Using the External Computer Data Link
MicronNav System
0656-SOM-00001-07
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7.2.7. NMEA $GPGGA
This NMEA string format is used for Global Positioning and mainly sent by GPS devices. It
is a common format for providing co-ordinate positions in Latitude / Longitude format. There
are a number of fields in this string that are not applicable and these fields have been set
to sensible values as default.
The full string format is as follows:
‘$GPGGA’ Reply Data Structure
Data Description
Data Range
Field Range
NMEA string header
Always ‘$GPGGA’
hhhhhh
Comma separator
Always ‘,’
,
Time of data, UTC = hhmmss.ss
000000.00 to 235959.99
hhmmss.ss
Comma separator
Always ‘,’
,
Latitude of Target in Deg Min
(Only valid when Compass and GPS input
data are valid)
0 to 90 Degs
DDMM.SSSS
Comma separator
Always ‘,’
,
Latitude N or S
‘N’ or ‘S’
a
Comma separator
Always ‘,’
,
Longitude of Target in Deg Min
(Only valid when Compass and GPS input
data are valid)
0 to 180 Degs
DDDMM.SSSS
Comma separator
Always ‘,’
,
Longitude E or W
‘E’ or ‘W’
a
Comma separator
Always ‘,’
,
GPS Quality Indicator
Always 2 (DGPS)
x
Comma separator
Always ‘,’
,
Number of Satellites in Use
Always 7 (N/A)
xx
Comma separator
Always ‘,’
,
HDOP
Always 2.2
x.x
Comma separator
Always ‘,’
,
Antenna Altitude
Always 0.0
x.x
Comma separator
Always ‘,’
,
Altitude Units Identifier
‘M’ for metres
a
Comma separator
Always ‘,’
,
Geoidal Separation
Always 0.0
x.x
Comma separator
Always ‘,’
,
Units Identifier
‘M’ for metres
a
Comma separator
Always ‘,’
,
Age of Differential GPS data
Always 1.2
x.x
Comma separator
Always ‘,’
,
Differential Reference Station ID
Always 1234
xxxx
Comma separator
Always ‘,’
,
Delimiter (asterisk)
Always ‘*’
*