| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a vessel automatic identification system(AIS) by which the changeover of a service frequency due to a movement or the like to the territorial waters of a specific nation from the high seas can be performed automatically and at low costs as far as possible in a vessel which uses a broadcasting-type AIS. SOLUTION: In an AIS control apparatus 10, a positioned-result utilization- type frequency decision means is installed. By the positioned-result utilization- type frequency decision means, a sea area in which an own vessel exists at present is discriminated on the basis of an own-vessel position obtained from a positioning device, and a service frequency in a broadcasting-type AIS is decided. The AIS control apparatus 10 controls a transmitter 12 and receivers 14, 16 for the broadcasting-type AIS in such a way that a transmitting operation and a receiving operation are performed at the service frequency decided in the manner.</p> |
