Triple-Satellite Geolocation from Low Earth Orbit in a Multi-Emitter GNSS Interference Environment
A Parametric System Analysis
J.L.F. Raithel (TU Delft - Aerospace Engineering)
E.J.O. Schrama – Mentor (TU Delft - Aerospace Engineering)
D. Dirkx – Graduation committee member (TU Delft - Aerospace Engineering)
M.J. Heiligers – Graduation committee member (TU Delft - Aerospace Engineering)
Maarten Menken – Mentor (Royal Netherlands Aerospace Centre)
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Abstract
GNSS jammers can disrupt critical positioning, navigation, and timing services. Low Earth orbit satellites offer a way to locate these emitters over large areas. This thesis studies passive geolocation of stationary terrestrial GNSS jammers with a three-satellite LEO system.
Two geolocation approaches are compared. The first estimates emitter positions directly from received I/Q data. The second first extracts receiver-differenced observables and then estimates position from FDOA measurements. These approaches are referred to as direct and indirect geolocation. A parametric simulation framework is developed to model the satellite formation, jammer signals, receiver data, and main error sources. A CRLB analysis is used to study the design space.
The results show that both approaches can achieve sub-kilometer per-emitter accuracy. In Scenario 1, the direct method reaches a mean error of 502m, while the indirect method reaches 143m. In Scenario 2, the corresponding values are 517m and 292m. The indirect method also provides precision estimates through 95\% confidence ellipses. Its main advantage is computational cost. It is about 900 times faster per snapshot in the reported implementation.
The results also show that a tight formation is preferred. It maximizes the shared field of view while keeping enough geometric diversity. The FDOA loop-closure constraint is found to be essential. It rejects false candidates and makes indirect geolocation practical in a multi-emitter setting.
This thesis concludes that FDOA-based indirect geolocation with a tight three-satellite LEO formation is the most suitable option for low-latency wide-area GNSS interference geolocation within the considered scope. Future work should validate the method with more scenarios or real satellite data.