• Title/Summary/Keyword: Navigation Channel

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A Study on The Status of Vessel Restricted in Her Ability to Manoeuvre in Narrow Channel (좁은 수로에서의 조종제한선의 항법상 지위)

  • Ji, Sang-Won
    • Journal of Navigation and Port Research
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    • v.34 no.10
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    • pp.833-838
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    • 2010
  • The Supreme Court in Korea judged the conduct of vessels in narrow channel was applied in order to prevent a ship collision in narrow channel, regardless of kind of a ship or weather situation, as application was not excluded as vessel restricted in her ability to manoeuvre without other special circumstances such as receiving the right of keep her course and speed from the other vessel, any priority was not guaranteed for vessel restricted in her ability to manoeuvre in regard to the other vessel following the conduct of vessel in narrow channel. In this judgement, there is concern to cause disorder to interpretation in the rule of narrow channel and responsibility between vessels. Therefore, this study aims to suggest correct interpretation about the rule concerned.

Design of Advanced PCM Encoder Architecture for Efficient Channel Information Memory Management (효율적인 채널 정보 메모리 관리를 위한 PCM 엔코더 설계)

  • Ro, Yun-Hee;Kim, Geon-Hee;Kim, Dong-Young;Kim, Bok-Ki;Lee, Nam-Sik
    • Journal of Advanced Navigation Technology
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    • v.24 no.4
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    • pp.305-313
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    • 2020
  • Telemetry system is a system that transmits status information data acquired from the aircraft to the ground station. PCM encoder needs memory to store channel information in order to generate a frame format using the acquired data. Generally, telemetry systems in large aircraft require much larger memory for the increased acquisition channel information due to the increased sensors and subsystems. However, they have difficulty to store all channel information in limited memory. In this paper, we suggests and implements an advanced PCM encoder that can efficiently manage memory by minimizing duplicated channel information. This novel PCM encoder allocates duplicated channel information to memory only once. And, sub commutation channels having different information for each minor frame are allocated to the memory by multiples of sub commutation channels. Finally, the suggested PCM encoder was proved by simulation that composed channels of various measurement cycles.

Performance Evaluation of UWB Positioning System in Ultra Wideband Indoor Environment (광대역 실내 환경에서 UWB 위치 추정 시스템의 성능 평가)

  • Roh, Jae-sung
    • Journal of Advanced Navigation Technology
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    • v.25 no.5
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    • pp.357-362
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    • 2021
  • UWB(ultra wide band) communication systems employ short pulses to transmit information which spreads the signal energy over a very wide frequency spectrum. Received signal-to-noise power ratio of UWB signals is an important factor in determining the accuracy of a positioning system. As the signal to noise power ratio gets higher, positioning errors decrease since noise becomes less effective. Calculation of signal to noise power ratio as a function of communication distance provides important guidelines for the system design. And the performance of a positioning system also depends heavily on the channel model. As a result of the analysis, it was found that the performance of the received signal to noise power ratio according to the communication distance was better in the LOS channel environment than in the Non LOS(line of sight) channel environment. And as the symbol interval of the preamble signal increases at a specific communication distance, the channel capacity of the UWB system increases.

A Study on the Frequency Analysis of Available Channels in TVWS around the West Sea of Korea (Incheon-Jejudo) (대한민국 서해상 (인천-제주도)에서의 TVWS 가용채널 주파수 분석에 관한 연구)

  • Chung, Chanhyung;Cha, Jaesang;Shim, Dongha
    • Journal of Advanced Navigation Technology
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    • v.26 no.5
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    • pp.261-271
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    • 2022
  • This paper is the study in Korea to secure new frequency resources available at sea among terrestrial DTV (Digital TV) broadcasting bands. Focusing on Incheon and Jejudo in the west Sea of Korea, the possibility of using TVWS frequencies of DTV broadcast signals (channels 14-51, 470~698 MHz) was studied. According to the analysis, three channels, channel 19 (503 MHz), channel 37 (611 MHz) and channel 39 (623 MHz) can be used as TVWS available channels without interference with DTV in all nearby seas such as Incheon Port and Jeju Port. On the other hand, two channels, Channel 23 (527 MHz) and Channel 33 (587 MHz), were divided into strong DTV signals in the section between Incheon Port and Jeju Port, making it difficult to use them as available frequencies for TVWS on the west coast.

Study on the Fairway Used by Coastal Passenger Ship at Mokpo Port (목포항 입출항 연안여객선의 이용 항로에 관한 고찰)

  • Lee, Li-Na;Lee, Hong-Hoon
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.4
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    • pp.525-532
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    • 2022
  • The port of Mokpo operates the largest number of coastal passenger ships and routes in Korea. These coastal passenger ships pass through narrow channels in the south-west coast of Korea owing to the geographical effect. It is difficult to find a research for the safety of the marine traffic environment in the narrow channel used by coastal passenger ship. Therefore, in this study, the navigation safety of the target coastal passenger ship was analyzed in the narrow channel near the port of Mokpo using the Korea design standard for port and harbour facilities. As a result of the analysis, the width of the narrow channel between Maek-island and Dali-island is narrower than 1.5 times of the target ship's length over all, the degree of curvature of the narrow channel exceeds the standard value of 30°, and several fishing gears exist near the narrow channel. Finally, the following were suggested to improve the safety of navigation on the narrow channel: keeping one-way traffic during the day-time, and navigating through the designated fairway during night·visibility restriction·low tide.

Assessment of a Low Power Offset BPSK Component for Spreading Code Authentication

  • Maier, Daniel S.;Pany, Thomas
    • Journal of Positioning, Navigation, and Timing
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    • v.9 no.2
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    • pp.43-50
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    • 2020
  • In this paper a low power Spreading Code Authentication (SCA) sequence with a BPSK(1) modulation at a frequency offset of +7.161 MHz is tested for authentication purposes, the Galileo E1OS is used as base signal. The tested signals comprise a Galileo constellation with 5 satellites including the Galileo OS Navigation Message Authentication (OSNMA) and a low power offset BPSK (OBPSK(7,1)) as SCA component. The signals are generated with the software based MuSNAT-Signal-Generator. The generated signals were transmitted Over-The-Air (OTA) using a Software-Defined-Radio (SDR) as pseudolite. With a real-environment-testbed the performance of the SCA in real channel conditions (fading and multipath) was tested. A new SCA evaluation scheme is proposed and was implemented. Under real channel conditions we derive experimental threshold values for the new SCA evaluation scheme which allow a robust authentication. A Security Code Estimation and Replay (SCER) spoofing attack was mimicked on the real-environment-testbed and analyzed with the SCA evaluation scheme. It was shown that the usage of an OBPSK is feasible as an authentication method and can be used in combination with the OSNMA to improve the authentication robustness against Security SCER attacks.

Performance Improvement of OFDM Systems in Broadband Wireless Communication Channel Environments (광대역 무선통신 채널 환경에서 OFDM 시스템의 성능개선)

  • Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.11 no.1
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    • pp.37-42
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    • 2007
  • In this paper, we analyzed the performance of OFDM systems with adaptive equalizer that considers the frequency offset, the frequency non-selective fading, and two-path microwave Rummer's model channels. First of all, it is analyzed that the performance degradation, which is caused by the offset and the non-selective fading channel, through simulation. As the results of the simulation, the performance of the OFDM system is greatly influenced by the offset and channels. The more the frequency offset is, the worse the performance of the OFDM system is. However, if the adaptive equalizer is adopted to the OFDM system, the performance is enhanced up to the limited rang.

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In Summer, the Origin of Tsushima Warm Current Water in the Western Channel of the Korea Strait-2 on the Water in the Middle Layer (하계 대한해협 서수도에 유입되는 Tsushima난류수의 기원-2 중층수에 대한 고찰)

  • 윤종휘
    • Journal of the Korean Institute of Navigation
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    • v.14 no.2
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    • pp.61-76
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    • 1990
  • It was found that three different water masses were vertically situated in the western channel of the Korea Strait in summer. Of these water masses , the origin and inflow path of the middle water were discussed and estimated by comparing with water characteristics of neighbouring sea. As a result, (1) the middle water is formed on the continental shelf in the East China Sea by the mixing of the Kuroshio Water and Chinese Continental Coastal Water, (2) the middle water seems intruded through the sea around 127 E west off Kyushu Island and east off Cheju the Island.

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Performance Analysis of Watermarking using Audio and Image Watermark in Wireless Channel Environment (무선 전송 채널 환경에서 오디오와 로고 영상을 이용한 워터마킹 성능분석)

  • Kim, Yoon-Ho;Park, Ki-Hong
    • Journal of Advanced Navigation Technology
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    • v.10 no.4
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    • pp.406-412
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    • 2006
  • In this paper, we analyzed the performance of digital watermarking by using audio signal as well as logo image watermark. By utilizing the OFDM/QPSK system under AWGN channel environment, watermarked image are transmitted and detected. Experimental results showed that audio signal-based watermark embedding scheme is superior to that of logo image-based, which is able to restore a signal at SNR=3[dB].

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Performance Analysis of DS-CDMA System of Phase Estimation Error for Mobile Satellite Wireless Communication Channel (이동위성 무선통신 채널에서 위상추정 에러가 있는 DS-CDMA 시스템의 성능 해석)

  • Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.11 no.2
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    • pp.170-176
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    • 2007
  • In this paper, we improve performance for system when the carrier recovery signal is not perfect in the multipath mobile wireless communication fast fading channel based on DS-CDMA system. In the case, we use the phase estimation, diversity and adaptive FEC code technique in order to overcome this carrier phase error and mobile wireless fading. As a results in DS-CDMA system, we know that the appropriate use of diversity and adaptive FEC code technique reduced considerably performance degradation due to phase error.

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