Observation of AIS signal coverage from Mount Sumbing compared to AIS data from VTS Semarang

Abstract Automatic Identification System (AIS) is designed to operate on very high frequency (VHF) with the propagation characteristics limited to the principle of line of sight, where AIS receiver radio installed on coast radio station with a 100-metres-high antenna able to only monitor ships within 56 km. Considering such limitations, IMO has proposed a concept for positioning the AIS receiver antenna at the highest elevation to enhance the vessel surveillance range. To prove the concept, a survey of AIS reception has been conducted in Central Java in four different locations at different elevations, from 30 to 3,371 metres. The method employed was radio wave propagation prediction simulation at certain elevations, followed by AIS signal reception survey. The result indicated that from elevation of 3,371 metres, it could reach all coastal areas in Central Java to Surabaya Western Access Channel (SWAC). The implication of this study shows that it is potentially possible to construct support AIS stations to improve the performance of AIS coastal radio stations in Central Java in order to monitor vessels throughout this region with its 600 km of northern coastline and 300 km of southern coastline.