Multiple slot binary message with communications state

msg_ID: 
26
Description: 
Scheduled binary data transmission (Broadcast or addressed)
Priority: 
4
Access scheme: 
SOTDMA
RATDMA
ITDMA
FATDMA
Communication state: 
SOTDMA
ITDMA
Transmitted by: 
Mobile station
Base station

This message is primarily intended for scheduled binary data transmissions by applying either the SOTDMA or ITDMA access scheme. This multiple slot binary message can contain up to 1 004 data-bits (using 5 slots) depending on the coding method used for the contents, and the destination indication of broadcast or addressed. See application identifiers in § 2.1, Annex 5.
This message should not be acknowledged by either Message 7 or 13.

 

TABLE 82
Parameter Number of bits Description  
Message ID 6 Identifier for Message 26; always 26  
Repeat indicator 2 Used by the repeater to indicate how many times a message has been repeated. Refer to § 4.6.1, Annex 2; 0-3; default = 0; 3 = do not repeat any more  
Source ID 30 MMSI number of source station  
Destination indicator 1 0 = Broadcast (no Destination ID field used)
1 = Addressed (Destination ID uses 30 data bits for MMSI)
 
Binary data flag 1 0 = unstructured binary data (no Application Identifier bits used)
1 = binary data coded as defined by using the
      16-bit Application identifier
 
Destination ID 0/30 Destination ID (if used) If Destination indicator = 0 (Broadcast); no data bits are needed for the Destination ID.
If Destination indicator = 1; 30 bits are used for the Destination ID and 2 spare bits for byte alignment.
 
Spare bits 0/2 Spare (if Destination ID used)  
Binary data Broadcast Maximum 104 Application identifier
(if used)
16 bits Should be as described in § 2.1, Annex 5
  Addressed Maximum 72 Application binary data Broadcast Maximum 88 bits
Addressed Maximum 56 bits
Application specific data
Binary data added by 2nd slot 224 Allows for 32 bits of bit-stuffing
Binary data added by 3rd slot 224 Allows for 32 bits of bit-stuffing
Binary data added by 4th slot 224 Allows for 32 bits of bit-stuffing
Binary data added by 5th slot 224 Allows for 32 bits of bit-stuffing
Spare 4 Needed for byte alignment
Communication state selector flag 1 0 = SOTDMA communication state follows
1 = ITDMA communication state follows
Communication state 19 SOTDMA communication state (see § 3.3.7.2.1, Annex 2), if communication state selector flag is set to 0, or ITDMA communication state (§ 3.3.7.3.2, Annex 2), if communication state selector flag is set to 1
Maximum number of bits Maximum 1 064 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. Class B “CS” mobile AIS stations should not transmit
 

 

 
Table 83 gives the maximum number of binary data-bits for settings of destination indicator and coding method flags, such that, the message does not exceed the indicated number of slots.

Destination indicator Binary data flag Binary data (maximum bits)
1-slot 2-slot 3-slot 4-slot 5-slot
0 0 104 328 552 776 1000
0 1 88 312 536 760 984
1 0 72 296 520 744 968
1 1 56 280 504 728 952