한국항해항만학회지 (Journal of Navigation and Port Research)

  • 제34권3호
  • /
  • Pages.175-180
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  • 2010
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  • 1598-5725(pISSN)
  • /
  • 2093-8470(eISSN)
한국항해항만학회 (Korean Institute of Navigation and Port Research)
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ASF 예측치와 실측치 비교

Comparison of Predicted and Measured ASF

  • Shin, Mi-Young (Department of Electronics Engineering, Chungnam National University, Korea) ;
  • Hwang, Sang-Wook (Department of Electronics Engineering, Chungnam National University, Korea) ;
  • Yu, Dong-Hui (Department of Multimedia Engineering, Catholic University of Pusan, Korea) ;
  • Park, Chan-Sik (Department of Electronics Engineering, Chungbuk National University, Korea) ;
  • Lee, Chang-Bok (Time and Frequency Group, Korea Research Institute of Standard and Science, Korea) ;
  • Lee, Sang-Jeong (Department of Electronics Engineering, Chungnam National University, Korea)
  • 투고 : 2010.02.22
  • 심사 : 2010.04.09
  • 발행 : 2010.04.30
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초록

대부분의 응용분야에서 GNSS가 주 측위 시스템으로 활용되고 있으나, 방해전파에 대한 취약성으로 인해 최근에 몇몇 국가에서 eLoran 시스템을 GNSS 백업용으로 사용하기 위한 연구를 진행 중이다. eLoran 시스템의 구축을 위해서는 기존 Loran 시스템에서 설비의 업그레이드, 데이터 채널 사용, dLoran 사이트 추가 구성, 전파 지연오차 보상을 통한 성능 향상이 필요하다. eLoran 신호를 이용한 측위 시에 정확도 성능에 가장 큰 영향을 미치는 오차요소는 육지를 통해 전파될 때 겪는 부가적인 지연요소인 ASF이다. ASF는 지상파 신호가 전파시에 가변적인 고도, 유전율, 도전율 특성을 갖는 육지를 통과하며 발생하는 지연요소이다. 따라서 지상파를 이용한 항법 시에 ASF에 대한 보상모델을 설정하는 것은 매우 중요하다. 본 논문에서는 몬테쓰 모델 (Monteath's Model)을 사용하여 ASF 예측치를 모델링하고, Loran 신호를 이용한 실측을 통해 ASF 실측치를 측정한 후, ASF 예측치와 실측치를 비교하고 특성을 도출하였다. 실험대상 지역은 대전 KRISS와 포항 근방이며, GRI 9930 체인 중 주국인 포항 송신국의 신호를 사용하였다. 실험을 통해 ASF 실측치의 반복성을 확인하고, ASF 예측치와 실측치 간에 일정한 추이를 보이는 것을 확인하였다.

In the almost application parts, GNSS being used the primary navigation system on world-widely. However, some of nations attempt or deliberate to enhance current Loran system, as a backup to satellite navigation system because of the vulnerability to the disturbance signal. Loran interests in supplemental navigation system by the development and enhancement, which is called eLoran, and that consists of advancement of receiver and transmitter and of differential Loran in order to increase the accuracy of current Loran-C. A significant factor limiting the ranging accuracy of the eLoran signal is the ASF in the TOAs observed by the receiver. The ASF is mostly due to the fact that the ground-wave signal is likely to propagate over paths of varying conductivity and topography. This paper presents comparison results between the predicted ASF and the measured ASF in a southern east region of Korea. For predicting ASF, the Monteath model is used. Actual ASF is measured from the legacy Loran signal transmitted Pohang station in the GRI 9930 chain. The test results showed the repeatability of the measured ASF and the consistent characteristics between the predicted and the measured ASF values.

키워드

참고문헌

  1. 국승기, 김정훈, 김민철(2005), "한국의 LORAN-C 정책방향 수립에 관한 연구", 한국항해항만학회 제 29권 제 2호 추계학술대회논문집, pp. 163-168.
  2. "포항.광주 해상무선표지소 (2008), 기술마당, http://loran9930.go.kr/"
  3. Hartnett, C. R., Johnson, G., and Swaszek, P. (2004), "Navigation using an ASF Grid for Harbor Entrance and Approach", Institute of Navigation 60th Annual Meeting, pp. 200-210.
  4. ITU-R P.832-2 (1992), World ATLAS of Ground Conductivities, pp. 29.
  5. Johler, J.R., Kellar, W.J., and Walters, L.C. (1956), "Phase of the Low Radiofrequency Ground Wave", NBS Circular No. 573, pp. 1-38.
  6. Johnson, G., Hartnett, R., Swaszek, P., Moyer, T., and Shalaev, R. (2003), "Summer Vacation 2003 - ASF Spatial Mapping in CO, AR, FL, and CA", 32nd Annual Convention and Technical Symposium, International Loran Association.
  7. Johnson, G. W., Shalaev, J. R., Oates, C., Hartnett, C. R., and Swaszek, P. F. (2007), "4 Down, 50 to go - An Update on Harbor Surveys in the United States", 36th Annual Convention and Technical Symposium, International Loran Association.
  8. Keating, R.E., Lukac, C.F., Luther, G.H., and Charron, L.G. (1986), "Timing Calibration of the Northeast U.S.A. Loran-C Chain(9960)", 18th Annual PTTI Applications and Planning Meeting, pp. 331-351.
  9. Kuhn, M., Johnson, G., Wiggins, M., Swaszek, P., and Hartnett, C. R. (2006), "Warping Time and Space : Spatial Correlation of Temporal Variations", 35th Annual Convention and Technical Symposium, International Loran Association.
  10. Last, D., Williams, P., and Dykstra, K. (2000), "Propagation of Loran-C signals in Irregular Terrain-Modelling and Measurements : Part I : Modelling", 29th Annual Convention and Technical Symposium, International Loran Association.
  11. Lee, C.B., Yang, S.H., Lee, Y.K., Suh, S.H., Shin, M.Y., and Lee, S.J. (2009), "An Assessment Method for eLoran Performance using the Legacy Loran Signal", ENC-GNSS 2009.
  12. Luo, N., Mao, G., Lachapelle, G., and Cannon, E. (2006), "ASF Effect Analysis Using an Integrated GPS/eLORAN Positioning System", Institute of Navigation National Technical Meeting 2006, pp. 967-976.
  13. Monteath, G.D. (1978), "Computation of Groundwave Attenuation over Irregular and Inhomogeneous Ground at Low and Medium Frequencies", BBC Report 1978/7, pp. 1-18.
  14. NASA (2009), SRTM, "http://www2.jpl.nasa.gov/srtm/" Volpe National Transportation Systems Center, US Department of Transportation, Office of Assistant Secretary for Transportation Policy (2001), Vulnerability Assessment of the Transportation Infrastructure Relying on the Global Positioning System, Volpe Report
  15. Yang, S. H., Lee, C. B., Lee, Y. K., and Lee, S. J. (2009), "Design of ASF Measurements System in the Field", International Symposium on GPS/GNSS 2009.