• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.2
• /
• pp.107-112
• /
• 2011

Several developed countries have been developing their own satellite navigation systems, such as Europe's Galileo, China's BEIDOU, and Japan's QZSS, to cope with clock errors and signal vulnerabilities of GPS. In addition, modernization of Loran, eLoran, for GPS backup has been conducted. In Korea, a dependent navigation system has been required and for GPS backup, the need for utilization of time synchronization infrastructure through the modernization of Loran has been raised. Loran signal uses 100Khz groundwave. A significant factor limiting the ranging accuracy of the Loran signal is the ASF arising from the fact that the groundwave signal is likely to propagate over paths of varying conductivity and topography. Thus, an ASF compensation method is very important for Loran and eLoran navigation. This paper introduces the propagation delay model and then compares and analyzes the estimations from the propagation delay model and measured ASFs.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.12
• /
• pp.2326-2332
• /
• 2011

eLoran is enhanced Loran-C and eLoran is researched for as GPS backup system because this system is resistant to signal interference and has high accuracy. TOA measurements of eLoran include errors proportional to the range such as PF, SF, ASF and EF. Therefore these error factors must be compensated for improved accuracy of position. Generally, error models or GPS aided compensation methods are used, but these methods are limited by lack of infrastructure or system performance. Therefore, this paper proposes new model of error factors included in eLoran TOA measurements and navigation algorithm using this model. Error factors in this model are sum of a certain size of error and error proportional to the range. And feasibility and performance of proposed navigation algorithm are verified by using raw measurements.

• Journal of information and communication convergence engineering
• /
• v.8 no.5
• /
• pp.524-527
• /
• 2010

As the GPS(Global Positioning System) vulnerabilities were introduced, alternative systems to GPS backup have been studied for several years. Enhanced Loran(eLoran) as the worldwide ground-based supplementary radio navigation system was recommended as the cost effective alternative to GPS backup. Many efforts on adoption of eLoran as GPS backup have been presented. The US has been the leading role and announced that 70% enhancement for eLoran was established last year. However, the Obama administration cut off the eLoran budget on the fiscal year 2010 budget proposal while GAO's reports submitted that GPS service gap would be possible just some years later. Besides the US's condition, there are still many positive opinions on eLoran to GPS backup. This paper introduces the historical and technical aspects of eLoran and Korea's research topics.

• Journal of Advanced Navigation Technology
• /
• v.23 no.4
• /
• pp.289-295
• /
• 2019

Maritime back-up navigation system in port approach requires a horizontal accuracy of 10 meters in IALA (International Association of Lighthouse Authorities) recommendations. eLoran which is a best back-up navigation system that satisfies accuracy requirement has poor navigation performance depending signal environments. Especially, noise caused by multipath and electronic devices around eLoran antenna affects navigation performance. In this paper, Ship based Navigation Back-up system using UAV on Interference is designed to satisfy horizontal accuracy requirement. To improve the eLoran signal environment, UAVs are equipped with camera, IMU sensor and eLoran antenna and receivers. This proposed system is designed to receive eLoran signal through UAV-based receiver and control UAV's position and attitude within Landmark around area. The ship-based positioning using eLoran signal, vision and attitude information received from UAV satisfy resilient and robust navigation requirements.

• Journal of Navigation and Port Research
• /
• v.46 no.6
• /
• pp.525-529
• /
• 2022

In the eLoran system, the Loran Data Channel (LDC) is used to provide precise timing and positioning. The LDC message can be modulated with the Eurofix method, which modulates the transmission time of the 3rd-8th pulse not used for navigation, and the 9th pulse method, which modulates data using the 9th additional pulse after the existing 8 Loran pulses. In this paper, we analyzed the reception performance of the LDC message transmitted from the eLoran transmitter according to the modulation method. The eLoran testbed transmitter in Incheon was set to transmit LDC messages simultaneously with the 9th pulse modulation method and the Eurofix modulation method. Then, the LDC messages stored in the databases of the eLoran differential stations in Incheon and Pyeongtaek were analyzed in terms of the message reception rate according to the modulation method. Using the navigation aid management ship Inseong No. 1, the range of LDC message reception of actual sea users near Incheon Port was also analyzed. The results of this study are expected to be utilized in the full operational capability service after the eLoran pilot service.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.11a
• /
• pp.166-168
• /
• 2023

기존 eLoran 수신기는 보정기준국(인천·평택항 반경 30km 이내에서만 이용 가능하며 ASF 맵보정 정보를 저장하는데 한계가 있음. 자체 오차정보를 보정하는 기능을 가진 eLoran/GPS 통합수신기의 알고리즘 및 성능 분석을 통해 더 넓은 해역에서 eLoran 서비스를 백업항법시스템으로 이용하기 위한 기반 마련

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2017.11a
• /
• pp.196-198
• /
• 2017

미국, 러시아, 중국 등 선진국에서는 GNSS와 같은 위성항법시스템의 취약성에 대한 대비하기 위한 고정밀도의 지상파 전파항법시스템을 독자적으로 개발하여 운영 중에 있지만, 우리나라는 1979년도에 도입한 외산장비로 포항 및 광주 송신국을 구축하여 Loran-C 체인으로 지상파 전파항법시스템을 운영 중에 있다. 특히 위성항법시스템이 없는 우리나라 입장에서는 어느 위성항법시스템에 종속되지 않는 고정밀도의 지상파 eLoran 전파항법시스템 개발이 더욱 절실히 요구되고 있다. 본 연구 개발에서는 고정밀도의 eLoran 지상파 항법시스템 개발에 앞서 eLoran 송수신 시스템을 검증하고, 실제 공간상의 채널환경을 모사할 수 있는 eLoran emulator를 개발하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.11a
• /
• pp.169-171
• /
• 2023

eLoran 신규송신국 구축 진행현황을 확인하고 eLoran 전국망 지상기반 PNT 서비스의 안정 제공을 위한 울릉도, 제주도 신규송신국 구축 가능한 해수부 부지를 사전 검토하고 부지 특성에 따른 안테나 설계 적합성 및 성능을 검토하여 적정한 안테나 배치안을 제시하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.12
• /
• pp.1053-1058
• /
• 2016

The eLoran(enhanced Long Range Navigation) transmitting antenna is analyzed for co-location with an AM transmitting antenna in an MF transmitting site. To compensate for the loading effect, the umbrella-type loading is applied for eLoran antenna. The validity of the co-location between the MF antenna and the eLoran antenna is verified through the simulation results of the radiation pattern and the return loss. Also, coupling including antenna matching circuit is analyzed to verify the effect of the transmitting circuit. The coupling between the LF and eLoran antenna is -53.3 dB at 100 kHz and -64.8 dB at 1,053 kHz, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2012.10a
• /
• pp.353-355
• /
• 2012

차세대 LF 송신기의 성능 및 구성요소 등을 확인하여, LORAN과 eLORAN 시스템 송신기로의 활용 여부와 이 송신기를 사용시 eLORAN 시스템에 미치는 영향 등을 다루고자 한다.