AIS PRODUCTS DESCRIPTION

1.1 AYSTEM OVERVIEW

AIS is one of the latest AtoN equipments allowing real-time information exchanged between Vessels and Traffic Service system.

AIS uses marine VHF channel with frequency set universally from 156.025MHz to 162.025MHz. AIS applies the broadcast method of time division multiple access (hereinafter called “TDMA”) TO transmit in a 2250 messages per minute rate. The whole broadcasting process does not require manual operating and it automatically generates networks so vessels can be easily identified with each other.

AIS system is capable of integrating and combining with other maritime system such as Electronic Chart System (hereinafter called “ECS”). AIS’ wide applications and its exception AtoN value greatly enhance other maritime systems’ performance.

Having an AIS system on board not only can monitor the status of the vessels in the surrounding sea, but also to receive the dynamic information (position, speed, SOG, and etc),

Static information, and voyage related information from any vessels equipped with an AIS system.

1.2. AIS COVERAGE

The system radio coverage will be similar to other VHF radio applied products. However,

How far the AIS system can transmit will also depends on the length of its external Antenna and the earth’s curvature. The longer of the antenna, and the higher it is set, will have slight difference in how far signal will transmit. Generally, the AIS signal coverage will be around 25 nautical miles.

1.3. AIS V.S. RADAR

Each AIS equipped vessel automatically broadcasts its own vessel information and will not encounter signal blocked out by capes or islands. AIS system also updates and broadcasts its speed, voyage related information and etc constantly. Comparing with Radar system, AIS system is much more effective in showing a vessel’s real-time voyage status and to provide collision avoidance warming beforehand.

AIS system is primarily designed for the purpose of collision avoidance. It greatly enhances the add-on value of other maritime system such as the ARPA Radar, VTS, and etc. An AIS-integrated ECS system can easily plot all vessels’ information, such as vessels’ names, position, headings, and etc on its plotter.

1.4. TYPE OF AIS

While there are Class A, Class B, and Receiver type AIS, their intended nature to navigate are different.

Table 1-1 Type of AIS

1.5. AIS DATA INFORMATION

In the following table, some data details are lighted I black and these data are mandated, by law, to be transmitted and received from Class A AIS equipped vessels only.

Table 1-2 AIS data information

1.6. AIS REPORT RATE

A Class B AIS has two different data report rates. One report rate is in accordance to ITU-RM. 1371 standard with SOTDMA broadcasting method. The other is in accordance to IEC62287 standard with CSTDMA broadcasting method. For details please refer to the following tables.

SOTDMA Broadcasting Method:

Table 1-3-1 AIS report rate

AIS is with CSTDMA Broadcasting Method as follows:

Picture 1-3-2 AIS report rate