• ETRI Journal
• /
• v.25 no.5
• /
• pp.387-400
• /
• 2003

Since its launching on 21 December 1999, the Korea Multi-Purpose Satellite-I (KOMPSAT-I) has been successfully operated by the Mission Control Element (MCE), which was developed by the ETRI. Most of the major functions of the MCE have been successfully demonstrated and verified during the three years of the mission life of the satellite. This paper presents the operational performances of the various functions in MAPS. We show the performance and analysis of orbit determinations using ground-based tracking data and GPS navigation solutions. We present four instances of the orbit maneuvers that guided the spacecraft form injection orbit into the nominal on-orbit. We include the ground-based attitude determination using telemetry data and the attitude maneuvers for imaging mission. The event prediction, mission scheduling, and command planning functions in MAPS subsequently generate the spacecraft mission operations and command plan. The fuel accounting and the realtime ground track display also support the spacecraft mission operations.

• Journal of Astronomy and Space Sciences
• /
• v.38 no.1
• /
• pp.45-53
• /
• 2021

GLONASS, a satellite navigation system developed in Russia since 1976, is defunct and orbits in an unstable attitude. The satellites in these problems are not managed and there is no precise information, which can increase the risk of collisions with other space objects. In this study, detailed attitude dynamic have to be analyzed through photometry data, which requires spin period and spin axis. The light curve data is obtained by observing through the photometer at the Graz station and the power spectrum is calculated to obtain the cycle of the satellite. The geometric relationship between observer and sun is analyzed for GLONASS-50 satellite. The box-wing model is applied to obtain the phase reflection of the satellite and obtain the Irradiation of the satellite through this information. In Light Curve and Irradiation, the spin axis is calculated for each peak points with the distance square minimum technique. The spin axis of the GLONASS-50 satellite is RA = 116°, Dec = 92°.

• Journal of the Korean Institute of Navigation
• /
• v.6 no.2
• /
• pp.13-33
• /
• 1982

The NAVSTAR/GPS is a satellite-based navigation system that will provide extremely accurate three-dimensional position and velocity information to users anywhere on or near the earth. This system has been studied primarly for military use and thus the results of studies are seldom obtainable for civilian use up to date. Expecting this system to be opened to civilian use in the future, this paper aims to the collection of basic data of the PN phase modulated communication system adopted in the GPS system by computer simulation. The results of studies are as follows; 1) The PN phase modulation of the speed of 106b/s can be simulated by Fourier summation, the spectrum region which can be restricted is in the region of 0.5-1.5 MHz and spectrum number required is over than 270. 2) By computer simulation, it is verified that optimum r.f filter bandwidth is about 0.3 MHz for the case of $10^6$b/s PN codes phase modulated in 1.575GHz carrier. 3) In case that PN rate to data rate is between 10 and 100, the allowable minimum SNR to demodulate data signal correctly by optimum LPF is about 0.3. It is also verified that the larger the frequency ratio of PN code to the data code, the lower the allowable minimum SNR required.

• Journal of Advanced Navigation Technology
• /
• v.12 no.4
• /
• pp.295-303
• /
• 2008

Malfunction of satellite launch vehicles with high speed and long range can be a major concern for operations. Flight safety system that monitor the trajectory and identify any failure of the launch vehicles. Tracking filters for the flight safety systems are different from common tracking filters since filter reliability is more emphasized than accuracy. Reliable estimation of instantaneous impact points requires reliable velocity estimates as well as reliable position estimates. A fusion filter for a flight safety system was developed with the tracking sensor models for the Korea Satellite Launch Vehicle I. The fusion filter performances were evaluated by analyzing the trajectory and instantaneous impact point estimates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.297-300
• /
• 2016

The typical Differential Global Navigation Satellite System service of South Korea is the Ground Based Differential GNSS service. South Korea building the Satellite-Based Augmentation System for GNSS to expand the Differential GNSS service. The satellite-based differential GNSS serive is called the SBAS(Satellite Based Augmentation System). The SBAS reference station on ground should be installed to operate the SBAS service alike the ground based augmentation system. That SBAS reference station can be installed with ground based DGNSS reference station. To make the SBAS reference station combined with the ground based DGNSS reference station, DGNSS system should be connected to NovAtel's G-III receiver. In this paper, the DGNSS software reference station's software module architecture was changed and G-III interface module was designed to use the G-III receiver.

• Journal of Advanced Navigation Technology
• /
• v.24 no.1
• /
• pp.16-27
• /
• 2020

This paper investigates the applicability of optical flow information for unmanned aerial vehicle (UAV) navigation under environments where global navigation satellite system (GNSS) is unavailable. Since the optical flow information is one of important measurements to estimate horizontal velocity and position, accuracy of the optical flow information must be guaranteed. So a navigation algorithm, which can estimate and cancel biases that the optical flow information may have, is suggested to improve the estimation performance. In order to apply and verify the proposed algorithm, an integrated simulation environment is built by designing a guidance, navigation, and control (GNC) system. Numerical simulations are implemented to analyze the navigation performance using this environment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.3-8
• /
• 2006

The next decade promises drastic improvements and additions to global navigation satellite systems (GNSS). Plans for GPS modernization include a civilian code measurement on the L2 frequency and a new L5 signal at 1176.45 MHz. Current speculations indicate that a fully operational constellation with these improvements could be available by 2013. Simultaneously, the Galileo Joint Undertaking is in the development and validation stages of introducing a parallel GNSS called Galileo. Galileo will also transmit freely available satellite navigation signals on three frequencies and is scheduled to be fully operational as early as 2008. In other words, a dual system receiver (e.g., GPS+GALILEO) for general users can access six civil frequencies transmitted by at least fifty eights navigation satellites in space. The advent of GALILEO and the modernization of GPS raise a lot of attention to the study of the compatibility and interoperability of the two systems. A number of performance analyses have been conducted in a global scale with respect to availability, reliability, accuracy and integrity in different simulated scenarios (such as open sky and urban canyons) for the two systems individually and when integrated. Therefore, the scope of this article aims at providing the technical benefits analysis for Taiwan specifically in terms of the performance indices mentioned above in a local scale, especially in typical urban canyon scenarios. The conclusions gained by this study will be applied by the Land Survey Bureau of Taiwanese as the guideline for developing future GNSS tracking facilities and dual GNSS processing module for precise surveying applications in static and kinematic modes.

• Journal of Navigation and Port Research
• /
• v.31 no.8
• /
• pp.645-652
• /
• 2007

As a method to improve the present operational and safe function in navigation this paper developed an efficient and economical integrated system of ship's information. This system is, systematically and comprehensively, to monitor, save, analyse, and display information on navigation and environment around own ship in real time by connecting one user to another through an on-board LAN or data communication via satellite so that many users on board can obtain simultaneously and easily the information in real time not only in the wheelhouse and engine room but also in many robins and ship's offices. And it consists of four(5) components; data distribution program, database of navigational and engine-related information, multi-functional monitoring program, ship management program and other application program.

• Journal of the Korean Professional Engineers Association
• /
• v.41 no.5
• /
• pp.55-58
• /
• 2008

GPS is the global Navigation Satellite System which is developed by the United States Department of Defense as an abbreviation of the Global Positioning System. The GPS uses a constellation of 24 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their location, speed, direction, and time. Following, the shooting down of Korean Air Lines Flight 007 in 1983. President Ronald Reagan issued a directive making the system available free for civilian use as a common good. Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, and hobbies such as geocaching. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

• Journal of the Korean Institute of Navigation
• /
• v.22 no.2
• /
• pp.1-12
• /
• 1998

The fundamental objectives of vessel traffic services (VTS) are the safety of traffic, efficient traffic flow and the protection of marine environment. And the coverge of VTS is used to be within the port and their approaches. It , however, is tend to expand the coverge beyond the radar coverage and the vessel carrying dangerous cargo. Therefore this study aims to investigate the international tendancy of the extended VTS system, and take a field test of using KOREASAT for the extended VTS system in Korean coastal waters. As the results of the test, KOREASAT is proved to be one of the alternatives for extended VTS system.