A Study on the Analysis and Modeling of Maritime VHF Wave Propagation- Based on AIS Sea Trials in Coastal Waters of Taiwan

• Main Authors: Wei-Chao Wang, 王威超
• Other Authors: Shwu-Jing Chang
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/89366344995221730801

碩士 === 國立海洋大學 === 導航與通訊系碩士班 === 91 === Automatic Identification System (AIS), which integrates the mobile communication and satellite positioning technologies, has great potential in contributing to navigation safety and maritime security. All vessels subject to the Safety of Life at Sea Convention（SOLAS）are required to be fitted with AIS within a very tight schedule. It is therefore of urgency needs of AIS researches to support the planning and implementations of shore-based AIS facilities and services. However, as compared with the situation on land, field measurements with sea trials are really costly, subject to weather/sea conditions and vessel motions, even restricted in route by the concern about navigation safety. Available database of the coastal land area such as the digital terrain model is also rather incomplete due to either the remoteness or confidential factors. This study focuses on making the most use of limited sea trial measurements and environmental database for the planning of AIS shore-based facilities. Matlab numerical methods and the Mapinfo geographical information system (GIS) are used for the simulation and analysis of AIS signal propagation in the maritime VHF band around 162MHz. Lee Model, which takes field measurement and terrain height data as important parameters, is adopted for the simulation. Research area mainly covers coastal waters of northern Taiwan and the Kaohsiung Harbor, where sea trials are performed by using an AIS base station and a class A AIS mobile station. Comparison between field measurements and simulations by linear regression analysis shows that the difference in path loss slope is about 1.3dB/dec, corresponding to a coverage range difference about 3.7km in the case of northern coastal waters. While the difference in path loss slope is only about 0.35dB/dec, corresponding to a coverage range difference about 0.2km in the case of Kaohsiung Harbor. Considering the fact that measurements were taken at a much worse sea state for the case of northern Taiwan than the case of Kaohsiung Harbor, the simulation fits well with the measurement, especially when in calm sea. Consequently, the mention presented should be applicable to large-scale predictions along the coast of Taiwan with reasonable results.