NMEA-0183 message: GGA

Time, position, and fix related data

An example of the GGA message string is:

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

NOTE – The data string exceeds the NMEA standard length.

GGA message fields

Field

Meaning

0

Message ID $GPGGA

1

UTC of position fix

2

Latitude

3

Direction of latitude:

N: North
S: South

4

Longitude

5

Direction of longitude:

E: East
W: West

6

GPS Quality indicator:

0: Fix not valid
1: GPS fix
2: Differential GPS fix (DGNSS), SBAS, OmniSTAR VBS, Beacon, RTX in GVBS mode
3: Not applicable
4: RTK Fixed, xFill, RTX
5: RTK Float, OmniSTAR XP/HP, Location RTK, QZSS CLAS
6: INS Dead reckoning

7

Number of SVs in use, range from 00 through to 24+

8

HDOP

9

Orthometric height (MSL reference)

10

M: unit of measure for orthometric height is meters

11

Geoid separation

12

M: geoid separation measured in meters

13

Age of differential GPS data record, Type 1 or Type 9. Null field when DGPS is not used.

14

Reference station ID. A null field when any reference station ID is selected and no corrections are received. See table below for a description of the field values. When the position type is RTX, this field is replaced by the RTK position mode.

15

The checksum data, always begins with *

NOTE – If a user-defined geoid model, or an inclined plane is loaded into the receiver, then the height output in the NMEA GGA string is always the orthometric height (height above a geoid). The orthometric height is output even if no user-defined geoid is loaded (there is a simplified default geoid in the receiver), or if a user-defined geoid is loaded, or if an inclined plane is used.

When using one of the MSS (Mobile Satellite Services) OmniSTAR or Fugro, the Reference Station ID field indicates the following services:

Reference Station ID

Service

500 to 519

Authenticated G4

541 to 543

Authenticated G2

550 to 553

Authenticated G4+ (Galileo)

560 to 569

Authenticated G4+ (BeiDou)

591 to 593

Authenticated G2+ (GPS / GLONASS)

800 to 803

G4+ (Galileo)

810 to 819

G4+ (BeiDou)

841 to 843

G2+ (Position)

900 to 903

G4 (Galileo)

910 to 919

G4 (BeiDou)

1000 to 1002

HP (Position)

1008 to 1011

XP (Position)

1012 to 1015

G2 (Position)

1016 to 1018

HP/XP (Position)

1020 to 1022

HP G2 Position