Ais 6 - Regional Areas - Leica MX420 Operator's Manual

Operator's Manual
AIS 6 - REGIONAL AREAS
Automatic Identifaction System
Two VHF and one DSC receiver channels have been designated for AIS use world-
wide. These frequencies are:
• AIS I (Channel 87B, 161.975 MHz, (2087)
• AIS 2 (Channel 88B, 162.025 MHz, (2088)
• DSC (Channel 70, 156.525 MHz)
Under normal masterless operation, the MX423 AIS transponder operates autono-
mously with other ships or AIS base stations using the AIS I & 2 frequencies.
When entering areas controlled by a competent authority (i.e. Coast Guard) under
Vehicle Tracking System (VTS) rules, the MX423 AIS transponder can be polled
and controlled by the YTS station. In this situation, data communication between
ship-to- ship and ship-to-shore stations are done through the DSC frequency (chan-
nel 70). All YTS related activities are happening without any user intervention.
The controlling YTS base station schedules all ship's data transmission and pro-
vides the regional parameters shown in AIS 6 display, such as:
• Operating frequency, bandwidth and mode of Channel A & B receivers
• Northeast and Southwest corner coordinates ofthe region
• Zone size
• Date and time tag
These parameters are stored in the memory bank ofthe AIS transponder and can be
displayed in the
MX420/AIS
CDU. Up to eight regions can be stored by the
transponder. The AIS constantly checks the stored region boundaries and com-
pares it to its own position. If the distance to the region boundaries is greater than
500 miles from its own position or the time tag was older than five weeks, those
stored regions will be erased from memory.
The operator (administrator) has the option to do a full or partial editing of the
regional parameters when needed. The conditions below have to be observed
when editing:
• Use the correct channel numbers (see table A-I, page 143 or in the AIS card)
• Latitude difference should be no less that 20 NM or larger than 200 NM
• Longitude difference should be no less than 20 NM or larger than 200 NM
• The zone size should be no less than I square mile or larger than 8 square
miles
• Distance to the zone is less than 500 NM from you current position
Manual entries violating any of the above conditions will be rejected by the AIS
transponder without notifying the operator. If the region memory is full, the oldest
regional memory will be replaced by a newly accepted one.
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Version 1.5