Risk assessment of electromagnetic interference in aerospace systems
This thesis investigates statistical techniques for processing the measured electromagnetic emissions in the time-domain to analyze the risk of electromagnetic interference using the amplitude probability distribution (APD) as the main indicator. The APD allows determining the probability that a sig...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/441641 |
| Acceso en línea: | https://hdl.handle.net/2117/441641 |
| Access Level: | acceso embargado |
| Palabra clave: | Electromagnetic interference Radio frequency Electromagnetic compatibility Amplitude Probability Distribution Risk Assessment Jammers GNSS RAMS Electromagnetic Compatibility EMC EMI Areoespace Systems Metrology Interferència electromagnètica Radiofreqüència Compatibilitat electromagnètica Àrees temàtiques de la UPC::Aeronàutica i espai |
| Sumario: | This thesis investigates statistical techniques for processing the measured electromagnetic emissions in the time-domain to analyze the risk of electromagnetic interference using the amplitude probability distribution (APD) as the main indicator. The APD allows determining the probability that a signal exceeds a certain amplitude threshold within a given frequency range. One of the main challenges in applying APD is the lack of standardized calibration procedures, which compromises the metrological traceability of the tests. To address this, two complementary calibration methods are proposed: one based on deterministic signals and the other on pseudo-random signals with known statistical properties. The first method uses pulsed and continuous wave signals to evaluate measurement errors at specific probability and amplitude levels, while the second employs Gaussian white noise and Gaussian mixture models to analyze the statistical parameters of the distribution. The calibration validation demonstrates that both methods enable verification that the APD function complies with the tolerances established by CISPR 16-1-1, providing a reliable and traceable procedure for its calibration. To apply APD to emission risk analysis, a procedure has been developed to evaluate the probability of exceeding amplitude levels across a wide frequency range. A spectrum-type graphical representation has been designed, where probabilities are displayed using color gradients or categories, making it easier to identify regions with the highest impact of electromagnetic interferences. These regions are defined according to emission limits and immunity levels established by electromagnetic compatibility standards, setting acceptable probability ranges for each impact level. The procedure was validated by assessing the risks of three low-cost, illegally marketed GNSS jammers with different morphologies. The devices were characterized in terms of power, spectrum, spectrogram, and probability distribution using measurements in both the time and frequency domains, and their potential effective range was estimated. Furthermore, both methodologies were compared, showing that time-domain measurements provide a more detailed view of the behavior and influence of interferences. The results show that these jammers use chirp signals or modulated wideband noise to disrupt pseudo-range acquisition, corrupt satellite data, mask signals, or saturate GNSS receivers in the L1, E1, B1, and G1 bands. Regarding risk analysis, the wideband APD measurement provides additional information about the impact of interferences and allows determining the risks posed by jammers in devices compliant with the MIL-STD-461G standard. The results indicate that jammers designed to affect GNSS signals produce a medium impact on aerospace systems, whereas those intended for cellular communications have a low effect on the GNSS band. In conclusion, APD measurement has proven to be effective for evaluating emission risks, providing more detailed insights into the behavior of interferences and establishing a simple and intuitive framework for interpreting results through its wideband spectral representation. |
|---|