Ovrednotenje načinov motenja globalnega sistema pozicioniranja

Dolinšek, Staš (author), Batagelj, Boštjan (mentor), Blatnik, Aljaž (co-mentor)

V tem diplomskem delu raziskujem teorijo delovanja globalnega sistema za določanje položaja (angl. global positioning system – GPS), načrtovanje meritev motenja signala GPS, metode obdelave podatkov, pridobljenih s sprejemnikom in motilnikom ter analizo in vrednotenje različnih tehnik motenja signala GPS. Delo se začne z opisom teorije razširjenega spektra in njegove uporabe v kontekstu signala GPS, saj je ta tehnika ključna tako za zmanjšanje motenj kot tudi za določanje lokacije sprejemnika. Predstavljen je vpliv ozkopasovne motnje na vrednosti razmerja moči nosilnika proti šumu (angl. carrier to noise ratio – C/N) posameznih satelitov, kasneje pa tudi komentiran graf proizvajalca uporabljenega GPS modula, U-blox, v katerem je prikazana krivulja slabljenja signala v odvisnosti od moči in frekvence motnje. Opisane so tudi specifikacije modula Neo-6m ter analogne in digitalne tehnike, ki se uporabljajo za odpravo vpliva motenj. Naslednji del dela opisuje priprave na izvedbo meritev. Predstavljena so sporočila standardiziranega podatkovnega formata nacionalnega združenja pomorske elektronike (angl. National Marine Electronics Association – NMEA), iz katerih pridobivam potrebne podatke za določanje kakovosti sprejema signala GPS, ter nato pisanje programa v programskem jeziku Python, s katerim sem uredil vse sprejete informacije in jih uredil v grafe. Ti prikazujejo C/N vrednosti posameznega satelita, uporabo satelitov za izračun lokacije, vrednosti horizontalne napake določanja položaja (angl. horizontal dilution of precision – HDOP) in zmožnost določanja lokacije v odvisnosti od moči in frekvence motilnika. Zadnji del se osredotoča na praktično delo, v katerem sem najprej izmeril signal GPS s pomočjo spektralnega analizatorja, nato pa ojačenje predojačevalnika v uporabljeni anteni. Sledile so osnovne meritve, pri katerih sem z visokofrekvenčnim virom, preko smernega sklopnika, neposredno v modul GPS vnašal motilni signal. Izvedel sem 20 meritev, med katerimi sem spreminjal parametre in uporabljal različne tehnike motenja. S tem sem pridobival podatke o kakovosti sprejema, ki sem jih nato s pomočjo razvitega programa oblikoval v končne rezultate meritev. Končni rezultati so učinkovito pokazali sposobnost primerjave in analize različnih tehnik motenja, validacijo uspešnosti motenja ter jasno predstavitev zbranih podatkov.

• Language: Slovenian
• Keywords: GPS motilec, meritve, programiranje, DNSS, smerni sklopnik, frekvenčno skakanje, predojačevalnik, frekvenčni spekter, NMEA sporočila, SNR
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2023
• PID: 20.500.12556/RUL-148927
• COBISS.SI-ID: 163334915
• Publication date in RUL: 01.09.2023

Secondary language

• Language: English
• Title: Evaluation of Global Positioning System jamming methods

Abstract

In this thesis, I explore the theory of global positioning system (GPS) operation, the design of GPS signal jamming measurements, methods of processing the data obtained from the receiver and jammer, and the analysis and evaluation of different GPS signal jamming techniques. The work begins with a description of the theory of the spread spectrum and its use in the context of the GPS signal, as this technique is crucial for both reducing interference and determining the location of the receiver. The influence of narrowband interference on the carrier-to-noise ratio (C/N) values of individual satellites is presented, followed by a commentary on a graph provided by the manufacturer of the GPS module used, U-blox, which shows the attenuation curve of the signal as a function of the power and frequency of the interference. Specifications of the Neo-6m module are described and both analog and digital techniques used to mitigate the impact of interference are presented. The next part of the work describes the preparations for conducting the measurements. A standard data format of National Marine Electronics Association (NMEA) messages is presented, from which I obtained the necessary data to determine the quality of GPS signal reception, followed by writing a program in the Python programming language that organized all the received information and converted it into graphs. These graphs show the C/N values of individual satellite, the use of the satellites for location calculation, the HDOP values, and the ability to determine location depending on the power and frequency of the jammer. The last part focuses on the practical work, in which I first measured the GPS signal using a spectrum analyzer and then measured the gain of the preamplifier in the antenna used. This was followed by basic measurements where, using a high-frequency source, I directly injected the jamming signal into the GPS module through a directional coupler. I conducted 20 measurements, during which I varied parameters and used different jamming techniques. With these, I obtained data on reception quality, which I then transformed into final measurement results using the developed program. The final results effectively demonstrated the ability to compare and analyze different jamming techniques, validate the success of the jamming, and clearly present the collected data.

• Keywords: GPS jammer, measurements, programming, DNSS, directional switch, frequency hopping, pre-amplifier, frequency spectrum, NMEA messages, SNR