NMEA National Marine Electronics Association

The NMEA is a set of standards established by the National Marine Electronics Association with the intent to bring marine devices together.

The NMEA Standard

Ripetitore NMEA
NMEA repeater

The NMEA corresponds to a series of communication protocols established by the National Marine Electronics Association, which owns the copyright, with the aim of identifying common standards for the exchange of information between marine devices, although its spread has made it suitable for use in other types of applications.

The most commonly used formats today are NMEA 0183 and NMEA 2000.

The NMEA 0183 has replaced the old NMEA 0180 and NMEA 0182 and the transmission is unidirectional, establishing a transmitting device called talker and one or more receivers called listener. The data transmission speed is usually 4.8 Kbps.

The NMEA 2000 is the most advanced standard, it is bidirectional and its structure is linked to a single central cable (CANbus) through which all instruments can send information, receive it and, if necessary, be powered. It is intended as a plug and play system, where each unit can be connected at any time making the system richer and at the same time simplifying the wiring. Data transmission takes place at 250 Kbps.

List of NMEA judgments

The following is a non-exhaustive list of the most used NMEA judgments, with a "free" translation into Italian. For official guidance, please refer to the NMEA website (the link is among the related items).

NMEA JudgmentOriginal DescriptionDescription EnglishObsolete
AAMWaypoint Arrival AlarmArrival alarm at waypoint
ALMGPS Almanac DataGPS almanac data
APAAutopilot Sentence?Autopilot sentences "A"X
APBAutopilot Sentence?Autopilot sentences "B"
ASDAutopilot System DataAutopilot system data
BECBearing and Distance to WaypointRoute and distance to waypoint
BODBearing - Waypoint to WaypointRoute waypoint to waypoint
BPIBearing and Distance to Point of InterestRoute and distance to a point of interestX
BWCBearing and distance to Waypoint - Great CircleOrthodromic course and distance to waypoint
BWRBearing and distance to Waypoint - Rhumb LineRoute and rhumb line distance to waypoint
DBKDepth Below KeelDepth under the keelX
DBSDepth Below SurfaceDepth below the surfaceX
DBTDepth below transducerDepth below the transducer
DCNDecca Position (obsolete)Position calculated from Decca signals
DRUDual Doppler Auxilary DataDual Doppler Auxiliary DataX
SDCDigital Selective Calling InformationDigital Selective Calling Information
DSEExtended DSCDSC Complete
ISDDSC Transponder InitiateInitialization of DSC call
DSRDSC Transponder ResponseResponse to DSC Initialization
DTMDatum ReferenceMap reference data
FSIFrequency Set InformationFrequency setting information
GBSGPS Satellite Fault DetectionGPS satellite error detection
GDADead Reckoning PositionEstimated recalculation positionX
GGAGlobal Positioning System Fix DataGPS position, time and position data
GLALoran C PositionsPosition Loran CX
GLCGeographic Position, Loran CTopographic map Loran C
GLLGeographic Position Latitude/LongitudeTopographic map Latitude/Longitude
GNSGNSS fixed dataGNSS position data
GOAOMEGA PositionsOmega positionX
GRSGNSS Range ResidualResidual deviation from GNSS position
GSAGPS DOP and active satellitesDilution of GPS accuracy and active satellites
GSTGNSS Pseudorange Error StatisticsGNSS axial error statistics
GSVSatellites in viewVisible satellites
GTDGeographic Location in Time DifferencesGeographical position in TD measureX
GXATRANSIT PositionsContesting position TRANSITX
HCCCompass HeadingRoute (Direction) compassX
HCDHeading and DeviationRoute and diversionX
HDGHeading Deviation and VariationCourse deviation and variations
HDMMagnetic HeadingMagnetic courseX
HDTHeading TrueTrue courseX
HSCHeading Steering CommandRoute correction command
HTCHeading TrueTrue Route
HVDMagnetic Variation, AutomaticMagnetic variation, automaticX
HVMMagnetic Variation, Manually SetMagnetic variation, set manuallyX
IMAVessel IdentificationVessel IdentifierX
LCDLoran C Signal DateLoran C signal data
MDAStandard Meteorological CompositeComposite Weather StandardX
MHUHumidityHumidity data (relative, apparent, dew)X
MMBBarometerBarometer data (bar and inch)X
MSKMSK Receiver Interface (for DGPS Beacon Receivers)MSK reception interface (for DGPS)
MSSMSK Receiver Signal StatusMSK signal reception status
MTAAir TemperaturesAir temperature in centigradeX
MTWWater TemperatureWater temperature
MWHWave HeightWave Height (meters and feet)X
MWDWind Direction and SpeedWind direction and speed
MWSWind and Sea StateWind conditions and waves in BeaufortX
MWVWind Speed and AngleWind speed and angle
OLNOmega Lane NumbersNumber of Omega linesX
OSDOwn Ship DataVarious current navigation data
RMARecommended Minimum Navigation Information LoranRecommended minimum navigation information
RMBRecommended Minimum Navigation Information GPSEssential data for reaching a waypoint
CTMRRecommended Minimum Navigation Information GPSEssential navigation data (position, speed, etc.)
RNNRoutesList of waypoints of a routeX
ROOWaypoints in active routeNumber of waypoints in the active route
ROTRate Of TurnRotation speed in degrees
RPMRevolutionsEngine speed
RSARudder Sensor AngleRudder bar sensor angle
RSDRADAR System DataRadar system data
SFIScanning Frequency InformationFrequency Scanning Information
SNULoran C SNR StatusReceiving status Loran C
STCTime ConstantTime constantX
STNMultiple Data IDData from multiple identifiers
STRTracking ReferenceDetection referencesX
SYSHybrid System ConfigurationHybrid system configurationX
TECTRANSIT Satellite Error Code and Doppler CountTRANSIT satellite error code and Doppler counter
TOETRANSIT Satellite Predicted ElevationExpected height of TRANSIT satellite
TGATRANSIT Satellite Antenna and Geoidal HeightsTRANSIT satellite antenna and geoidal height
TIFTRANSIT Satellite Initial FlagTRSAT satellite identifier
TLLTarget latitude and longitudeTarget latitude and longitude
TRFTRANSIT Fix Data (obsolete)TRANSIT position data
TRPTRANSIT Satellite Predicted Direction of RiseEstimated direction of TRANSAT satellite appearance
TRSTRANSIT Satellite Operating StatusTRANSIT satellite operating status
TTMTracked Target MessageTracking data against a target group
VBWDual Ground/Water SpeedLongitudinal speed and cross with respect to the ground
VDCCurrent at Selected DepthCurrent at a certain depth
VDRSet and DriftDirection and speed of travel
VHWWater speed and headingWater speed and course
VLWDistance Traveled through WaterDistance travelled on the water
VPESpeed, Dead Reckoning Parallel to True WindRecalculated speed parallel to the real wind
VPWSpeed Measured Parallel to WindMeasured speed parallel to the wind
ETAActual TrackCurrent track
VTGTrack made good and Ground speedCourse and speed with respect to the earth
VTIIntended TrackPlanned route
VWEWind Track EfficiencyWind efficiency on course
VWRRelative Wind Speed and AngleRelative wind speed and direction
VWTTrue Wind Speed and AngleTrue wind speed and direction
WCVWaypoint Closure VelocitySpeed of approach to waypoint
WDCDistance to Waypoint Great CircleDistance to waypoint on the great circle line
WDRDistance to Waypoint Rhumb LineDistance to waypoint on rhumb line
WFMRoute Following ModeHow to follow the route
WNCDistance Waypoint to WaypointDistance from waypoint to waypoint
WNRWaypoint To Waypoint Distance, Rhumb LineRhumb line distance from waypoint to waypoint
WPLWaypoint LocationWaypoint position
XDRTransducer MeasurementsTransducer measurements
XTECross Track Error, MeasuredOff course error, Measured
XTRCross Track Error Dead ReckoningOff course error, Recalculated
YWPWater Propagation SpeedSpeed of water propagation
YWSWater ProfileWater (including chemical) characteristics
ZAATimer, Elapsed/EstimatedElapsed/estimated time
ZDATime and Date UTC, day, month, year and local time zoneUTC Date & Time, Day, Month, Year and Time Zone
ZDLTime and Distance to Variable PointTime and distance from a variable point
ZEVEvent TimerEvent timer
ZFIElapsed Time from Point Of InterestTime spent from a point of interest
ZFOUTC and Time from origin WaypointUTC and Time from the source waypoint
ZLZTime of DayTime of day
ZPIArrival Time at Point Of InterestArrival time at point of interest
ZTAEstimated Time Of Arrival at WaypointEstimated time to get to the waypoint
ZTEEstimated Time to Even/Point Of InterestEstimated time to event / point of interest
ZTGUTC and Time to Destination WaypointUTC and time from arrival waypoint
ZTIEstimated Time to Even/Point Of InterestEstimated time to event / point of interest
ZWPArrival Time at WaypointArrival time at waypoint
ZZUTime, UTCUTC time