NMEA-0183 messages: Common message elements

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Each message contains:

  • a message ID consisting of $GP followed by the message type. For example, the message ID of the GGA message is $GPGGA.
  • a comma.
  • a number of fields, depending on the message type, separated by commas.
  • an asterisk.
  • a checksum value.

The following example shows a simple message with a message ID ($GPGGA), followed by 13 fields and a checksum value:

$GPGGA,172814.0,3723.46587704,N,12202.26957864,W,2,6,1.2,18.893,M,-25.669,M,2.0,0031*4F

NMEA Message values

NMEA messages that the receiver generates contains the following values:

Value Description
Latitude and Longitude Latitude is represented as ddmm.mmmm and longitude is represented as dddmm.mmmm, where:
  • dd or ddd is degrees
  • mm.mmmm is minutes and decimal fractions of minutes
Direction Direction (north, south, east, or west) is represented by a single character: N , S , E , or W.
Time Time values are presented in Universal Time Coordinated (UTC) and are represented as hhmmss.ss, where:
  • hh is hours, from 00 through 23
  • mm is minutes
  • ss.ss is seconds with variable length decimal-fraction of seconds