AIS2 what is inside AIS submessage for message 01,02,03

Communications State

Parameter	Bits	Description
Sync state (seebelow)	2	0 UTC direct (sync from own integral GPS receiver) 1 UTC indirect (own GPS unavailable - UTC sync from GPS receiver on nearby ship or base station) 2 Station is synchronized to a base station (base direct - GPS unavailable). 3 Station is synchronized to another station based on the highest number of received stations or to another mobile station, which is directly synchronized to a base station (GPS unavailable)
Slot time-out	3	Specifies frames remaining until a new slot is selected 0 means that this was the last transmission in this slot 1-7 means that 1 to 7 frames respectively are left until slot change
Sub message	14	The sub message depends on the current value in slot time-out as described in Table 19

* The communication state field covers 19 bits and this is general to both message 1, message 2 and message 3. The
* content is though different for the different communication states applied by the different message types.
*
* This message type is using SOTDMA communication state, which is described below.
*
* CommState - 19 bits, which are:
sync state: 2 bits
slot timeout: 3 bits
sub message: 14 bits
*
* The sub message depends upon the value of the slot timeout. The slot timeout is defined to be between 0 and 7 both values included.
*
* The sub message is defined as:

* When slot timeout = 0 - Then the sub message is the slot offset: If the slot time-out value is 0 (zero) then the slot offset should indicate the offset to the slot in which transmission will occur during the next frame.
 If the slot offset is zero, the slot should be de-allocated after transmission
*
* When slot timeout = 1 - Then the sub message is UTC hour and minute: If the station has access to UTC, the hour and minute should be indicated in this sub message. Hour (0-23) should be coded in bits 13 to 9 of the sub message (bit* 13 is MSB). Minute (0-59) should be coded in bit 8 to 2 (bit 8 is MSB). Bit 1 and bit 0 are not used.
*
* When slot timeout = 2,4,6 - Then the sub message is the slot number: Slot number used for this transmission (between
* 0 and 2249).
*
* When slot timeout = 3,5,7 - Then the sub message is the recieved stations: Number of other stations (not own station)
* which the station currently is receiving (between 0 and 16383).