NMEA-0183 message: GNS

GNSS fix data

GNSS-capable receivers will always output this message with the GN talker ID.

GNSS-capable receivers will also output this message with other talker ID's when using more than one constellation for the position fix.

An example of the GNS message output from a GNSS-capable receiver is:

$GNGNS,014035.00,4332.69262,S,17235.48549,E,RR,13,0.9,25.63,11.24,,U,*70<CR><LF>

$GPGNS,014035.00,,,,,,8,,,,1.0,23*76<CR><LF>

$GLGNS,014035.00,,,,,,5,,,,1.0,23*67<CR><LF>

GNS message fields

Field

Meaning

0

Message ID $--GNS

Talker ID can be:
GA: Galileo
GB: BeiDou
GP: GPS
GL: GLONASS. When more than one constellation is used.
GN: Combined GNSS position, for example, GPS and GLONASS.
GQ: QZSS

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

Mode indicator:

  • Variable character field with one character for each supported constellation.

  • First character is for GPS.

  • Second character is for GLONASS.

  • Third character is Galileo.

  • Fourth character is for BeiDou.

  • Fifth character is for QZSS.

  • Subsequent characters will be added for new constellations.

Each character will be one of the following:

  • N = No fix. Satellite system not used in position fix, or fix not valid.

  • A = Autonomous. Satellite system used in non-differential mode in position fix.

  • D = Differential (including all OmniSTAR services). Satellite system used in differential mode in position fix.

  • P = Precise. Satellite system used in precision mode. Precision mode is defined as: no deliberate degradation (such as Selective Availability) and higher resolution code (P-code) is used to compute position fix.

  • R = Real-Time Kinematic. Satellite system used in RTK mode with fixed integers.

  • F = Float RTK. Satellite system used in real-time kinematic mode with floating integers.

  • E = Estimated (dead reckoning) mode.

  • M = Manual Input mode.

  • S = Simulator mode.

7

Number of SVs in use, range 00 to 99

8

HDOP calculated using all the satellites used in computing the solution reported in each GNS sentence.

9

Orthometric height in meters (MSL reference)

10

Geoidal separation in meters – The difference between the earth ellipsoid surface and mean-sea-level (geoid) surface defined by the reference datum used in the position solution.

“-” = mean-sea-level surface below ellipsoid.

11

Age of differential data – Null if talker ID is GN, additional GNS messages follow with Age of differential data.

12

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.

13

This field is added when the IEC61162-1:2010/NMEA 0183 V4.10 option is selected in the NMEA I/O Configuration page. It shows if a position is safe (S) or unsafe (U).

14

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 GNS 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 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), 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