Seongkyun Jeong

Implementation and test of GNSS spoofing detection module

As the field of GNSS application is stretched, the stability of GNSS is concerned. GNSS is connected with the social infrastructure and economic problem. GNSS is used in communication system, military weapon, power station, satellite system, and so on. The information of position and time which is provided by GNSS is related with economy and military capabilities. Thus the threat of GNSS attack will increase in the future. For dealing with this request, ETRI is developing GNSS interference detection system. In this paper, we introduce the GNSS interference detection system and specially focus on the spoofing detection module. The algorithm for detecting the spoofing signal is implemented on the GNSS interference detection system. The result of implemented system is verified by the system test. The functions of spoofing detection module are verified by the spoofing environment which is generated by test-bed.

Spoofing detection test of GPS signal interference mitigation equipment

Global Navigation Satellite System(GNSS) is vulnerable against the interference signal because the navigation signal is very weak on the ground. If the interference signal is induced on a GNSS receiver, the GNSS receiver will malfunction by the interference signal. In the point of national infrastructure, the protection of the GNSS signal becomes more important. For preventing the interference effects, Electronics and Telecommunications Research Institute(ETRI) developed GPS signal interference mitigation equipment. In this paper, we introduce the process and result of spoofing detection test. The spoofing detection function is the part of GPS signal interference mitigation equipment.

Analysis of 3D GIS- Based GNSS Visibility at Urban Area

Visibility of the satellite navigation is related to a environmental condition of a receiver. Obstacles like buildings and trees in urban areas can block signals and have effects on accuracy and reliability of positioning. This paper presents a method of creating 3D analysis model of urban canyon of Seoul using three-Dimensional digital map. Analysis techniques of visible satellites with Ray-Polygon Collision Detection and validation of algorithm through field tests are discussed. We have compared and analyzed the visibility of GPS and Galileo with respect to separate and simultaneous tracking in view of DOP (Dilution of Precision) using the 3D GIS digital map.

CONCEPTUAL DESIGN OF MONITORING AND CONTROL SUBSYSTEM FOR GNSS GROUND STATION

The Global Navigation Satellite System (GNSS) becomes more important and is applied to various systems. Recently, the Galileo navigation system is being developed in Europe. Also, other countries like China, Japan and India are developing the global/regional navigation satellite system. As various global/regional navigation satellite systems are used, the navigation ground system gets more important for using the navigation system reasonably and efficiently. According to this trend, the technology of GNSS Ground Station (GGS) is developing in many fields. The one of purposes for this study is to develop the high precision receiver for GNSS sensor station and to provide ground infrastructure for better performance services on navigation system. In this study, we consider the configuration of GNSS Ground Station and analyze function of Monitoring and Control subsystem which is a part of GNSS Ground Station. We propose Monitoring and Control subsystem which contains the navigation software for GNSS Ground System to monitor and control equipments in GNSS Ground Station, to spread the applied field of navigation system, and to provide improved navigation information to user.

New Method for GEO Station Keeping Using Hybrid Propagator and Optimization Technique

In this paper, a method of station keeping strategy using relative orbital motion and numerical optimization technique is presented for geostationary spacecraft. Relative position vector with respect to an ideal geostationary orbit is generated using high precision orbit propagation, and compressed in terms of polynomial and trigonometric function. Then this relative orbit model is combined with optimization scheme to propose a very efficient and flexible method of station keeping planning. Proper selection of objective and constraint functions for optimization can yield a variety of station keeping methods improved over the classical ones. Nonlinear simulation results have been shown to support such concept.

GNSS Interference Signal Generation scenario for GNSS Interference Verification Platform

GNSS(Global Navigation Satellite System) is used in various fields. Because the strength of GNSS signal is very weak on Earth surface, GNSS signal is easy to be disturbed by interference. For increasing the GNSS signal stability and availability, various mitigation methods and analysis of interference are studied. As these situation, it is necessary the standard platform to assist the interference mitigation studies and analyze receiver properties and interference effect. ETRI(Electronics and Telecommunications Research Institute) is developing GNSS Interference Signal Verification Platform. This platform generates interference signal and measures the receiver properties influenced by interference. Using the measurement result and signal propagation model, this platform analyzes the effect of interference. GNSS Interference Signal Verification Platform consists of GNSS Interference Signal Generation Equipment, GNSS Interference Signal Measurement Equipment, and GNSS Interference Propagation Model. This paper introduces GNSS Interference Signal Verification and describes the generation signal types which are jamming and spoofing interference. Finally we make the interference signal generation scenario for GNSS Interference Signal Generation Equipment. This scenario reflects the purpose and usage of GNSS Interference Signal Verification Platform.

Development of the Satellite Ground Control System for Multi-mission Geostationary Satellite COMS

A multi-mission GEO satellite, COMS has three payloads including Ka-band communications, GOCI, and MI. COMS SGCS is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS performs the following functions such as reception and processing of telemetry data via S-band link, planning and transmission of telecommand, tracking and ranging of the satellite, control and monitoring of SGCS equipment, analysis and simulation of the satellite, processing and analysis of flight dynamics data, and mission scheduling and reporting. By the proper functional allocations, COMS SGCS is divided into five subsystems such as TTC, ROS, MPS, FDS, and CSS. COMS SGCS is linked with MSC, KOSC, and IDACS for satellite related data exchange. The software in the COMS SGCS is designed using the object-oriented methodology and implemented using Microsoft C# .NET environment on Intel microprocessor based computers. The hardware in the COMS SGCS includes 13-m S-band mono-pulse Cassegrain antenna and RF/BB equipment. In this paper, development of the COMS SGCS is described with respect to system functional allocations, software and hardware design, system implementation, and system test.

Preliminary Design of Monitoring and Control Subsystem for GNSS Ground Station

GNSS (Global Navigation Satellite System) Ground Station monitors navigation satellite signal, analyzes navigation result, and uploads correction information to satellite. GNSS Ground Station is considered as a main object for constructing GNSS infra-structure and applied in various fields. ETRI (Electronics and Telecommunications Research Institute) is developing Monitoring and Control subsystem, which is subsystem of GNSS Ground Station. Monitoring and Control subsystem acquires GPS and Galileo satellite signal and provides signal monitoring data to GNSS control center. In this paper, the configurations of GNSS Ground Station and Monitoring and Control subsystem are introduced and the preliminary design of Monitoring and Control subsystem is performed. Monitoring and Control subsystem consists of data acquisition module, data formatting and archiving module, data error correction module, navigation solution determination module, independent quality monitoring module, and system operation and maintenance module. The design process uses UML (Unified Modeling Language) method which is a standard for developing software and consists of use-case modeling, domain design, software structure design, and user interface structure design. The preliminary design of Monitoring and Control subsystem enhances operation capability of GNSS Ground Station and is used as basic material for detail design of Monitoring and Control subsystem.

Generalized Satellite Multi-Body Attitude Dynamics Modeling using Component-based Design Methodology

The modeling of satellite multi-body dynamic is quite complicate process. In developing satellite simulator, it’s proper to use multi-body dynamics in modeling satellite attitude dynamics. We will introduce the attitude dynamic module that is able to cover various satellites and operational phases. This approach may improve portability of satellite modeling. The generalization of multi-body attitude dynamics model can be used to analyze orbit and attitude dynamic of satellite. It is very useful for various satellites system and applying to other system with several parameters change.

Fault Management System Using Penalty Method and Data Buffer for Communication Satellite

Satellite system has lots of fault causes. For some communications satellite systems, fault management and data preservation are required to exchange data continuously and provide broadcasting service. In this paper, we have proposed fault management of satellite system using penalty method, data buffer and recovery manager. The penalty manager imposes penalty according to fault degree and manages fault quantitatively. Data Buffer has the function to store data in fault situation and prevent data damage. Recovery manager performs system monitoring and to operates recovery process in fault situation. Proposed method is fundamental concept of the architectural characteristics and enhances satellite fault management performance. This capability permits the satellite to detect and correct some of its own failures autonomously. Also, the effect of penalty method and data buffer on fault management design has been discussed.