LONG-RANGE AUTOMATIC IDENTIFCATION SYSTEM BROADCAST MESSAGE (MESSAGE 27)
This message is primarily intended for long-range detection of AIS Class A and Class B “SO” equipped vessels (typically by satellite). This message has a similar content to Messages 1, 2 and 3, but the total number of bits has been compressed to allow for increased propagation delays associated with long-range detection. Note there is no time stamp in this message. The receiving system is expected to provide the time stamp when this message is received.
|
Parameter
|
Bits
|
Description
|
|
Message ID |
6 |
Identifier for this message; always 27 |
|
Repeat indicator |
2 |
Always 3 |
|
User ID |
30 |
MMSI number |
|
Position accuracy |
1 |
As defined for Message 1 |
|
RAIM flag |
1 |
As defined for Message 1 |
|
Navigational status |
4 |
As defined for Message 1 |
|
Longitude |
18 |
Longitude in 1/10 min (±180°, East = positive (as per 2’s complement), West = negative (as per 2’s complement)
181° (1A838h) = position older than 6 hours or not available = default)
|
|
Latitude |
17 |
Latitude in 1/10 min (±90°, North = positive (as per 2’s complement), South = negative (as per 2’s complement)
91° (D548h) = position older than 6 hours or not available = default) |
|
SOG |
6 |
Knots (0-62); 63 = not available = default
|
|
COG |
9 |
Degrees (0-359); 511 = not available = default
|
|
Position Latency |
1 |
0 = Reported position latency is less than 5 seconds; 1 = Reported position latency is greater than 5 seconds = default
|
|
Spare |
1 |
Set to zero, to preserve byte boundaries
|
|
Total Number of bits |
96 |
|
