Quark-elec Manual
3 of 18
2019
V1.0
1. Introduction
This manual provides installation procedures, configuration and safety instructions for the A051T Class B Transponder.
1.1. How AIS Works
AIS stands for Automatic Identification System. AIS is a location and vessel information reporting system. It allows
vessels equipped with AIS to automatically and dynamically share and regularly update their position, speed over
ground (SOG), course over ground (COG) and other information such as vessel identity with similarly equipped craft.
The marine Automatic Identification System (AIS) is a location and vessel information reporting system. It allows
vessels equipped with AIS to automatically and dynamically share and regularly update their position, speed, course
and other information such as vessel identity with similarly equipped craft. Position is derived from a Global Navigation
Satellite System (GNSS) network and communication between vessels is by Very High Frequency (VHF) digital
transmissions. A sophisticated and automatic method of time sharing the radio channel is used to ensure that even
where a large number of vessels are in one location, blocking of individual transmissions is minimised, any
degradation of the expected position reporting interval is indicated to the user and even if the unit suffers extreme
channel overload conditions it will always recover to normal operation.
1.2. AIS Classes
There are two classes of AIS transponders that can be fitted to vessels, Class A and Class B. In addition AIS base
stations may be employed by the Coastguard, port authorities and other authorized bodies. AIS units acting as aids to
navigation (AtoNs) can also be fitted to fixed and floating navigation markers such as channel markers and buoys.
Class A units are a mandatory fit under the safety of life at sea (SOLAS) convention to certain vessels types, including
those above 300 gross tons or which carry more than 11 passengers in International waters. Many other commercial
vessels and some leisure craft also fit Class A units. Class A AIS units transmit the radio signal at a power level of
12.5 watts, while class B is at 2 watts. Class B units are currently not a mandatory fit but authorities in several parts of
the world are considering this. Class B units are designed for fitting in vessels which do not fall into the mandatory
Class A fit category, but who still desire or are required for other reasons to transmit their AIS location.
Quark-elec A051T is a class B transponder.
A Class A unit will transmit its IMO number (if known), MMSI, Call sign and Name, length and beam, ship type, time,
course over ground (COG), speed over ground (SOG), heading, navigational status, rate of turn, draught, cargo type,
destination and safety related messages via NMEA transmit facility. Message lengths are variable with static and
voyage related information being transmitted less often.
Class A ship messages reporting intervals
Ships dynamic conditions
Rate
Ship at anchor or moored
3 min
Ship 0-14 Knots
10 sec
Ship 0-14 Knots and changing course
3.3 sec
Ship 14-23 Knots
6 sec
Ship 14-23 Knots and changing course
2 sec
Ship > 23 Knots
2 sec
Ship > 23 Knots and changing course
2 sec
Ships Static Information
3 min
A Class B AIS unit is designed to be interoperable with Class A units, but not to impact the Class A network. Many
commercial vessels, fishing boat, leisure craft, not classified as requiring a Class A unit, choose to install a Class B
unit to avoid accidents at sea. A Class B unit will transmit its MMSI, Call Sign and Name, length and beam, ship type,
time, course over ground (COG), speed over ground (SOG) only.
Class B ship messages reporting intervals
Ships dynamic conditions
Rate
Ship with Speed Over the Ground < 2 Knots
3 min
Ship with Speed Over the Ground > 2 Knots
30 sec
Ships Static Information
3 min
