Friday, December 23, 2011

Standard format of NAVTEX messages


The standard format of NAVTEX message:
Phasing signal > 10 second
ZCZC Start of message group
B1 B2 B3 B4 B1: Transmiter, B2: Subject indicator, B3 B4: Message number
Time of origin Optional
Message text
NNNN End of message
Idle signal aa……a > 2 seconds
End of emmission.
The Transmitter Identification Character (B1):
Transmitter identification character is a single unique identifier which is allocated to each transmiter. It is used to identify the broadcasts which are to be accepted by the receiver and those which are to be rejected, and also the time slot for transmission.
Subject Indicator Characters (B2)
Information is grouped by subject on the NAVTEX broadcast and each subject group is allocated a subject indicator character.
The subject Indicator character is used by receiverr to identify different classes of message. the Indicator is also used to reject messages which aren’t required by theVessel. Receivers also use the B2 character to identify message which, because of their importance may not be rejected.
The following subject indicator Characters from A to Z are in use :
A = Navigational Warnings (can’t be rejected by the receiver)
B = Meteorologi Warnings (can’t be rejected by the receiver)
C = Ice Reports (found when we sailing in the cold area)
D = Search and Rescue information also pirate attack warnings (this also can’t be rejected by the receiver)
E = Meteorological Forecasts
F = Pilot Services Messages
G = AIS
H = LORAN Messages
I = Spare
J = SATNAV Message
K = Other Electronic Navaid Messages (concerning radio Navigation service)
L = Navigational Warning-additional to letter A (should not be rejected at the receiver (continuation of B2 subject group “A”))
V = Special services – allocation by NAVTEX Panel
W = Special services – allocation by NAVTEX Panel
X = Special services – allocation by NAVTEX Panel
Y = Special services – allocation by NAVTEX Panel
Z = No Message on hand
Message Numbering (B3 B4)
Each message within a subject group is allocated a serial number, B3 B4, between 01 and 99. This number will not necessarily relate to series numbering in other Radio Navigational Warning systems.
On reaching 99 will re-commence at 01 but avoiding the use of message number still in force.
A shortage of numbers will, where possible, be alleviated by the allocation of messages to other relevant subject groups. it has been found that 99 messages are not always enough for some subject groups, and B2 = L may be used for additional Navigational Warnings, to receive the overflow from B2 = A when necessary.
See the table bellow:
Common Abbreviations for International NAVTEX Services
Terminology in fullNAVTEX Abbreviations
Northeast or NortheasterlyNE
East or EasterlyE
SouthEast ShouthEasterlySE
South or SotherlyS
SouthWest or SouthWesterlySW
West or WesterlyW
Northwestly or NorthwestlyNW
DecreasingDECR
IncreasingINCR
VariableVRB
BecomingBECMG
LocallyLOC
ModerateMOD
OccasionallyOCNL
ScatteredSCT
Temporary / TemporarilyTEMPO
IsolatedISOL
Frequent / FrequencyFRQ
ShowersSHWRS
Cold FrontC-FRONT / CFNT
Warm FormW-FRONT / WFNT
Occlusion FrontO-FRONT / OFNT
WeakeningWKN
BuildingBLDN
FillingFLN
DeepeningDPN
Intensifiying / IntensifyINTSF
Improving / ImproveIMPR
StationarySTNR
Quasi-StationaryQSTNR
Move / MovingMOV / MVG
VeeringVEER
BackingBACK
SlowlySLWY
QuicklyQCKY
RapidlyRPDI
KnotsKT
Km / hKMH
Nautical MilesNM
MetresM
HectoPascalHPA
Meteo..MET
ForecastFCST
Further OutlooksTEND
VisibilityVIS
SlightSLGT or SLT
QuadrantQUAD
PossiblePOSS
ProbablePROB
SignificantSIG
No ChangeNC
No SinificantNOSIG
FollowingFWL
NextNXT
HeavyHVY
SevereSEV / SVR
StrongSTRG
FromFM
ExpectedExp
Latitude / LongitudeLAT / Long
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