The FA100 Transponder unit contains a VHF transmitter, two TDMA receivers on two parallel VHF channels, a DSC channel 70 receiver, interface, communications processor, LCD display, and an internal GPS receiver. The internal 12-channel all-in-view GPS receiver, with differential capability, provides UTC reference for system synchronization to eliminate a clash among multiple users. It also gives position, COG and SOG when the external GPS fails.

The LCD panel displays all required information about Static data, Dynamic data, Voyage related data and Short safety-related messages. The information and messages are automatically updated according to the ITU-R M.1371-1, e.g., static information every 6 min and on request, dynamic information every 10 s on ships faster than 3 kt and 3.3 s when changing course at 0-14 kt, etc.

The AIS enhances detection of other ships and aids to navigation (AtoN) on the radar screen.

• AIS targets are visible even if they are behind large ships, islands or points
• AIS is not obscured by the sea clutter and rain clutter
• Possible to predict course change of large ships by displaying ROT at tip of COG/SOG vector

The AIS target symbols can be overlaid on the following Furuno radars when RP radar plotting modules are connected: FAR-28x5 series, FR-21x5 series and FR-15x5 series. The RP radar plotting modules provide practically an unlimited number of AIS targets together with ARPA symbols.

Operation of the modules is the same for all RP models. Place the cursor on an AIS target of interest and hit the AIS Data Key, and the relevant data is visible on the data area below the ARPA data cell. If multiple AIS symbols mask the ARPA and radar picture, you can place the AIS targets in a sleep mode. The triangle symbols get smaller for positive observation of ARPA symbols.

The AIS target symbols appear as defined by SN/Circ.217 as follows: AIS COG/SOG vector changes it length with speed and adjustable in cycle time.

ROT mark is viewable at the COG/SOG vector tip when a target ship is equipped with a Furuno GPS compass SC60 or SC120.

AIS SYSTEM OVERVIEW

The Automatic Identification System (AIS) was originally developed to aid the Vessel Traffic Services (VTS) by use of VHF transponder working on Digital Selective Call (DSC) at VHF Channel 70 and is still in use along the UK coastal areas and others. Afterward the IMO developed a Universal AIS using a new sophisticated technology called Self-Organized Time Division Multiple Access (SOTDMA) based on a VHF Data Link (VDL).

This system is synchronized with GPS time to avoid conflict among multiple users (IMO minimum 2,000 reports per minute and IEC requires 4,500 reports on two channels).

The system operates in three modes – autonomous (continuous operation in all areas), assigned (data transmission interval remotely controlled by authority in traffic monitoring service) and polled (in response to interrogation from a ship or authority). The VHF channels 87B and 88B are commonly used and in addition there are local AIS frequencies. The shipborne AIS transponders exchange various data as specified by the IMO and ITU on either frequency automatically set up by the frequency management telecommand received by the DSC receiver on ship. VHF transmit power is also set up for 12.5 W or 2 W automatically.