Novel Multichain-Based Loran Positioning Algorithm for Resilient Navigation

Son, Pyo-Woong,Rhee, Joon Hyo,Seo, Jiwon IEEE 2018 IEEE transactions on aerospace and electronic syst Vol.54 No.2

<P>Intentional high-power global positioning system jamming is a significant threat for ships in the South Korean waters and has occurred multiple times in recent years. The South Korean government intends to utilize the existing long-range navigation (Loran) infrastructure to provide a backup navigation capability to maritime users. However, the observed accuracy of a conventional Loran positioning fix during a field test in Incheon, South Korea, was 592.88 m, far from the 20-m accuracy that the South Korean government tries to provide. The largest error source for Loran is the additional secondary factor (ASF) delay. A conventional time of flight based ASF correction is not applicable in Northeast Asia because several transmitters are not synchronized to universal time coordinated. Thus, we propose a time difference of arrival based ASF correction method that is applicable to the existing Loran signals in Northeast Asia. The demonstrated accuracy with this correction was 32.12 m when using a single Loran chain for positioning. In order to utilize the full capability of the observed signals from the five transmitters of two Loran chains in the region, we further propose a novel multichain-based Loran positioning algorithm. By applying this algorithm together with the ASF correction method, we achieved a 15.32-m accuracy with 100% position availability. This result shows the potential of the existing Loran transmitters in Northeast Asia to provide a reliable and accurate backup maritime navigation service.</P>

Analysis of Range Measurement Based on MF DGNSS Infrastructures

Pyo-Woong Son,Younghoon Han,Kiyeol Seo,Tae Hyun Fang 사단법인 항법시스템학회 2022 Journal of Positioning, Navigation, and Timing Vol.11 No.4

As location-based services using the Global Navigation Satellite System (GNSS) are diversified, concerns about the vulnerability of GNSS to radio disturbance and deception are also growing. Accordingly, countries that own and operate GNSS, such as the United States, Russia, and Europe, are also developing additional navigation systems that can compensate for GNSS' weaknesses. Among them, an R-Mode system that transmits navigation signals using an infrastructure that transmits differential GNSS (DGNSS) information using signals from the medium frequency band currently in operation is being developed in Europe and Korea. Since 2020, Korea has improved four DGNSS transmission stations, including Chungju, Eocheongdo, Palmido, and Socheongdo, to transmit R-Mode signals and test navigation performance in some parts of the West Sea. In this paper, we intend to establish a testbed for measuring the distance of R-Mode signals currently being ransmitted and analyze the results. It is confirmed that the distance measurement performance varies depending on the antenna type, diurnal variation, and propagation path of the signal.

Compensation Method of eLoran Signal`s Propagation Delay and Performance Assessment in the Field Experiment

Pyo-Woong Son,Tae Hyun Fang,Sul Gee Park,Younghoon Han,Kiyeol Seo 사단법인 항법시스템학회 2022 Journal of Positioning, Navigation, and Timing Vol.11 No.1

The eLoran system is a high-power terrestrial navigation system that is recognized as the most appropriate alternative to complement the GNSS’s vulnerability to radio frequency interference. Accordingly, Korea has conducted eLoran technology development projects since 2016. The eLoran system developed in Korea provides 20 m positioning accuracy to maritime user in Incheon and Pyeongtaek harbor. To accurately calculate the position with the eLoran signal, it is necessary to apply a compensation method that mitigates the propagation delay. In this paper, we develop the compensation method to mitigate the eLoran signal propagation delay and evaluate the positioning performance in Incheon harbor. The propagation delay due to the terrain characteristics is pre-surveyed and stored in the user receiver. Real-time fluctuations in propagation delay compared to the pre-stored data are mitigated by the temporal correction generated at a nearby differential Loran station. Finally, two performance evaluation tests were performed to verify the positioning accuracy of the Korean eLoran system. The first test took place in December 2020 and the second in April 2021. As a result, the Korean eLoran service has been confirmed to provide 20 m location accuracy without GPS.

The Power Amplifier Control Design of eLoran Transmitter

Son, Pyo-Woong,Seo, Kiyeol,Fang, Tae Hyun 항법시스템학회 2021 Journal of Positioning, Navigation, and Timing Vol.10 No.3

In this paper, a study was conducted on the power amplifier control required to design an eLoran transmitter system using a low-height antenna. The eLoran transmitter developed during the eLoran technology development project conducted in Korea used a small 35 m antenna due to the difficulty of securing a site for antenna installation. This antenna height is very low compared to the height of 750 m which is required for eLoran 100 kHz signal transmission without any radiation loss. In the case of using such a small antenna, not only the radiation efficiency of the transmission is lowered, but also the power module control must be performed more precisely in order to transmit the eLoran standard signal. The equivalent RLC circuit of the transmitter system was implemented and transient analysis was conducted to derive the input required voltage for satisfying the output requirement. The voltage waveform was also generated by the RLC circuit analysis to generate the eLoran signal. Furthermore, we suggest power width modulation method to control eLoran power amplifier module more sophisticatedly.

A Study on Dynamic Safety Navigation Envelopes Considering a Ship’s Position Uncertainty

Pyo-Woong Son,Youngki Kim,Tae Hyun Fang,Kiyeol Seo 사단법인 항법시스템학회 2023 Journal of Positioning, Navigation, and Timing Vol.12 No.3

As technologies such as cameras, Laser Imaging, Detection, and Ranging (LiDAR), and Global Navigation Satellite Systems (GNSS) become more sophisticated and common, their use in autonomous driving technologies is being explored in various fields. In the maritime area, technologies related to collision avoidance between ships are being developed to evaluate and avoid the risk of collision between ships by setting various scenarios. However, the position of each vessel used in the process of developing collision avoidance technology between vessels uses data obtained through GNSS, and may include a position error of 10 m or more depending on the situation. In this paper, a study on the dynamic safety navigation range including the positional inaccuracy of the ship is conducted. By combining the concept of the protection level obtained using GNSS raw data with a conventional safe navigation range, a safer navigation range can be calculated for dynamic navigation. The calculated range is verified using data obtained while sailing in an actual sea environment.

인천 지역 Loran-C 수신현황 분석

손표웅(Pyo-Woong Son),서지원(Jiwon Seo) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6

위성항법시스템의 고정밀 측위기술 동향과 해양에서의 활용사례 조사

손표웅(Pyo-Woong Son),박슬기(Sul Gee Park),박상현(Sanghyun Park) 한국항해항만학회 2020 한국항해항만학회 학술대회논문집 Vol.2020 No.춘계

위성항법시스템을 활용한 측위 기술이 발전하면서, 여러 오차에 대한 보정정보를 이용해 보다 정밀한 위치 계산이 가능하게 되었다. 단방향으로 보정정보를 전송하여 미터 급의 정확도 서비스가 가능한 DGNSS가 현재 널리 사용되고 있는 대표적인 시스템이다. 하지만 정밀한 위치정보에 대한 수요가 증가함에 따라 센티미터 급의 위치 정확도에 대한 요구가 늘어나고 있다. Precise point positioning (PPP), real-time kinetic (RTK) 등의 기술들은 센티미터급의 위치 정확도를 제공하는 것으로 알려져 있지만, 초기 수렴시간, 서비스 커버리지, 보정정보 송수신을 위한 통신채널 등의 측면에서 여러 제약조건을 가지고 있다. 그렇기 때문에 근래에는 PPP와 RTK 기술을 융합하여 다양한 응용분야에서 활용할 수 있도록 PPP-RTK 기술이 개발되고 있다. 본 논문에서는 PPP-RTK 기술에 대한 동향에 대해 설명하고 해양분야에서의 활용 사례를 서술하였다. With the development of the positioning technology using the satellite navigation system, it is possible to calculate the position more precisely using correction information for various errors. DGNSS, which is capable of meter-level accuracy service by transmitting correction information in one direction, is a representative system currently widely used. However, as the demand for high-accuracy position information increases, there is a growing demand for centimeter-level position accuracy. Techniques such as precise point positioning (PPP) and real-time kinetic (RTK) are known to provide centimeter-level positioning accuracy, but have several constraints in terms of initial convergence time, service coverage, and communication channel for transmitting and receiving correction information. Therefore, novel high-accuracy positioning technology (PPP-RTK) is being developed to complement these constraints and it is utilized in various applications. This paper describes the recent trends in PPP-RTK technology and describes the applications in the maritime area.

고정밀 위성항법서비스의 무결성 감시 방안 분석

손표웅 ( Pyo-woong Son ),박슬기 ( Sul Gee Park ),박상현 ( Sang Hyun Park ),신유진 ( Yujin Shin ),송재영 ( Jaeyoung Song ),김의호 ( Euiho Kim ) 한국항행학회 2021 韓國航行學會論文誌 Vol.25 No.2

육상에서 자율주행차량이 본격적으로 개발됨에 따라 해상에서도 자율주행선박에 대한 국제적 논의가 계속되고 있고, 국제해사기구(IMO; International Maritime Organization)에서는 위성항법시스템을 이용해 10 cm 이하의 위치 정확도를 무결성 감시 기능과 함께 보장하도록 권고하고 있다. 10 cm 이하의 위치 정확도 성능을 제공하기 위해서는 위성신호의 반송파를 기반으로 고정밀 보정정보를 사용해야 한다. 또한 이에 대한 무결성을 감시하기 위해서는 각 보정정보 생성 과정에서 발생하는 오차를 overbounding 할 수 있어야 한다. 본 논문에서는 현재 운용되고 있는 고정밀 위성항법서비스 무결성 감시 방안에 대해 분석한다. 또한 미국에서 운용 중인 위성 기반의 광역보강시스템 (WAAS; wide area augmentation system)의 무결성 감시기법을 분석하고, 해양 지역에서의 고정밀 위성항법서비스의 무결성 감시 방안을 도출하였다. International Maritime Organization (IMO) recommends maintaining a positioning accuracy of global satellite navigation system (GNSS) within the range of 10 cm and monitoring its integrity. In order to provide the positioning accuracy of 10 cm or better, high-precision correction information must be used based on the carrier phase of the satellite signal. Furthermore, in order to monitor the integrity of this, the errors should be overbounded in the process of generating correction. In this paper, we analyze the GNSS integrity monitoring methods in high-precision position service currently in operation. The integrity monitoring technique of the wide area augmentation system (WAAS) of the U.S. is studied. As a conclusion, we propose the integrity monitoring method of Korean high-precision GNSS service in maritime area.

Development of the Simulator for FPC-G, the Focal Plane Fine Guiding Camera for SPICA

Jeonghyun Pyo,Woong-Seob Jeong,Chol Lee,Son-Goo Kim,Dae-Hee Lee,SPICA FPC Team 한국천문학회 2013 天文學會報 Vol.38 No.1

Development of MF R-Mode Transmitting System for Maritime Resilient PNT in the Republic of Korea

Younghoon Han,Pyo-Woong Son,Kiyeol Seo,Tae Hyun Fang 사단법인 항법시스템학회 2022 Journal of Positioning, Navigation, and Timing Vol.11 No.4

R-Mode is terrestrial based Global Navigation Satellite System (GNSS) backup radio navigation technology which used existing maritime information service infrastructure. It has advantages on reduce the cost and reutilize the frequency resource. In this paper, we propose a method to develop a medium-frequency (MF) band R-Mode transmitting station by utilizing the currently operating Differential GNSS (DGNSS) reference station infrastructure. To this end, the considerations for co-operating the DGNSS reference station and the MF R-Mode transmitting station are analyzed. In this process, we also analyze what is necessary to configure the communication system as a navigation system for range measurement. Based on the analysis result, MF R-Mode transmitting station system is designed and architecture is proposed. The developed system is installed in the field, and the performance evaluation results is presented.