전파간섭 영향분석 및 검출 알고리즘 개발을 위한 위성항법 전파간섭 시뮬레이터 설계

Abstract

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2013. 2. 박찬국.Global Navigation Satellite System (GNSS) is an essential system for land, maritime, and air navigation. GNSS is also used as main source for time synchronization in financial transaction and electrical grid. In addition, location based service based on GNSS is commonly used for general population. GNSS-based applications are proliferating due to its accuracy, convenience and low cost. However, most people do not realize how vulnerable GNSS is and its vulnerability problem has not resolved even though dependency on GNSS is rapidly increasing. The motivation of this thesis is to find a possible solution for GNSS vulnerability, especially for aviation applications. A Ground Based Augmentation System (GBAS) is an enabling technology for aircrafts’ GNSS based precision approach by enhancing GNSS navigation performance. The GBAS is well designed to ensure navigation system’s accuracy, integrity, availability, and continuity in normal radio frequency environment. However, its use is limited when radio frequency interference (RFI) is present. Some of potential RFI sources can be mitigated or eliminated by controlling unintentional RFI sources around airport and by enforcing law to prevent sales and use of commercial privacy jammers. However, RFI detection, mitigation and characterization system is still required for contingency. In this thesis, research is carried out to examine interference detection parameters and to propose applicable detection algorithm for aviation application. After analyzing pre-correlation and post-correlation detection parameters’ characteristics, an interference detection algorithm is developed utilizing AGC gain and adaptive lattice IIR notch filter parameters considering these parameter’s strengths and weaknesses. The proposed interference detection and characterization algorithm is designed to be used even in excessive RFI environment which prevent GNSS signal acquisition and tracking. The proposed algorithm can detect and classify various interference signals and estimate their signal power. The performance of the algorithm was verified by Monte-Carlo simulation. In addition, MATLAB SIMULINK GNSS interference simulator was designed to assess interference impact on GNSS receiver performance and to characterize interference detection parameters. The designed GNSS interference simulator is a flexible simulation platform to generate GNSS signal data in various types of interference environment according to users’ needs. Therefore, the GNSS interference simulator acted as an essential tool for interference detection and characterization algorithm development. The proposed detection and characterization algorithm and the GNSS interference simulator will be used for interference mitigation and location algorithm research.Chapter 1.Introduction 1 1.1 Motivation and Background 1 1.2 Objectives and Contributions 3 1.3 Organization 3 Chapter 2. Ground Based Augmentation System 4 2.1 Introduction 4 2.2 GBAS Requirement 5 2.3 GBAS Integrity Monitoring System 8 2.4 GBAS Stability Test Results and Recommendations 10 Chapter 3. GNSS Radio Frequency Interference 13 3.1 Types of RF Interference 13 3.2 Personal Privacy Devices 15 3.3 Intentional Jamming 18 Chapter 4. Interference Detection Parameter Analysis 19 4.1 Introduction 19 4.2 AGC Gain 20 4.3 ADC Histogram Distribution 20 4.4 Adaptive Notch Filter Parameters 21 4.5 Frequency Domain Approach 21 4.6 Carrier-to-Noise Ratio 22 4.7 Summary 23 Chapter 5. RFI Detection and Characterization Algorithm Design 25 5.1 RFI Detection Parameter Selection for GBAS 25 5.2 AGC Gain 25 5.2.1 AGC Model 25 5.2.2 AGC Characterization 27 5.3 Adaptive Lattice IIR Notch Filter Parameters 29 5.3.1 Adaptive Lattice IIR Notch Filter 29 5.3.2 Interference Detection and Classification using Adaptive Lattic IIR Notch Filter Parameters 32 5.4 Interference Detection and Characterization Algorithm 33 5.5 Performance Evaluation of the Proposed Algorithm 34 Chapter 6. Simulator Design for RFI Impact Assessment on GNSS 37 6.1 Introduction 37 6.2 GNSS Interference Signal Model 38 6.3 GNSS Interference Simulator Design 40 6.3.1 GPS Signal Generation Module 41 6.3.2 Interference Signal Generation Module 45 6.3.3 Front-end Signal Processing Module 48 6.4 RF Interference Impact Assessment 49 Chapter 7. Conclusions 54 Bibliography 56 국문초록 60Maste