NMEA Commands 269
NMEA Commands
Table 8.42 outlines the message format.
Typical RMC message:
$GPRMC,213357.20,A,3722.410857,N,12159.773686,W,000.3,102.4,290
498,15.4,W*43
Table 8.42. $GPRMC Message Format
Parameter Description Range
m1 UTC time of the position fix (hhmmss.ss) 000000.00 to 235959.95
c2 Status of the position fix (always A)
• A—Autonomous, position data is valid
• D—Differential, position data valid
• V—Invalid for all values of the Indicator mode
A, D, V
m3 Latitude (ddmm.mmmmmm) 0000.000000° to
8959.999999°
c4 Latitude sector N—North
S—South
m5 Longitude (dddmm.mmmmmm) 00000.000000° to
17959.999999°
c6 Longitude sector E—East
W—West
f7 Speed over the ground (knots) 000.0 to 999.9
f8 Course over the ground (degrees); referenced to true north 000.0° to 359.9°
d9 Date (ddmmyy) 010100 to 123199
f10 Magnetic variation (degrees) 0.0° to 99.9°
c11 Direction of magnetic variation:
• Easterly variation - subtract this value from true north
course
• Westerly variation - add this value to true north course
E—East
W—West
d12 Positioning system mode indicator
• A—Autonomous mode
• D—Differential mode
• E—Estimated (dead reckoning) mode
• M—Manual input mode
• S—Simulator mode
• N—Data not valid
The positioning system mode indicator field supplements
the positioning system for the Status field.
A, D, E, M, S, or N
*hh The hexadecimal checksum is computed by exclusive -
ORing all of the bytes in the message between, but not
including, the $and the *. The result is *hh where h is a hex
character.
0 to 9 and A through F
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