• Title/Summary/Keyword: Global Navigation Satellite System (GNSS)

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Reduced Order Luenberger State Observer Design for Lateral Direction Approach Control of Aircraft (항공기의 횡방향 접근 제어를 위한 축소차수 상태관측기 설계)

  • Lee, Byung-Seok;Heo, Moon-Beom;Nam, Gi-Wook;Park, Hyeong-Taek
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.2
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    • pp.18-25
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    • 2012
  • The availability of the GPS signal has been expanded greatly in the field of society overall through the development and construction of the GNSS(Global Navigation Satellite System). Furthermore, in the military, aviation and field of space, the GPS signal is applied widely through the combination of INS consisting of gyroscope and accelerometer, IMU, AHRS with the addition of magnetic sensor. Particularly, the performance of these equipments or sensors is very important with GPS and PAR(Precision Approach Radar) in the flight control of the aircraft. This paper deals with MATLAB simulation and ROLSO(Reduced Order Luenberger State Observer) design to reduce the load of system and realize the stable lateral direction approach control in an appropriate time for reduction of the horizontal error which is importantly considered while an aircraft lands instead of the FOLSO(Full Order Luenberger State Observer) using all measurement values. Consequently, ROLSO is expected to be used for the aircraft's attitude control in the aircraft landing causing the burden to the pilots.

Preliminary Results of Surveillance Data Processing for Design of Prototype ADS-B/TIS-B Validation Testbed (연구용 ADS-B/TIS-B Validation Testbed 설계를 위한 항공감시데이터 처리의 예비 결과)

  • Song, Jae-Hoon;Oh, Kyung-Ryoon;Kim, In-Kyu;Lee, Jang-Yeon
    • Journal of Advanced Navigation Technology
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    • v.12 no.6
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    • pp.539-547
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    • 2008
  • In this paper, preliminary results for design of prototype ADS-ADS-B/TIS-B Validation Testbed (AVT) are described. Automatic Dependent Surveillance (ADS-B) is a novel surveillance concept using the Global Navigation Satellite System (GNSS) and a digital datalink. Air traffic information from ADS-B non-equipped aircraft is not acquired since ADS-B is a dependent surveillance. Traffic Information Service-Broadcast (TIS-B) provides surveillance data from Secondary surveillance Radar (SSR) for ADS-B non-equipped aircraft. AVT is based on ADS-B and TIS-B as an integrated platform for air traffic surveillance system for CNS/ATM.

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Current state and future prospect of technology development in satellite application (인공위성 활용 분야 기술 발전 현황 및 전망)

  • Lee, Jeong-Ho;Yoon, Bo-Yeol;Kim, Youn-Soo;Lim, Deok-Won;Heo, Moon-Beom;Lee, Byoung-Sun;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.8
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    • pp.728-740
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    • 2016
  • Korea developed several satellites through government-led satellite development projects, and now operates earth observation satellites of various sensors, science and technology satellites, and communication satellites. Satellites can be utilized in many fields, and Satellite Information, Global Navigation Satellite System, Satellite Communications and Broadcasting, Space Solar Power System are typical application fields. Now that we have developed and operated several satellites, we have to concentrate more efforts on satellite application. In this paper, we reviewed the current states of the technologies of four satellite application fields mentioned above and analyzed the future prospects of them.

Study on a Method for Performance Evaluation and Analysis of TWSTFT Modems (TWSTFT 모뎀의 성능평가방안 및 성능분석)

  • Juhyun Lee;Ju-Ik Oh;Joon Hyo Rhee;Gyeong Won Choi;Jong Koo Lee;Sung-hoon Yang;Youn-Jeong Heo;Dai-Hyuk Yu;Myoung-Sun Heo;Young Kyu Lee
    • Journal of Positioning, Navigation, and Timing
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    • v.13 no.3
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    • pp.355-363
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    • 2024
  • Time synchronization is crucial for ensuring the reliable operation of modern economic and social infrastructures. Techniques such as Global Navigation Satellite System (GNSS)-based methods and Two-Way Satellite Time and Frequency Transfer (TWSTFT) play key roles in precise time comparison and synchronization. TWSTFT, in particular, is recognized for its ability to achieve sub-nanosecond accuracy in time transfer, making it indispensable in fields such as satellite navigation. This paper proposes a comprehensive performance evaluation method for TWSTFT modems, emphasizing pre-validation in controlled environments to mitigate operational challenges. Using the proposed evaluation method, the study presents the standard deviation of RTT according to C/N0 and compares it with the datasheet of a commercial TWSTFT modem. Through this approach, the aim of this study is to enhance the reliability and accuracy of TWSTFT-based time synchronization across diverse applications.

Analysis of Galileo GIOVE-A E1 Signal and RF Front-End Bandwidth Effects (갈릴레오 GIOVE-A E1 신호 분석 및 RF 프론트엔드 대역폭 영향 분석)

  • Lee, Byung-Hyun;Im, Sung-Hyuck;Jee, Gyu-In;Ko, Sun-Jun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.8
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    • pp.767-773
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    • 2008
  • Galileo is a new civil Global Navigation Satellite System(GNSS) developed by Europe. GIOVE-A, a satellite to test Galileo system performance, transmits navigation signal on orbit. Evaluation of Galileo system and development of Galileo receiver needs to analyze GIOVE-A signals. In this paper, we received GIOVE-A signals and processed it using GIOVE-A Interface Control Document(ICD). Signal acquisition, tracking and navigation message decoding made grasping current signal status possible. Bandwidth increase by BOC modulation is one of the difference from GPS. Therefore, we investigated feasibility of conventional GPS L1 RF front-end to receive GIOVE-A E1 signal by evaluation of receiving performance of navigation signal on each bandpass filter of RF front-end.

Performance of Interference Mitigation with Different Wavelets in Global Positioning Systems

  • Seo, Bo-Seok;Park, Kwi-Woo;Park, Chansik
    • Journal of Positioning, Navigation, and Timing
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    • v.8 no.4
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    • pp.165-173
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    • 2019
  • In this paper, we apply a discrete wavelet packet transform (DWPT) to reduce the influence of interference in global positioning system (GPS) signals and compare the interference mitigation performance of various wavelets. By applying DWPT to the received signal, we can gradually divide the received signal band into low-pass and high-pass bands. After calculating the average power for the separate bands, we can determine whether there is interference by comparing the value with the given threshold. For a band that includes interference, we can reconstruct the whole band signal using inverse DWPT (IDWPT) after applying a nulling method that sets all of the wavelet coefficients to 0. The reconstructed signals are correlated with the pseudorandom noise (PRN) codes to acquire GPS signals. The performance evaluation is based on the number of satellite signals whose peak ratio (defined as the ratio of the first and second correlation peak values in the acquisition stage) exceeds the threshold. In this paper, we compare and evaluate the performance of 6 wavelets including Haar, Daubechies, Symlets, Coiflets, Biorthogonal Splines, and Discrete Meyer.

An Unambiguous Multipath Error Mitigation Scheme for TMBOC and CBOC Signals (TMBOC과 CBOC 신호에 적합한 모호성이 낮은 다중경로 오차완화 기법)

  • Yoo, Seung-Soo;Jee, Gyu-In;Kim, Sun-Yong
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.10
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    • pp.977-987
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    • 2012
  • One of the most significant errors in the pseudo-range measurement performance of GNSSes (Global Navigation Satellite Systems) is their multipath error for high-precision applications. Several schemes to mitigate this error have been studied. Most of them, however, have been focused on the GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal that was designed in the 1970s and is still being used for civil navigation. Recently, several modernized signals that were especially conceived to more significantly mitigate multipath errors have been introduced, such as Time Multiplexed and Composite Binary Offset Carrier (TMBOC and CBOC, respectively) signals. Despite this advantage, however, a problem remains with the use of TMBOC and CBOC modulations: the ambiguity of BOC (Binary Offset Carrier)-modulated signal tracking. In this paper, a novel unambiguous multipath error mitigation scheme for these modernized signals is proposed. The proposed scheme has the same complexity as HRCs (High Resolution Correlators) but with low ambiguity. The simulation results showed that the proposed scheme outperformed or performed at par with the HRC in terms of their multipath error envelopes and running averages in the static and statistical channel models. The ranging error derived by the mean multipath error of the proposed scheme was below 1.8 meters in an urban area in the statistical channel model.

Performance Evaluation of Double-Differencing Position-Domain Hatch Filter By a Landing Experiment (착륙 실험에 의한 이중차분 위치영역 Hatch 필터의 성능 분석)

  • Kim, Hee-Sung;Joo, Jung-Min;Lee, Hyung-Keun
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.18 no.1
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    • pp.19-26
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    • 2010
  • To expand the application area of global navigation satellite systems, precision landing is one of the most critical area to be solved. For the development and validation of the precision landing system, many aspects need to be analyzed including the system architecture, signal characteristics, atmospheric delay, communication delay, accuracy, integrity, and availability. Among them, the signal characteristics analysis requires the processing of measurements collected by real-flight experiments. This paper presents the processing results of the real measurements collected by a flight and landing experiment. To process and analyze the data, double differencing position-domain hatch filter is utilized. Accuracy of the proposed filter is evaluated utilizing reference trajectory generated by commercial software. Finally, by comparing with conventional range domain characteristics of position domain filter is analyzed.

Development Activity Tracking System Using Accelerometer and Earth Magnetic Field Sensor (지자계 및 가속도 센서를 이용한 활동추적 시스템 개발)

  • Jung, Hwan;Kang, Hag-Seong;Jeong, Do-Un
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2010.05a
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    • pp.144-147
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    • 2010
  • 본 연구에서는 실내의 활동추적 시스템을 위해 가속도센서와 지자계 센서를 이용하여 외부로부터 독립적인 소형의 관성항법장치를 제안하였다. 기존의 실내 위치추적은 주로 GNSS(global navigation satellite system)의 정보를 가져와 실내 환경에 맞게 초음파와 RSSI(received signal strength indicator)등을 이용하여 구성한 경우가 연구되었으나 이러한 위성항법은 좌표 값이 미리 저장된 고정 노드가 필수적이라는 단점이 있다. 따라서 본 연구에서는 실내 환경과 같이 이동거리가 길지 않으며, 기존 환경 및 외부로부터의 영향에서 자유로운 관성항법을 이용한 실내 활동추적시스템을 제안하였다. 이를 위해 지자계 센서와 3축 가속도 센서를 사용한 신호 계측부와 Zigbee기반의 무선 센서 네트워크를 이용한 무선 전송부를 구성하였으며, 계측된 데이터의 분석으로부터 실내 위치추적의 가능성을 평가하였다.

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Development Plan of Package-type Instruments for Next-Generation Space Weather Observation Network

  • Choi, Seonghwan;Kwak, Young-Sil;Lee, Wookyoung
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.2
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    • pp.77.2-77.2
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    • 2021
  • Starting with the observation of sunspots in 1987, Korea Astronomy and Space Science Institute (KASI) has developed and installed various ground-based instruments for space weather research in Korea. Recently, SNIPE and CODEX are also being developed as space-based instruments. Expansion of the observation area and simultaneous observation have become important in the study of space weather. We have started Next-Generation Space Weather Observation Network Project this year. In order to establish a solar observation network, we planned to develop the Next Solar Telescope (NxST) which is a solar imaging spectrograph, and to install three NxST in the northern hemisphere. And we also planned to develop the Thermosphere-Ionosphere-Mesosphere Observation System (TIMOS), Global Navigation Satellite System (GNSS), and Geomagnetic packages, and install them in about ten sites over the world, for the purpose of establishing a global observation network for the near-earth space weather. We can take simultaneously observed space weather data in the global area, and are expecting it will play an important role in the international community for space weather research. We also have a strategy to secure observational technologies necessary for big space missions in the future, through this project.

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