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NMEA 0183 Messages
Receipt of a VHF transmission on either AIS radio channel causes a VDM message to be output via
the data port.
VDM Message Format
!--VDM,x1,x2,x3,a,s--s,x*hh<CR><LF>
x1 = Total number of sentences needed to transfer the message , 1 to 9
x2 = Sentence number, 1 to 9
x3 = Sequential message identifier, 0 to 9
a = AIS Channel, "A" or "B"
s - - s = Encapsulated ITU-R M.1371 radio message
x = Number of fill-bits, 0 to 5
VDM Message Types
For example, the information contained in the s - - s portion of the VDM = Encapsulated ITU-R
M.1371 radio message. Note that messages 5 and 19 may be sent as multi part messages using
the x1, x2 and x3 parameters for message sequence control
VDO Message Format
This sentence sends the own vessels details.
Message Format
!--VDO,x1,x2,x3,a,s--s,x*hh<CR><LF>
x1 = Total number of sentences needed to transfer the message , 1 to 9
x2 = Sentence number, 1 to 9
x3 = Sequential message identifier, 0 to 9
a = AIS Channel, "A" or "B"
s - - s = Encapsulated ITU-R M.1371 radio message 4
x = Number of fill-bits , 0 to 5
ACA Message Format
The SAS SERIES unit can receive regional channel management information (ACA) in two ways:
ITU-R M.1371 message 22 or a DSC telecommand received on channel 70,
Message Format
$--ACA,x,llll.ll,a,yyyyy.yy,a,llll.ll,a1,y1y1y1y1y.y1y1,a2,x1,x2x2x2x2,
x3,x4x4x4x4, x5,x6,x7,a3,x8,hhmmss.ss*hh <CR><LF>
x = Sequence Number , 0 to 9
IIII, II, a = Region Northeast corner latitude – N/S
yyyyy.yy,a1 = Region Northeast corner longitude – E/W
llll.ll,a = Region Southwest corner latitude – N/S
y1y1y1y1y1.y1y1,a2 = Region Southwest corner longitude – E/W
x1 = Transition Zone Size
x2x2x2x2 = Channel A
x3 = Channel A bandwidth
x4x4x4x4 = Channel B
x5 = Channel B bandwidth
x6 = Tx/Rx mode control
x7 = Power level control
a3 = Information source
x8 = In-Use Flag
hhmmss.ss = Time of "in-use" change
