Technical reference
Page 63
6.8.12 LRF - Long range function
This sentence is used in long range interrogation requests and interrogation replies.
6.8.13 LRI - Long range interrogation
The long-range interrogation of the AIS is accomplished through the use of two sentences. The pair of
interrogation sentences, a LRI-sentence followed by a LRF-sentence, provides the information needed by an
AIS to determine if it must construct and provide the reply sentences (LRF, LR1, LR2, and LR3).
$--LRF,x,xxxxxxxxx,c--c,c--c,c--c*hh<CR><LF>
Field
number
Description
1 x Sequence number , 0 to 9
2 xxxxxxxxx MMSI of requestor
3 c--c Name of requestor, 1 to 20 character string
4 c--c Function request, 1 to 26 characters from:
A = Ship’s name, call sign and IMO number
B = Date and time of message composition
C = Position
E = Course over ground
F = Speed over ground
I = Destination and ETA
O = Draught
P = Ship / Cargo type
U = Ship’s length, breadth and type
W = Persons on board
5 c--c Function reply status:
2 = Information available and provided in the following LR1, LR2, or LR3 sen-
tence
3 = Information not available from AIS transceiver
4 = Information is available but not provided (i.e. restricted access determined
by ship's master)
$--LRI,x,a,xxxxxxxxx,xxxxxxxxx,llll.ll,a,yyyyy.yy,a,llll.ll,a,yyyyy.yy,a*hh<CR><LF>
Field
number
Description
1 x Sequence number, 0-9
2 a Control Flag
3 xxxxxxxxx MMSI of "requestor"
4 xxxxxxxxx MMSI of “destination”
5 llll.ll,a Latitude - N/S
6 yyyyy.yy,a
Longitude - E/W (north-east co-ordinate)
7 llll.ll,a
Latitude - N/S
8 yyyyy.yy,a Longitude - E/W (south-west co-ordinate)
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