Reference Information
LD900 Installation and Oper ations M anual
67
6.4.2 GGA Sentence
The NMEA GGA sentence contains time and position fix related data for a GPS system. It includes basic quality
information, which is limited to ‘Fix Quality’, ‘Number of Satellites in Use’, ‘HDOP’ and ‘Age of Corrections’.
GGA Sentence Structure & Example
$GPGGA, hhmmss.ss, ddmm.mmmmm, a, dddmm.mmmmm, b, q, xx, p.p, a.b, M, c.d, M, x.x, nnnn *hh
$GPGGA, 123519.00,
4807.03787, N,
01131.00547, E, 1, 15, 0.9, 545.4, M, 46.9, M, 14.0, 0281 *47
GGA Sentence Defined
Field
Content
GGA
Global positioning system fix data
hhmmss.ss
UTC of position
ddmm.mmmmm
Latitude of position
a
N or S, latitude hemisphere
dddmm.mmmmm
Longitude of position
b
E or W, longitude hemisphere
q
GPS Quality indicator (0 = invalid, 1 = GPS SPS, 2 = DG NSS fix, 4 = Fixed RTK, 5 =
Float RTK / PPP, 6 = Dead Reckoning), 7 = Manual Input Mode, 8 = Simulation Mode
xx
Number of satellites in use
p.p
HDOP (Horizontal dilution of precision)
a.b
Antenna altitude above/below mean-sea-level
M
Units of antenna altitude, meters
c.d
The relationship between the geoid and the WGS84 ellipsoid
M
Units of meters
x.x
Age of corrections
nnnn
Differential reference station ID, 0000 to 1023
*hh
Checksum
[CR][LF]
Sentence Terminator
NOTE
The number of decimal places in the GGA message Latitude and Longitude values is configurable, see
sections relating to
COM
or
ICOM
GGA precision where required. If making changes from 5 decimal places
the sentence will no longer conform with NMEA v3.01.
