Physical link:
AIS
msg_ID:
14
Extended description:
Safety related data for broadcast communication
Priority:
2
Access scheme:
RATDMA
ITDMA
FATDMA
Communication state:
N/A
Transmitted by:
Mobile station
Base station
The safety related broadcast message could be variable in length, based on the amount of safety related text. The length should vary between 1 and 5 slots.
Additional bit stuffing will be required for this message type. For details refer to transport layer, § 5.2.1, Annex 2.
Table 64 gives the number of 6-bit ASCII characters, so that the whole message fits into a given number of slots. It is recommended that any application minimizes the use of slots by limiting the number of characters to the numbers given, if possible:
These numbers also take bit stuffing into account.
The AIS-SART should use Message 14, and the safety related text should be:
1) For the active SART, the text should be “SART ACTIVE”.
2) For the SART test mode, the text should be “SART TEST”.
3) For the active MOB, the text should be “MOB ACTIVE”.
4) For the MOB test mode, the text should be “MOB TEST”.
5) For the active EPIRB, the text should be “EPIRB ACTIVE”.
6) For the EPIRB test mode, the text should be “EPIRB TEST”.
TABLE 63
| Parameter | Number of bits | Description |
|---|---|---|
| Message ID | 6 | Identifier for Message 14; always 14. |
| Repeat indicator | 2 | Used by the repeater to indicate how many times a message has been repeated. See § 4.6.1, Annex 2; 0-3; 0 = default; 3 = do not repeat any more |
| Source ID | 30 | MMSI number of source station of message |
| Spare | 2 | Not used. Should be set to zero. Reserved for future use |
| Safety related text | Maximum 968 | 6-bit ASCII as defined in Table 47 |
| Maximum number of bits | Maximum 1 008 | Occupies up to 3 slots, or up to 5 slots when able to use FATDMA reservations. For Class B “SO” mobile AIS stations the length of the message should not exceed 3 slots For Class B “CS” mobile AIS stations the length of the message should not exceed 1 slot |
Additional bit stuffing will be required for this message type. For details refer to transport layer, § 5.2.1, Annex 2.
Table 64 gives the number of 6-bit ASCII characters, so that the whole message fits into a given number of slots. It is recommended that any application minimizes the use of slots by limiting the number of characters to the numbers given, if possible:
| Number of slots | Maximum 6-bit ASCII characters |
| 1 | 16 |
| 2 | 53 |
| 3 | 90 |
| 4 | 128 |
| 5 | 161 |
These numbers also take bit stuffing into account.
The AIS-SART should use Message 14, and the safety related text should be:
1) For the active SART, the text should be “SART ACTIVE”.
2) For the SART test mode, the text should be “SART TEST”.
3) For the active MOB, the text should be “MOB ACTIVE”.
4) For the MOB test mode, the text should be “MOB TEST”.
5) For the active EPIRB, the text should be “EPIRB ACTIVE”.
6) For the EPIRB test mode, the text should be “EPIRB TEST”.