問題詳情

請依下文回答第 51 題至第 55 題：      The Automatic Identification System (AIS) is a short-range coastal tracking system currently used on ships.It was developed to provide identification and positioning information to both 51 and shore stations. Shipsof 300 gross tonnage or more sailing on international voyages, freighter ships of 500 gross tonnage or moresailing in local waters, and all passenger ships 52 size are required by the International MaritimeOrganization to carry AIS equipment. AIS transponders automatically broadcast information at regular 53 .Navigational status data is transmitted every 2 to 180 seconds, depending on a ship’s activity. In addition, voyagerelated data is broadcast every 6 minutes. These signals are received by AIS transponders installed on other shipsor by land-based systems.      The AIS signals have a horizontal range of about 40 nautical miles, 54 that AIS traffic information isonly available around coastal zones or in a ship-to-ship zone. AIS communication takes place using two VHFfrequencies, 161.975 MHz and 162.025 MHz. Although only one radio channel is necessary, each stationtransmits and receives over two radio channels to avoid interference problems and to allow channels to be shiftedamong ships 55 communication loss.
51
(A)commuters  
(B)terminals
(C)  referees
(D)vessels 

參考答案

答案：D
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

內容推薦

內容推薦