Transas T214, Technical Manual

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Settings of Base Station configuration
Chapter 6. Commissioning.Internal configuration
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to the Base Station, and indicates that the start slot has not been set, i.e. is
unavailable, when the ECB sentence is received from the Base Station.
4. For messages other than message 17, this field is 1. For message 17 the
number may range from 1 to 4 consecutive slots. 3 slots are recommended for
each DGNSS service.
5. Slot Interval ranging from 30 to 13500 in slots (epoch of 6 minutes) , between
broadcasts of ITU-R M.1371 messages 17, 20, 22, or 23 on Channels “A” or “B”.
Interval selection for message 17 should consider the timing needs for both
DGNSS corrections and integrity warnings. 5 seconds or less is recommended.
A value of 0 indicates only one broadcast.
DLM (A). DLM (B) – Data Link Management slot allocations for Base
Station
This sentence is setup in the Configuration->Setup->BS setup->DLM(A) and
Configuration->Setup->BS setup->DLM(B) menu.
This sentence provides the Base Station with the slot allocations to be reserved for
FATDMA Base Station broadcasts. This sentence provides the Base Station with the
information necessary to broadcast an ITU-R M.1371 Message 20 “Data link
management message”, which informs mobile AIS units of the reserved FATDMA
slots. Upon receipt of this sentence the Base Station will reserve the provided
FATDMA slot allocations within its frame map, and will be ready to generate
Message 20 when instructed to do so via the CBM or ECB sentence. This is the
information that is broadcast on the VDL using message 20. (Reference ITU-R
M.1371-1, §3.3.8.2.16 (Also see CBM and ECB)). The shore station is responsible
for filtering out slot reservation conflicts that may exist. The Base Station is not
responsible for detecting these conflicts. These conflicts in the shore station network
must be resolved separately from entering the data. The AIS Base Station, upon
receipt of a Query for this sentence, will generate a response to the requestor
consisting of multiple DLM sentences containing all the FATDMA reserved slots.
Field values:
DLM # – Number of Sequence (0 – 9). From template sequence number (Like the
sequence number method used in the ACA/ACS sentence pair, this number is used
to identify and address each DLM sentence record stored in the Base Station.) Note:
The sequence number is used to associate the DLM field data with each of the AIS
VDL “message 20’s” that are broadcast by the Base Station“.