Introduction

NMEA - National Marine Electronics Association

Sentences

Basic Structure

Sentences start with a leading dollar sign ($) and end with a carriage return/line feed. There is often an asterisk (*) followed by an exclusive OR checksum. Sentence length can be no longer than 80 characters, excluding closing characters.

AAM

Waypoint Arrival Alarm

ALM

Almanac data

APA

Auto Pilot A sentence

APB

Auto Pilot B sentence

BOD

Bearing Origin to Destination

BWC

Bearing using Great Circle route

DTM

Datum being used.

GGA

Fix information

GLL

Lat/Lon data

GRS

GPS Range Residuals

GSA

Overall Satellite data

GST

GPS Pseudorange Noise Statistics

GSV

Detailed Satellite data

MSK

send control for a beacon receiver

MSS

Beacon receiver status information.

RMA

recommended Loran data

RMB

recommended navigation data for gps

RMC

Recommended Minimum Data for GPS

This is the most commonly used NMEA Sentence. This provides the basic information of Location, Velocity, and Time.

Structure:

$GPRMC,<TIME>,<STS>,<LATITUDE>,<LAT_BEARING>,<LONG ITUDE>,<LON_BEARING>,<SPEED>,<TRACK>,<DATE>,<MAG_V AR>,<MAG_VAR_DIR>*<CHECKSUM>

Definition:
  • $GPRMC - Header
  • <TIME> - Time in HHMMSS format. Zero-filled.
  • <STS> - Status

    • A - Active
    • V - Void
  • <LATITUDE> - Latitude in DDMM.SSSS (Degrees, Minutes, Seconds) format. Zero-Filled.
  • <LAT_BEARING>

    • N - North
    • S - South
  • <LONGITUDE> - Longitude in DDMM.SSSS (Degrees, Minutes, Seconds) format. Zero-Filled.
  • <LON_BEARING>

    • E - East
    • W - West
  • <SPEED> - Speed given in knots in 000.0 format. Zero-filled.
  • <TRACK> - Track angle in degrees true
  • <DATE> - Date given in DDMMYY format
  • <MAG_VAR> - Magnetic Variation
  • <MAG_VAR_DIR> - Direction of Magnetic Variation
  • *<CHECKSUM> - XOR CheckSum


RTE

route message

TRF

Transit Fix Data

STN

Multiple Data ID

VBW

dual Ground / Water Spped

VTG

Vector track an Speed over the Ground

WCV

Waypoint closure velocity (Velocity Made Good)

WPL

Waypoint Location information

XTC

cross track error

XTE

measured cross track error

ZTG

Zulu (UTC) time and time to go (to destination)

ZDA

Date and Time

Sources/References

http://www.gpsinformation.org/dale/nmea.htm
http://aprs.gids.nl/nmea/