Group assignment command

msg_ID: 
23
Description: 
Assignment of a specific report behaviour by competent authority using a Base station to a specific group of mobiles
Priority: 
1
Access scheme: 
FATDMA
RATDMA
Communication state: 
N/A
Transmitted by: 
Base station

The Group assignment command is transmitted by a base station when operating as a controlling entity(see § 4.3.3.3.2 Annex 7 and § 3.20). This message should be applied to a mobile station within the defined region and as selected by “Ship and Cargo Type” or “Station type”. The receiving station should consider all selector fields concurrently. It controls the following operating parameters of a mobile station:
–           transmit/receive mode;
–           reporting interval;
–           the duration of a quiet time.
Station type 10 should be used to define the base station coverage area for control of Message 27 transmissions by Class A and Class B “SO” mobile stations. When station type is 10 only the fields latitude, longitude are used, all other fields should be ignored. This information will be relevant until three minutes after the last reception of controlling Message 4 from the same base station (same MMSI).

 
TABLE 76

Parameter Number of bits Description
Message ID 6 Identifier for Message 23; always 23
Repeat indicator 2 Used by the repeater to indicate how many times a message has been repeated.
0-3; default = 0; 3 = do not repeat any more
Source ID 30 MMSI of assigning station
Spare 2 Spare. Should be set to zero
Longitude 1 18 Longitude of area to which the group assignment applies; upper right corner (north-east); in 1/10 min
(±180°, East = positive, West = negative)
Latitude 1 17 Latitude of area to which the group assignment applies; upper right corner (north‑east); in 1/10 min
(±90°, North = positive, South = negative)
Longitude 2 18 Longitude of area to which the group assignment applies; lower left corner (south-west); in 1/10 min
(±180°, East = positive, West = negative)
Latitude 2 17 Latitude of area to which the group assignment applies; lower left corner (south‑west); in 1/10 min
(±90°, North = positive, South = negative)
Station type 4 0 = all types of mobiles (default); 1 = Class A mobile stations only; 2 = all types of Class B mobile stations; 3 = SAR airborne mobile station;
4 = Class B “SO” mobile stations only; 5 = Class B “CS” shipborne mobile station only;
6 = inland waterways; 7 to 9 = regional use; 10 = base station coverage area
(see Message 4 and Message 27); 11 to 15 = for future use
Type of ship and cargo type 8 0 = all types (default)
1...99 see Table 53
100...199 reserved for regional use
200...255 reserved for future use
Spare 22 Not used. Should be set to zero. Reserved for future use
Tx/Rx mode 2 This parameter commands the respective stations to one of the following modes:
0 = TxA/TxB, RxA/RxB (default); 1 = TxA, RxA/RxB, 2 = TxB, RxA/RxB,
3 = reserved for future use
Reporting interval 4 This parameter commands the respective stations to the reporting interval given in Table 77
Quiet time 4 0 = default = no quiet time commanded; 1-15 = quiet time of 1 to 15 min
Spare 6 Not used. Should be set to zero. Reserved for future use
Number of bits 160 Occupies one-time period
 

 

 
TABLE 77
Reporting interval settings for use with message 23

Reporting interval field setting Reporting interval for Message 23
0 As given by the autonomous mode
1 10 min
2 6 min
3 3 min
4 1 min
5 30 s
6 15 s
7 10 s
8 5 s
9 Next shorter reporting interval
(only applicable if in autonomous mode)
10 Next longer reporting interval
(only applicable if in autonomous mode)
11 2 s (not applicable to the Class B “CS” and Class B “SO”)
12-15 Reserved for future use
NOTE 1 – When the dual channel transmission is suspended by Tx/Rx mode command 1 or 2, the required reporting interval should be maintained using the remaining transmission channel.