GPGGA

GPS fix data and undulation

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

This log contains time, position and fix related data of the GNSS receiver. See also Table: Position Precision of NMEA Logs.

The GPGGA log outputs these messages without waiting for a valid almanac. Instead, it uses a UTC time, calculated with default parameters. In this case, the UTC time status (see the TIME log) is set to WARNING since it may not be one hundred percent accurate. When a valid almanac is available, the receiver uses the real parameters. Then the UTC time status is set to VALID.

The GPGGA log can be customized using the NMEAFORMAT command.

The position for the GPGGA log is reported in the user selected datum. See the DATUM command for more details.

When the solution type is INS (SPAN models), the DOPs in the GPGGA log are calculated at a 1 Hz rate.
To determine if the receiver is providing an INS solution, check the pos type field in the BESTPOS log.

Message ID: 218

Log Type: Synch

Recommended Input:

log gpgga ontime 1

Example:

$GPGGA,202530.00,5109.0262,N,11401.8407,W,5,40,0.5,1097.36,M,-17.00,M,18,TSTR*61

 

The NMEA (National Marine Electronics Association) has defined standards that specify how electronic equipment for marine users communicate. GNSS receivers are part of this standard and the NMEA has defined the format for several GNSS data logs otherwise known as 'sentences'.

Each NMEA sentence begins with a '$' followed by a two-letter prefix identifying the type of sending device (for example 'GP', 'GL' or ‘GN’), followed by a sequence of letters that define the type of information contained in the sentence. Data contained within the sentence is separated by commas and the sentence is terminated with a two digit checksum followed by a carriage return/line feed. Here is an example of a NMEA sentence describing time, position and fix related data:

$GPGGA,134658.00,5106.9792,N,11402.3003,W,2,09,1.0,1048.47,M,
-16.27,M,08,AAAA*60

The GPGGA sentence shown above and other NMEA logs are output the same no matter what GNSS receiver is used, providing a standard way to communicate and process GNSS information. For more information about NMEA, see the NMEATALKER command.

Field

Structure

Description

Symbol

Example

1

$GPGGA

Log header

 

$GPGGA

2

utc

UTC time status of position (hours/minutes/seconds/ decimal seconds)

hhmmss.ss

202134.00

3

lat

Latitude (DDmm.mm)

llll.ll

5106.9847

4

lat dir

Latitude direction (N = North, S = South)

a

N

5

lon

Longitude (DDDmm.mm)

yyyyy.yy

11402.2986

6

lon dir

Longitude direction (E = East, W = West)

a

W

7

quality

refer to Table: GPS Quality Indicators

x

1

8

# sats

Number of satellites in use. May be different to the number in view

xx

10

9

hdop

Horizontal dilution of precision

x.x

1.0

10

alt

Antenna altitude above/below mean sea level

x.x

1062.22

11

a-units

Units of antenna altitude (M = metres)

M

M

12

undulation

Undulation - the relationship between the geoid and the WGS84 ellipsoid

x.x

-16.271

13

u-units

Units of undulation (M = metres)

M

M

14

age

Age of correction data (in seconds)

The maximum age reported here is limited to 99 seconds.

xx

(empty when no differential data is present)

15

stn ID

Differential base station ID

xxxx

(empty when no differential data is present)

16

*xx

Check sum

*hh

*48

17

[CR][LF]

Sentence terminator

 

[CR][LF]
GPS Quality Indicators

Indicator

Description

0

Fix not available or invalid

1

Single point

Converging PPP (TerraStar-L)

2

Pseudorange differential

Converged PPP (TerraStar-L)

Converging PPP (TerraStar-C, TerraStar-C PRO, TerraStar-X)

4

RTK fixed ambiguity solution

5

RTK floating ambiguity solution

Converged PPP (TerraStar-C, TerraStar-C PRO, TerraStar-X)

6

Dead reckoning mode

7

Manual input mode (fixed position)

8

Simulator mode

9

WAAS (SBAS)1

Refer to the BESTPOS log and Table: Supplemental Position Types and NMEA Equivalents.