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Null fields
☞
☞
A.3
Syntax
Description of fields
NMEA Message Formats
Symbol
Field
No symbol
Informa-
tion
unavailable
for output
Fields are always separated by a comma. Before the Checksum field there is
never a comma.
When information for a field is not available, the position in the data string is
empty.
GGA - Global Positioning System Fix Data
$--GGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh<CR><LF>
Field
Description
$--GGA
Header including Talker ID
hhmmss.ss
UTC time of position
llll.ll
Latitude (WGS 1984)
a
Hemisphere, North or South
yyyyy.yy
Longitude (WGS 1984)
a
East or West
x
Position quality indicator
0 = Fix not available or invalid
1 = No real-time position, navigation fix
2 = Real-time position, ambiguities not fixed
3 = Valid fix for GNSS Precise Positioning Service mode, for
example WAAS
4 = Real-time position, ambiguities fixed
xx
Number of satellites in use. For $GNGGA messages: The
combined GPS, GLONASS, Galileo and BeiDou satellites used
in the position.
x.x
HDOP
x.x
Altitude of position marker above/below mean sea level in
metres. If no orthometric height is available the local ellips-
oidal height will be exported. If the local ellipsoidal height is
not available either, the WGS 1984 ellipsoidal height will be
exported.
M
Units of altitude as fixed text M
x.x
Geoidal separation in metres. The Geoidal separation is the
difference between the WGS 1984 earth ellipsoid surface
and mean sea level.
M
Units of geoidal separation as fixed text M
x.x
Age of differential GNSS data, empty when DGPS not used
xxxx
Differential base station ID, 0000 to 1023
Description
Null fields do not contain any
information.
Example
,,
61
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