User's Manual

NACOS Platinum
ED 3100 G 140 / 04 (2011-11)
Operating Instructions
F-1 AIS
F SENSORS.fm / 10.11.11
F-10
1.5 Channel Management
The AIS system cannot function unless all AIS systems communicate on the same VHF channels and
unless the communication bandwidth and the transmission level are correctly set. The settings needed
for this are normally made automatically as described in the following.
VHF channels 2087 (161.975 MHz) and 2088 (162.025 MHz) are used worldwide for the two AIS chan-
nels.
As default values, AIS channel A uses the VHF channel 2087, the AIS channel B uses the VHF channel
2088, and for both channels, the bandwidth setting is Auto, and transmission is performed with power
level High. Every mobile AIS station operates on these two channels. A mobile AIS station is thus
capable of receiving two messages, from two different stations concurrently, provided that it does not
transmit at the same time.
In particular geographical regions or situations, i.e. due to local RF interference, it is necessary to deviate
from these settings. The necessary values are received via the AIS channels from a local VTS centre,
harbour administration etc.
These data also contain the information about the region in which these settings are to be used,
including the transition zone surrounding that region.
The switch-over is performed automatically when the ship is
located in the transition zone. This is done in the following steps:
- As soon as the ship reaches the boundaries of the transition
zone, one AIS channel is set to the different VHF settings
(with the other AIS channel remaining unchanged) and the
alarm Channel management changed is shown. As a result,
the targets situated inside and on either side of the transition
zone are now seen and the ship is also seen by these targets;
see the diagram.
- On leaving the transition zone, the second AIS channel is also
switched over to the different VHF settings.
The general effect is that a ship which is not located in the transi-
tion zone does not see any targets located behind the transition
zone.
The transponder is capable of managing 8 different zones auto-
matically. Each zone is described by the South-West and North-
East corner of a rectangle.
Each zone may have different channel management settings. Administrations may set your AIS by special
messages automatically to a certain locally required setting. You can check these settings, which are
stored in your AIS, by opening the tabs for channel and zone. You can toggle from one to the next
settings by using the Next button. Although manual setting is also available, it is strongly recommended
not to use the manual function. This should only be done on special advice of a local administration i.e.
by radio or other means if the automatic function is not available from coastside. There is a severe risk,
It is also possible to make a setting manually, but this should only be done in
exceptional cases and following the advice of a local administration received by
radio, publications, etc. and only after having informed the ship's command
personnel accordingly. For manual setting, see chapter "Displaying the Channel
Data Set" on page F-11.
C
A
E
D
B
F
Transition
zone
Region with
different VHF
settings
Sees
Sees
B, C, D
A, B, D, E, F
Sees
C, D, F
Area with
default VHF
settings