Ais; System Definitions - Standard Horizon CP190i Owner's Manual

14. AIS

AIS is an Automatic Identification System. It has been introduced to improve the safety of
navigation by assisting in the efficient operation of ship-to-ship locaion reporting and VTS
applications. The system should enable operators to obtain information from the ship
automatically, requiring a minimum of involvement of ship's personnel, and should have a high
level of availability. AIS transponders installed on IMO vessels use VHF frequencies to:
· Transmit details of their own vessel
· Receive details from other vessels or navigation aids within VHF range.
STANDARD HORIZON GPS Chart Plotters are able to display AIS target (for collision
avoidance) on the Chart page and AIS list pages when connected to a AIS receiver (GX2100
or GX2150 STANDARD HORIZON VHF/AIS transceiver) or transponders which output
NMEA 0183 VDM sentence at 38400 or 4800 baud. The Chart Plotters are able to show
targets from both Class A (commercial) and Class B targets.
14.0

SYSTEM DEFINITIONS

· Target: It is a vessel equipped with AIS. Information about the targets is being received
by AIS Receiver and displayed on the screen.
· CPA : Closest Point of Approach is the closest distance that will be achieved between
your vessel and the tracked target, based on your vessel's speed and direction and the
target's speed and direction.
· CPA Limit: This is the distance from your vessel that a target may reach before a target
is deemed a threat.
· CPA Alarm: Occrs if CPA is less or equal to CPA Limit. This test is done for active
targets only.
· TCPA: Time to Closest Point of Approach is the tme remaining until the CPA will occur.
· TCPA Limit: This is the time remaining before the CPA is reached.
· TCPA Alarm: Occurs if TCPA is less or equal to TCPA Limit. This test is done for active
targes only and if CPA value is less or equal to CPA Limit.
· Radio Call Sign: International call sign assigned to essel, often used on voice radio.
· Name: Name of ship, 20 characters.
· MMSI: Maritime Mobile Service Identity.
· MMSI number: A unique 9 digit number that is assigned to a DSC radio station It
primarily registers the boat information in the U.S. Coast Guard' national distress
database for use in emergency situations.
· Active Target: Target located within the Activation Range. Active target is represeted
by oriented triangle with COG and Heading vectors. Rate of turn may also be displayed.
· Dangerous Target: Target detectedby CPA or TCPA Alarm. Dangerous target is Ative
Target by definition. For better visibility Dangerous Target symbol is flashing.
· Sleeping Target: Target located outside the Activation Range. Sleeping target is
represented by a small oriented triangle.
Lost Target: When the AIS info is not received from that vessel for 3.5 minutes. The
presentation will be a flashing black triangle with a cross through.
· Activation Range: Range around your boat where targets become active. AIS target
CP190i and CPF190i Page 99