemented, a pure nuller and beam pointing plus nulling.
2. Terrain Integrated Rough Earth Model™ (TIREM™)
3. GPS constellation configurations at various epochs, along with additional GNSS constellations. For the GPS constellation the measured antenna gain pattern is modeled along with signal power and orbital motion.
4. Signal types, such as CA-L1, P(Y)-L1, M-code-L1, P(Y)-L2, M-code-L2, L1C, L2C, and L5C.
5. GNSS receivers, encompassing channels, filters, and state machines.
6. Twelve-State Inertial Navigation System (INS). Inertial Measurement Unit (IMU) measurements are modeled and the appropriate noise is added before being ingested into the INS.
7. Clocks, including Oven-Controlled Crystal Oscillators (OCXO) and Evacuated Miniature Crystal Oscillators (EMXO)
8. Jammers, including high gain jammers pointing jammers and wide beam jammers.
9. Spoofers, including repeaters, single-PRN spoofers, intelligent spoofers, and distributed spoofers
10. Anti-Spoof Techniques, including Receiver Autonomous Integrity Monitoring (RAIM), Advanced-RAIM, INS consistency checks, clock consistency checks, and Tactical-PNTSA.
Following an overview of the framework, the presentation provides an in-depth analysis of platform performance to underscore the importance of enhancing simulation fidelity. Special attention is given to the CRPA model, TIREM, and anti-spoofing techniques. The CRPA model, which dynamically computes the weights for each element to minimize the J/S ratio, is shown to perform ideally when jammers are confined to a narrow angular distribution. Conversely, its performance deteriorates when jammers are distributed around the CRPA. Additionally, the presentation evaluates the effectiveness of various anti-spoofing techniques against different spoofing attack vectors. Finally, the analysis highlights the significance of modeling beyond-line-of-sight jammer power. Given that high-power jammer signals can refract over terrain, relying solely on terrain masking models may lead to an overestimation of GNSS receiver performance in proximity to the Earth’s surface.

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