Nghiên cứu giải pháp nâng cao khả năng chống nhiễu cho các bộ thu định vị GNSS tiên tiến

s MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY NGUYEN DINH THUAN ROBUST SIGNAL PROCESSING TECHNIQUES FOR MODERN GNSS RECEIVERS Major: Computer Engineering Code No.: 9480106 COMPUTER ENGINEERING DISSERTATION SUPERVISORS: Assoc Prof Ta Hai Tung Prof Letizia Lo Presti Hanoi - 2019 STATEMENT OF ORIGINALITY AND AUTHENTICITY I confirm that my dissertation is an original and authentic piece of work written by myself The data, results in the thesis is reliable and has never been published by others I further confirm that I have fully referenced and acknowledged all material incorporated as secondary resources in accordance with the regulations Hanoi, SUPERVISORS PHD STUDENT PGS.TS Tạ Hải Tùng Nguyễn Đình Thuận Prof Letizia Lo Presti ACKNOWLEDGEMENTS I would like to express my gratitude to Hanoi University of Technology, Graduate School, School of Information and Communication Technology, Department of Computer Engineering and Politecnico di Torino, NavSaS group for creating favorable conditions for me to work and study I would like to express my special thanks to my supervisors, Assoc Ta Hai Tung and Prof Letizia Lo Presti The supervisors have always been helpful, giving great advice, scientific orientations so that I can develop and complete my research Sincerely thank the lecturers, colleagues in the Department of Computer Engineering, School of Information and Communication Technology, Hanoi University of Science and Technology where I work, study and carry out research projects for the enthusiastic in helping and encouraging me during the research With gratitude to teachers, scientists, colleagues and close friends for encouraging and supporting me in the research process Finally, I would like to express my deep gratitude to my family for encouraging me to overcome all obstacles to complete this thesis Nguyen Dinh Thuan TABLE OF CONTENTS STATEMENT OF ORIGINALITY AND AUTHENTICITY ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF ACRONYMS LIST OF TABLES LIST OF NOTATIONS IN THIS THESIS ……………………………………….…9 LIST OF FIGURES 10 INTRODUCTION 13 FUNDAMENTAL BACKGROUND 18 1.1 GNSS positioning principle 18 1.2 History and development of GNSS 19 1.3 GNSS Threats 20 1.3.1 Multipath 21 1.3.2 Atmosphere 21 1.3.3 Interference 21 1.3.4 Spoofing 21 1.3.5 GNSS Segment errors 21 1.3.6 Cyber Attacks 22 1.4 1.4.1 Signal Conditioning and Sampling 22 1.4.2 Acquisition 23 1.4.3 Tracking and Data Demodulation 23 1.4.4 Positioning Computation 24 1.5 Countermeasures to GNSS Threats 25 1.5.1 Antenna array processing techniques 25 1.5.2 Frontend and Digital Signal Conditioning based techniques 28 1.5.3 Correlator/Tracking and PVT based techniques 29 1.6 GNSS Receiver Architecture 22 GNSS Simulator and effect of sampling frequency 30 ANTENNA ARRAY PROCESSINGS FOR GNSS RECEIVERS 33 2.1 2.1.1 Determining the samples difference 34 2.1.2 Determining the clock phase shift 35 2.2 Implementation a low-cost antenna array 39 2.3 Antenna array frontend verification 40 2.3.1 Phase difference between frontends 40 2.3.2 Carrier to noise ration improvement 41 2.4 The proposed solution for synchronizing separated antenna array element 33 Conclusion 42 GNSS SNAPSHOT PROCESSING TECHNIQUE FOR GNSS RECEIVERS 44 3.1 Proposed Design of GNSS Snapshot Receiver 44 3.1.1 GNSS Grabber 44 Implementation of GNSS Grabber 44 Firmware Architecture 45 3.2 3.2.1 GNSS signal acquisition 45 3.2.2 Combined Doppler and Snapshot Algorithm 48 3.3 Loosely coupled Snapshot GNSS/INS 53 3.4 Tightly coupled Snapshot GNSS/INS 60 3.5 Results 61 3.5.1 Standalone Snapshot GNSS Receiver 61 3.5.2 Snapshot GNSS/INS Integration 66 3.6 Server Software 45 Conclusion 68 GNSS SIGNAL SIMULATOR DESIGN AND IMPLEMENTATION 69 4.1 Modeling methodology 69 4.2 Overview of the modeling of antenna array signals in GNSS receivers 69 4.2.1 General model of the received signal in GNSS receivers 70 4.2.2 Interference 74 4.2.3 Multipath 75 4.2.4 Noise 76 4.3 Effect of sampling frequency and mitigation technique 76 4.3.1 Effect of sampling frequency on positioning performance 76 4.3.2 Implementation of sampling mitigation technique for GNSS Simulator 79 4.4 Performance verification 81 4.4.1 Verification of the simulated antenna array signals 81 4.4.2 Antenna distortion simulation 87 4.4.3 Verification of multipath simulation 89 4.5 Conclusion 90 CONCLUSIONS AND FUTURE WORKS 92 PUBLICATIONS 94 REFERENCES 96 LIST OF ACRONYMS Acronym Meaning ADC Analog to Digital Converter AGC Automatic Gain Control AWGN Additive White Gaussian Noise BB BaseBand BOC Binary Offset Carrier BPSK Binary Phase Shift Keying C/A Coarse/Acquisition C/N0 Carrier-to-Noise-Density Ratio CDC Conventional Differential Combination CDMA Code Division Multiple Access CRC Cyclic Redundancy Check CS Commercial Service DLL Delay Lock Loop DFT Discrete Fourier Transform DSP Digital Signal Processor EGNOS European Geostationary Navigation Overlay Service EU European Union FEC Forward Error Correction FFT Fast Fourier Transform FPGA Field Programmable Gate Array FOC Full Operational Capability GLONASS Global Orbiting Navigation Satellite System I Inphase IF Intermediate Frequency Q Quadrature PVT Position Velocity Time SDR Software Defined Radio LIST OF TABLES Table 3.1: Configuration of the GPS grabber 61 Table 3.2: Information of acquired satellites 63 Table 4.1: GNSS Simulator Features 81 Table 4.2: The coordinate of elements 82 Table 4.3: The direction of visible satellites 82 Table 4.4: The carrier phase relative to the first element of each satellite at the four elements of the array 83 Table 4.5: The simulation scenario 83 Table 4.6: Estimated carrier phase using the post-correlator beamforming tracking loop 86 LIST OF NOTATIONS IN THIS THESIS Notation Description 𝜏 Code phase 𝜌 Pseudo range Φ Carrier Phase 𝐶(𝑡) Spreading Code exp(𝑗2𝜋𝑓𝑡) Complex expression of in-phase and quadrature carrier component 𝐹𝑠 Sampling Frequency 𝐹𝐼𝐹 Intermediate Frequency 𝐷(𝜏) Discrimination Function 𝑐 Speed of light 𝐼(𝑡) In-phase tracking output 𝑄(𝑡) Quadrature tracking output E, L, P Early, Late, and Prompt branch of tracking stage 𝒘 Weight vector 𝑅 Cross correlation 𝜑 Latitude 𝜆 Longitude ℎ Height 𝑣 Velocity 𝑅𝑀 The radius of curvature 𝑅𝑁 The prime vertical radius ... 42 GNSS SNAPSHOT PROCESSING TECHNIQUE FOR GNSS RECEIVERS 44 3.1 Proposed Design of GNSS Snapshot Receiver 44 3.1.1 GNSS Grabber 44 Implementation of GNSS Grabber... the processing chains in GNSS receivers are fully described 1.1 GNSS positioning principle This section will explain the general principle of GNSS navigation Basically, GNSS positioning is based... [1] Thuan Nguyen Dinh, Ta Hai Tung, and Lo Presti Letizia (2015) "A software based multi-IF output simulator." Proceedings of the International Symposium of GNSS (ISGNSS), Kyoto, Japan 2015 (Scholarship