Heading Degrees, magnetic
M = magnetic
Magnetic Sensor heading in degrees
Magnetic Deviation, degrees
Magnetic Deviation direction, E = Easterly, W = Westerly
Magnetic Variation degrees
Magnetic Variation direction, E = Easterly, W = Westerly
If HDG message also contains the variation and E/W flags then O will use that. If not then it will look in RMC message for a variation. If nothing there it will use WMM plugin unless user has selected the variation manually in options.
Heading Degrees, true
T = True
To be sent by a navigation receiver when a destination waypoint is active.
''
14
1 2 3 4 5 6 7 8 9 10 11 12 13| 15
| | | | | | | | | | | | | | |
$--RMB,A,x.x,a,c--c,c--c,llll.ll,a,yyyyy.yy,a,x.x,x.x,x.x,A,m,*hh<CR><LF>''
Field Number:
Status, A= Active, V = Void
Cross Track error - nautical miles
Direction to Steer, Left or Right
TO Waypoint ID
FROM Waypoint ID
Destination Waypoint Latitude
N or S
Destination Waypoint Longitude
E or W
Range to destination in nautical miles
Bearing to destination in degrees True
Destination closing velocity in knots
Arrival Status, A = Arrival Circle Entered
FAA mode indicator (NMEA 2.3 and later)
Time (UTC)
Status, V = Navigation receiver warning
Latitude
N or S
Longitude
E or W
Speed over ground, knots
Track Made Good, degrees true
Date, ddmmyy
Magnetic variation, degrees
E or W
Latitude
N or S (North or South)
Longitude
E or W (East or West)
Waypoint Name
Total number of messages being transmitted
Message Number
Message Mode
c = complete route, all waypoints
w = working route, the waypoint you just left, the waypoint you're heading to, then all the rest
Waypoint ID
More Waypoints
Universal Time Coordinated (UTC)
Latitude
Longitude
GPS Quality Indicator
Number of satellites in view, 00 - 12
Horizontal Dilution of Precision (HDOP)
Antenna altitude above/below mean-sea-level (geoid)
Units of antenna altitude, meters
Geoidal separation, the vertical difference between the WGS-84 elipsoid and the geoid
Units of geoidal separation, meters
Age of differential GPS data, time in seconds since last SC104
Differential reference station ID, 0000-102
Latitude
N or S (North or South)
Longitude
E or W (East or West)
Time (UTC)
Status A - Data Valid, V - Data Invalid
Number of sentences for full data / sentence 1 of 2
Number of satellites in view
Satellite PRN number
Elevation, degrees
Azimuth, degrees
SNR - higher is better / for up to 4 satellites per sentence
Track Degrees
T = True
Track Degrees
M = Magnetic
Speed Knots
N = Knots
Speed Kilometers Per Hour
K = Kilometers Per Hour
Note: Some autopilots, Robertson in particular, misinterpret “bearing from origin to destination” as “bearing from present position to destination”. This is likely due to the difference between the APB sentence and the APA sentence. for the APA sentence this would be the correct thing to do for the data in the same field. APA only differs from APB in this one field and APA leaves off the last two fields where this distinction is clearly spelled out. This will result in poor performance if the boat is sufficiently off-course that the two bearings are different.
Field Number:
Status V = LORAN-C Blink or SNR warning V = general warning flag or other navigation systems when a reliable fix is not available
Status V = Loran-C Cycle Lock warning flag A = OK or not used
Cross Track Error Magnitude
Direction to steer, L or R
Cross Track Units, N = Nautical Miles
Status A = Arrival Circle Entered
Status A = Perpendicular passed at waypoint
Bearing origin to destination
M = Magnetic, T = True
Destination Waypoint ID
Bearing, present position to Destination
M = Magnetic, T = True
Heading to steer to destination waypoint
M = Magnetic, T = True
Cross track error, measured
General warning flag V = warning
(Loran-C Blink or SNR warning)
Not used for GPS (Loran-C cycle lock flag)
Cross track error distance
L - Steer left to correct error (or R for right)
N- Distance units - Nautical miles
Time (UTC)
MMSI Number
Latitude
Longitude
Speed Knots
Heading
Course over Ground
Rate of turn
Navigation status
Latitude
Longitude
Speed over ground
Course over ground
MMSI, navigational status, ship type, call sign, destination, sizes (in AIS target list)
Target Number (0-99)
Target Distance
Bearing from own ship
Bearing Units
Target Speed
Target Course
Course Units
Distance of closest-point-of-approach
Time until closest-point-of-approach “-” means increasing
“-” means increasing
Target name
Target Status
Reference Target
Target Number (not used/ignored)
Latitude
Longitude
Name
Status
Reference Target (not used/ignored)
Heading, degrees true
Status, A = Data Valid
Vessel Course, degrees True
Course Reference
Vessel Speed
Speed Reference
Vessel Set, degrees True
Vessel drift (speed)
Speed Units
Latitude
Hemisphere N/S
Longitude
Hemisphere E/W
Altitude in meters above sea level
Speed over ground in knots
Heading over ground in degrees
Date
Time UTC
Name of buddy this position info belongs to.
For more details on how OpenCPN interprets all recognized sentences, look at the “AIS_DecoderA.cpp” file in the source code. For the Dashboard plugin, look at the different files in the “nmea0183” directory.
DBT - Depth Below Transducer
DPT - Depth of Water
GGA - Global Positioning System Fix Data
GLL - Geographic Position - Latitude/Longitude HDG Heading - Deviation & Variation
HDM - Heading - Magnetic
HDT - Heading - True
MTA - Air Temperature (obsolete)
MDA - Meteorological Composite (obsolete)
This message is obsolete and NMEA recommends to use XDR transducer messages instead.
However, old instruments might still sending this message.
OpenCPN reads the second value “Barometric pressure, bars”, but only if the number provided is between 0.8 and 1.1
All other values are ignored.
''
$--MDA,x.x,I,**x.x,B**,x.x,C,x.x,C,x.x,x.x,x.x,C,x.x,T,x.x,M,x.x,N,x.x,M*hh<CR><LF> \\
| | | | | | | | | | | \\
| | | | | | | | | | Wind speed, meters/second \\
| | | | | | | | | Wind speed, knots \\
| | | | | | | | Wind direction, degrees Magnetic \\
| | | | | | | Wind direction, degrees True \\
| | | | | | Dew point, degrees C \\
| | | | | Absolute humidity, percent \\
| | | | Relative humidity, percent \\
| | | Water temperature, degrees C \\
| | Air temperature, degrees C \\
| **//Barometric pressure, bars// ** \\
Barometric pressure, inches of mercury''
MTW - Mean Temperature of Water
VLW - Distance Traveled through Water
MWD - Wind Direction & Speed
MWV - Wind Speed and Angle
RMC - Recommended Minimum Navigation Information
RSA - Rudder Sensor Angle
VHW - Water speed and heading
VTG - Track made good and Ground speed
VWR - Relative Wind Speed and Angle
VWT - True Windspeed and Angle (obsolete)
XDR - Transducer Values
1 2 3 4 n \\
| | | | | \\
* $--XDR,a,x.x,a,c--c, ..... *hh<CR><LF> \\
Field Number:
1) Transducer Type
2) Measurement Data
3) Units of measurement
4) Name of transducer
x) More of the same
n) Checksum
Example:
$IIXDR,C,19.52,C,TempAir*3D
$IIXDR,P,1.02481,B,Barometer*0D
Measured Value | Transducer Type | Measured Data | Unit of measure | Transducer Name
------------------------------------------------------------------------------------------------------
barometric | "P" pressure | 0.8..1.1 or 800..1100 | "B" bar | "Barometer"
air temperature| "C" temperature | 2 decimals | "C" celsius | "TempAir" or "ENV_OUTAIR_T"
pitch | "A" angle |-180..0 nose down 0..180 nose up | "D" degrees | "PTCH"
rolling | "A" angle |-180..0 L 0..180 R | "D" degrees | "ROLL"
water temp | "C" temperature | 2 decimals | "C" celsius | "ENV_WATER_T"
-----------------------------------------------------------------------------------------------------
See details for AIVDO above in list.
NMEA version 2.3.added a mode indicator to many sentences to indicate what
kind of fix the receiver has. The value can be one of
A=autonomous
D=differential
E=Estimated
N=not valid,
S=Simulator.
Sometimes there can even be a null value as well.
The A and D are the only vales that will indicate an Active and reliable Sentence.
This mode character has been added to the end of RMC, RMB, VTG, and GLL sentences.
Optionally, to some others as well, including the BWC and XTE sentences.