B&G NAIS-400 - Manual (Page 9)

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About your AIS class B transceiver | NAIS-400 User Manual
About your AIS class B transceiver
About AIS
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 vessels. Position is derived from the
Global Positioning System (GPS) and communication between ves-
sels is by Very High Frequency (VHF) digital transmissions.
There are a number of types of AIS device as follows:
• Class A transceivers. These are similar to class B transceivers, but
they are designed to be fitted on large vessels such as cargo ships
and large passenger vessels. Class A transceivers transmit at a higher
VHF signal power than class B transceivers and therefore can be
received by more distant vessels, and also transmit more frequently.
Class A transceivers are mandatory on all vessels over 300 gross
tonnes on international voyages and certain types of passenger ves-
sels under the SOLAS regulations.
• Class B transceivers. Similar to class A transceivers in many ways,
but are normally lower cost due to the less stringent performance
requirements. Class B transceivers transmit at a lower power and at a
lower reporting rate than class A transceivers.
• AIS base stations. AIS base stations are used by Vessel Traffic Sys-
tems to monitor and control the transmissions of AIS transceivers.
• Aids to Navigation (AtoN) transceivers. AtoNs are transceivers
mounted on buoys or other hazards to shipping which transmit
details of their location to the surrounding vessels.
• AIS receivers. AIS receivers will generally receive transmissions
from class A transceivers, class B transceivers, AtoNs and AIS base sta-
tions but do not transmit any information about the vessel on which
they are installed.
• This NAIS-400 product is an AIS Class B transceiver.
Isometric view
NAIS-400
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