JR
J.L.F. Raithel
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Triple-Satellite Geolocation from Low Earth Orbit in a Multi-Emitter GNSS Interference Environment
A Parametric System Analysis
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. ...
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. ...
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.
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.