常用NMEA0183的报文解析

Message     Function
  ADV     Position and satellite information for RTK network operations
  DTM     Datum reference information
  GBS     GNSS satellite fault detection (RAIM support)
  GGA     Time, position, and fix related data
  GLL     Position data: position fix, time of position fix, and status
  GNS     GNS Fix data
  GRS     GRS range residuals
  GSA     GPS DOP and active satellites
  GST     Position error statistics
  GSV     Number of SVs in view, PRN, elevation, azimuth, and SNR
  HDT     Heading from True North
  LLQ     Leica local position and quality
  PFUGDP     A proprietary message containing information about the type of positioning system, position, number of satellites and position statistics
  PTNL,AVR     Time, yaw, tilt, range, mode, PDOP, and number of SVs for Moving Baseline RTK
  PTNL,BPQ     Base station position and position quality indicator
  PTNL,DG     L-band corrections and beacon signal strength and related information
  PTNL,GGK     Time, position, position type, and DOP values
  PTNL,PJK     Time, position, position type, and DOP values
  PTNL,PJT     Projection type
  PTNL,VGK     Time, locator vector, type, and DOP values
  PTNL,VHD     Heading Information
  RMC     Position, Velocity, and Time
  ROT     Rate of turn
  VTG     Actual track made good and speed over ground
  ZDA     UTC day, month, and year, and local time zone offset
  ##########
  1. AVD
  Position and satellite information for RTK network operations

The messages alternate between subtype 110 and 120.
  ADV subtype 110 message fields

An example of the ADV subtype 110 message string is:

$PGPPADV,110,39.88113582,-105.07838455,1614.125*1M
  Field     Meaning
  0     Message ID $PGPPADV
 1     Message subtype 110
  2     Latitude
  3     Longitude
  4     Ellipsoid height
  6     Elevation of second satellite, in degrees, 90° maximum
  7     Azimuth of second satellite, degrees from True North, 000° through 359°
  8     The checksum data, always begins with *
  ADV subtype 120 message fields

An example of the ADV subtype 120 message string is:

$PGPPADV,120,21,76.82,68.51,29,20.66,317.47,28,52.38,276.81,22,42.26,198.96*5D

Field     Meaning
 0     Message ID $PGPPADV
  1     Message subtype 120
  2     First SV PRN number
  3     Elevation of first satellite, in degrees, 90° maximum
  4     Azimuth of first satellite, degrees from True North, 000° through 359°
  5     Second SV PRN number
  6     Elevation of second satellite, in degrees, 90° maximum
  7     Azimuth of second satellite, degrees from True North, 000° through 359°
  8     The checksum data, always begins with *
  ########
  2. DTM
  Datum reference information

The DTM message string identifies the datum used. An example of the GPDTM message string is:

$GPDTM,xxx,x,xx.xxxx,x,xx.xxxx,x,,xxx*hh<CR><LF>


 DTM message fields


 Field     Meaning
  1     Local datum code (xxx):
        W84 – WGS84
        W72 – WGS72
        S85 – SGS85
        P90 – PE90
        999 – User defined
        IHO datum code
  2     Local datum sub code (x)
  3     Latitude offset in minutes (xx.xxxx)
  4     Latitude offset mark (N: +, S: -) (x)
  5     Longitude offset in minutes (xx.xxxx)
  6     Longitude offset mark (E: +, W: -) (x)
  7     Altitude offset in meters. Always null
  8     Datum (xxx):
        W84 – WGS84
        W72 – WGS72
        S85 – SGS85
        P90 – PE90
        999 – User defined
        IHO datum code
  9     Checksum
  #########
  3. GBS
  GNSS satellite fault detection (RAIM support)

An example of the GBS message string is:

$GPGBS,015509.00,-0.031,-0.186,0.219,19,0.000,-0.354,6.972*4D
  GBS message fields
  Field     Meaning
  0     Message ID $--GBS
  1     UTC of position fix
  2     Expected error in latitude, in meters, due to bias, with noise = 0
  3     Expected error in longitute, in meters, due to bias, with noise = 0
  4     Expected error in altitude, in meters, due to bias, with noise = 0
  5     ID number of most likely failed satellite
  6     Probability of missed detection of most likely failed satellite
  7     Estimate of bias, in meters, on the most likely failed satellite
  8     Standard deviation of bias estimate
 9     The checksum data, always begins with *
  ########
  4. GGA
  Time, position, and fix related data

An example of the GBS 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, OmniSTAR VBS
      4: Real-Time Kinematic, fixed integers
      5: Real-Time Kinematic, float integers, OmniSTAR XP/HP or Location RTK
 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, range 0000-4095. A null field when any reference station ID is selected and no corrections are received1.
  15     The checksum data, always begins with *
  ###########
  5. GLL
  Position data: position fix, time of position fix, and status

An example of the GLL message string is:

$GPGSA,A,3,3,6,27,19,9,14,21,22,18,15,,,2.1,1.0,1.8*03
  GLL message fields
 Field     Meaning
  0     Message ID $GPGLL
 1     Latitude in dd mm,mmmm format (0-7 decimal places)
  2     Direction of latitude N: North S: South
  3     Longitude in ddd mm,mmmm format (0-7 decimal places)
  4     Direction of longitude E: East W: West
  5     UTC of position in hhmmss.ss format
  6     Fixed text "A" shows that data is valid
  7     The checksum data, always begins with *
  #########
  6. 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 the GP and/or GL talker ID 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,,*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:

   GP: To provide information specific to the GPS constellation when more than one constellation is used for the differential position fix
     GL: To provide information specific to the GLONASS constellation when more than one constellation is used for the differential position fix
     GN: GNSS position fix from more than one constellation (eg. GPS + GLONASS)
  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
          Subsequent characters will be added for new constellation

        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 00–99
  8     HDOP calculated using all the satellites (GPS, GLONASS, and any future 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 GP and/or GL Age of differential data
  12     Reference station ID(When using OmniSTAR services, the Reference Station ID indicates the following services: VBS 100=VBS; 1000=HP; 1001 = HP/    XP (Orbits) ; 1002 = HP/G2 (Orbits); 1008 = XP (GPS); 1012 = G2 (GPS); 1013 = G2 (GPS/GLONASS); 1014 = G2 (GLONASS); 1016 = HP/XP (GPS); 1020 = HP/G2 (GPS) ; 1021 = HP/G2 (GPS/GLONASS). ), range 0000-4095
          - Null if talker ID is GN, additional GNS messages follow with GP and/or GL Reference station ID
  13     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 simplified default geoid in the receiver), or if a user-defined geoid is loaded, or if an inclined plane is used.
  ##############
  7. GRS
  GRS range residuals

The GRS message is used to support the Receiver Autonomous Integrity Monitoring (RAIM).

Note – Because the contents of this NMEA message do not change significantly during a one-second interval, the receiver outputs this message at a maximum rate of 1 Hz.

An example of the GRS message string is:

$GPGRS,220320.0,0,-0.8,-0.2,-0.1, -0.2,0.8,0.6,,,,,,,*55
  GRS message fields
  Field     Meaning
  0     Message ID $GPGRS
  1     UTC of GGA position fix
  2     Residuals
         0: Residuals used to calculate position given in the matching GGA line
         1: Residuals recomputed after the GGA position was computed
         3–14     Range residuals for satellites used in the navigation solution, in meters
  #############
  8.GSA
  GPS DOP and active satellites

An example of the GSA message string is:

$GPGSA,<1>,<2>,<3>,<3>,,,,,<3>,<3>,<3>,<4>,<5>,<6>*<7><CR><LF>
  GSA message fields
  Field     Meaning
  0     Message ID $GPGSA
  1     Mode 1, M = manual, A = automatic
  2     Mode 2, Fix type, 1 = not available, 2 = 2D, 3 = 3D
  3     PRN number, 01 through 32 for GPS, 33 through 64 for SBAS, 64+ for GLONASS
  4     PDOP: 0.5 through 99.9
  5     HDOP: 0.5 through 99.9
  6     VDOP: 0.5 through 99.9
  7     The checksum data, always begins with *
  ############
  9.GST
  Position error statistics

An example of the GST message string is:

$GPGST,172814.0,0.006,0.023,0.020,273.6,0.023,0.020,0.031*6A

The Talker ID ($--) will vary depending on the satellite system used for the position solution:

    $GP - GPS only
      $GL - GLONASS only
      $GN - Combined

GST message fields
  Field     Meaning
  0     Message ID $GPGST
  1     UTC of position fix
  2     RMS value of the pseudorange residuals; includes carrier phase residuals during periods of RTK (float) and RTK (fixed) processing
  3     Error ellipse semi-major axis 1 sigma error, in meters
  4     Error ellipse semi-minor axis 1 sigma error, in meters
  5     Error ellipse orientation, degrees from true north
  6     Latitude 1 sigma error, in meters
  7     Longitude 1 sigma error, in meters
  8     Height 1 sigma error, in meters
  9     The checksum data, always begins with *
  ###############
  10. GSV
  Satellite information

The GSV message string identifies the number of SVs in view, the PRN numbers, elevations, azimuths, and SNR values. An example of the GSV message string is:

$GPGSV,4,1,13,02,02,213,,03,-3,000,,11,00,121,,14,13,172,05*67
  GSV message fields
  Field     Meaning
  0     Message ID $GPGSV
  1     Total number of messages of this type in this cycle
  2     Message number
  3     Total number of SVs visible
  4     SV PRN number
  5     Elevation, in degrees, 90° maximum
  6     Azimuth, degrees from True North, 000° through 359°
  7     SNR, 00 through 99 dB (null when not tracking)
  8–11     Information about second SV, same format as fields 4 through 7
  12–15     Information about third SV, same format as fields 4 through 7
  16–19     Information about fourth SV, same format as fields 4 through 7
  20     The checksum data, always begins with *
  #############
  11. HDT
  Heading from True North

An example of the HDT string is:

$GPHDT,123.456,T*00
  Heading from true north message fields
  Field     Meaning
  0     Message ID $GPHDT
  1     Heading in degrees
  2     T: Indicates heading relative to True North
  3     The checksum data, always begins with *
  ###########
  12. LLQ

Leica local position and quality
  Field     Meaning
  0     Message ID $GPLLQ
  1     hhmmss.ss - UTC time of position
  2     ddmmyy - UTC date
  3     xxx.xxx - Grid easting (meters)
  4     M - Meter, fixed text
  5     xxxx.xxxx - Grid northing (meters)
  6     M - Meter, fixed text
  7     x - GPS quality. 0 = not valid. 1 = GPS Nav Fix. 2 = DGPS Fix. 3 = RTK Fix.
  8     x - Number of satellites used in computation
 9     xx.xx - Position quality (meters)
  10     xxxx.xxxx - Height (meters)
  11     M - Meter, fixed text
           *hh - checksum
           <CR> - carriage return
           <LF> - Line feed
 ########
  13. PFUGDP
  Proprietary Fugro positioning message

The PFUGDP message is a proprietary message containing information about the type of positioning system, position, number of satellites and position statistics.

An example of the PFUGDP message string is:

$PFUGDP,GP,hhmmss.ss,ddmm.mmmmm,D,dddmm.mmmmm,D,sv,QI,DD,It,In,dir,ht*XX
  PFUGDP message fields
  Field     Meaning
  1     Type of positioning system (GP = GPS, GL = GLONASS, GN = GNSS)
  2     UTC of position fix
  3–4     Latitude in DDMM,MMMMM format, N (North) or S (South)
  5–6     Latitude in DDMM,MMMMM format, E (East) or W (West)
  7     Number of satellites in use
  8     DPVOA (UKOOA) quality indicator (0–9)
  9     DGNSS mode indicator (as defined for NMEA standard telegram $_GNS)
  10     Error ellipse standard deviation semi-major axis, in meters
  11     Error ellipse standard deviation semi-minor axis, in meters
  12     Direction of the semi-major axis of the error ellipse, in degrees
  13     RMS value of the standard deviation of the range inputs to the navigation process
  ##########
  14. PTNL,AVR
  Time, yaw, tilt, range for moving baseline RTK

An example of the PTNL,AVR message string is:

$PTNL,AVR,181059.6,+149.4688,Yaw,+0.0134,Tilt,,,60.191,3,2.5,6*00
  AVR message fields
  Field     Meaning
  0     Message ID $PTNL,AVR
  1     UTC of vector fix
  2     Yaw angle in degrees
  3     Yaw
  4     Tilt angle in degrees
  5     Tilt
  6     Reserved
  7     Reserved
  8     Range in meters
  9     GPS quality indicator:
         0: Fix not available or invalid
         1: Autonomous GPS fix
         2: Differential carrier phase solution RTK (Float)
         3: Differential carrier phase solution RTK (Fix)
         4: Differential code-based solution, DGPS
  10     PDOP
  11     Number of satellites used in solution
 12     The checksum data, always begins with *
  ###########
  15. PTNL,BPQ
  Base station position and quality indicator

This message describes the base station position and its quality. It is used when the moving base antenna position and quality are required on one serial port (along with a heading message) from a receiver in heading mode, typically the SPSx61.

An example of the PTNL,BPQ message string is:

$PTNL,BPQ,224445.06,021207,3723.09383914,N,12200.32620132,W,EHT-5.923,M,5*
  BPQ message fields
  Field     Meaning
  0     Talker ID
  1     BPQ
  2     UTC time of position fix, in hhmmss.ss format. Hours must be two numbers, so may be padded, for example, 7 is shown as 07.
  3     UTC date of position fix, in ddmmyy format. Day must be two numbers, so may be padded, for example, 8 is shown as 08.
  4     Latitude, in degrees and decimal minutes (ddmm.mmmmmmm)
  5     Direction of latitude:
         N: North
         S: South
  6     Longitude, in degrees and decimal minutes (dddmm.mmmmmmm). Should contain 3 digits of ddd.
  7     Direction of longitude:
         E: East
         W: West
  8     Height Ellipsoidal height of fix (antenna height above ellipsoid). Must start with EHT.
  9     M: ellipsoidal height is measured in meters
  10     GPS quality indicator:
          0: Fix not available or invalid
          1: Autonomous GPS fix
          2: Differential SBAS, or OmniSTAR VBS
          4: RTK Fixed
          5: OmniSTAR XP, OmniSTAR HP, Float RTK, or Location RTK
  11     The checksum data, always begins with *
  ##########
  16. PTNL,DG
  L-band corrections and beacon signal strength and related information

This message, $PTNLDG, is a Trimble-created message. It outputs the L-band and beacon signal strength and other information.

Examples of the PTNL,DG message string are:

For beacon DG message: $PTNLDG,44.0,33.0,287.0,100,0,4,1,0,,,*3E

For L-band DG message: $PTNLDG,124.0,10.5,1557855.0,1200,2,4,0,3,,,*3C
  DG message fields
  Field     Meaning
  0     Talker ID
 1     Signal strength
  2     SNR in db
  3     Signal frequency in kHz
  4     Bit rate
  5     Channel number. For a beacon message, the system locks only to the primary channel. As a result, there is not more than one beacon message. The     channel for beacon is 0 (so it matches the DSM 232 family of GPS receivers). For L-band messages, the channel number is 2 (so it matches the         DSM 232 family of GPS receivers).
  6     Tracking status:
         0: Channel idle.
         1: Wideband FFT search.
         2: Searching for signal.
         3: Channel has acquired signal.
         4: Channel has locked onto signal. For beacon, this means valid RTCM has been received. For L-band, this means good data has been decoded.
         5: Channel disabled.
  7     Channel used. Output 1 if the RTCM is being used for outputting DGPS position. 0 otherwise. If the system is not outputting DGPS, the output is     0 also.
  8     Channel tracking performance indicator. For beacon this is the word error rate, which is in percentage. For L-band, this is the time since the last sync, in tenths of seconds ranging from 0 through 255.
  #############
  17. PTNL,GGK
  Time, position, position type, DOP

An example of the PTNL,GGK message string is:

$PTNL,GGK,102939.00,051910,5000.97323841,N,00827.62010742,E,5,09,1.9,EHT150.790,M*73
  PTNL,GGK message fields
  Field     Meaning
  0     Talker ID $PTNL
  1     Message ID GGK
  2     UTC time of position fix, in hhmmmss.ss format. Hours must be two numbers, so may be padded. For example, 7 is shown as 07.
  3     UTC date of position fix, in ddmmyy format. Day must be two numbers, so may be padded. For example, 8 is shown as 08.
  4     Latitude, in degrees and decimal minutes (dddmm.mmmmmmm)
  5     Direction of latitude:
         N: North
         S: South
  6     Longitude, in degrees and decimal minutes (dddmm.mmmmmmm). Should contain three digits of ddd.
  7     Direction of longitude:
         E: East
         W: West
  8     GPS Quality indicator:
         0: Fix not available or invalid
         1: Autonomous GPS fix
         2: RTK float solution
         3: RTK fix solution
         4: Differential, code phase only solution (DGPS)
         5: SBAS solution – WAAS/EGNOS/MSAS
         6: RTK float or RTK location 3D Network solution
         7: RTK fixed 3D Network solution
         8: RTK float or RTK location 2D in a Network solution
         9: RTK fixed 2D Network solution
         10: OmniSTAR HP/XP solution
         11: OmniSTAR VBS solution
         12: Location RTK solution
         13: Beacon DGPS
  9     Number of satellites in fix
  10     Dilution of Precision of fix (DOP)
  11     Ellipsoidal height of fix (antenna height above ellipsoid). Must start with EHT.
  12     M: ellipsoidal height is measured in meters
  13     The checksum data, always begins with *

Note – The PTNL,GGK message is longer than the NMEA-0183 standard of 80 characters.

Note – Even if a user-defined geoid model, or an inclined plane is loaded into the receiver, then the height output in the NMEA GGK string is always an ellipsoid height, for example, EHT24.123.
  ################
  18. PTNL,PJK
  Local coordinate position output

Some examples of the PTNL,PJK message string are:

$PTNL,PJK,202831.50,011112,+805083.350,N,+388997.346,E,10,09,1.5,GHT+25.478,M*77

$PTNL,PJK,010717.00,081796,+732646.511,N,+1731051.091,E,1,05,2.7,EHT+28.345,M*7C
  PTNL,PJK message fields
  Field     Meaning
  0     Message ID $PTNL,PJK
  1     UTC of position fix
  2     Date
  3     Northing, in meters
  4     Direction of Northing will always be N (North)
  5     Easting, in meters
  6     Direction of Easting will always be E (East)
  7     GPS Quality indicator:
         0: Fix not available or invalid
        1: Autonomous GPS fix
         2: RTK float solution
         3: RTK fix solution
         4: Differential, code phase only solution (DGPS)
         5: SBAS solution – WAAS/EGNOS/MSAS
         6: RTK Float 3D network solution
         7: RTK Fixed 3D network solution
         8: RTK Float 2D network solution
         9: RTK Fixed 2D network solution
         10: OmniSTAR HP/XP solution
         11: OmniSTAR VBS solution
         12: Location RTK
         13: Beacon DGPS
  8     Number of satellites in fix
  9     DOP of fix
  10     Height of Antenna Phase Center (see Note below)
  11     M: height is measured in meters
  12     The checksum data, always begins with *

Note – The PTNL,PJK message is longer than the NMEA-0183 standard of 80 characters.

Note – If a user-defined geoid model, or an inclined plane is loaded into the receiver, then the NMEA PJK string will always report the orthometric height (the field starts with the letters GHT). If the latitude/longitude of the receiver is outside the user-defined geoid model bounds, then the height is shown as ellipsoidal height (the field starts with the letters EHT).

Note – If the receiver does not have an application file, this string returns nothing in fields 3, 4, 5, 6, or 10.
  ##################
  19. PTNL,PJT
  Projection type

An example of the PTNL,PJT message string is:

$PTNL,PJT,NAD83(Conus),California Zone 4 0404,*51
  PTNL,PJT message fields
  Field     Meaning
  0     Message ID $PTNL,PJT
  1     Coordinate system name (can include multiple words)
  2     Project name (can include multiple words)
  3     The checksum data, always begins with *

#################
  20. PTNL,VGK
  Vector information

An example of the PTNL,VGK message string is:

$PTNL,VGK,160159.00,010997,-0000.161,00009.985,-0000.002,3,07,1,4,M*0B
  PTNL,VGK message fields
  Field     Meaning
  0     Message ID $PTNL,VGK
 1     UTC of vector in hhmmss.ss format
  2     Date in mmddyy format
  3     East component of vector, in meters
  4     North component of vector, in meters
  5     Up component of vector, in meters
  6     GPS Quality indicator:
         0: Fix not available or invalid
         1: Autonomous GPS fix
         2: RTK float solution
         3: RTK fix solution
         4: Differential, code phase only solution (DGPS)
         5: SBAS solution – WAAS/EGNOS/MSAS
         6: RTK Float 3D network solution
         7: RTK Fixed 3D network solution
         8: RTK Float 2D network solution
         9: RTK Fixed 2D network solution
         10: OmniSTAR HP/XP solution
         11: OmniSTAR VBS solution
         12: Location RTK
         13: Beacon DGPS
  7     Number of satellites if fix solution
  8     DOP of fix
  9     M: Vector components are in meters
  10     The checksum data, always begins with *
  #############
  21. PTNL,VHD
  Heading information

An example of the PTNL,VHD message string is:

$PTNL,VHD,030556.00,093098,187.718,-22.138,-76.929,-5.015,0.033,0.006,3,07,2.4,M*22
  PTNL,VHD message fields
  Field     Meaning
  0     Message ID $PTNL,VHD
  1     UTC of position in hhmmss.ss format
  2     Date in mmddyy format
  3     Azimuth
  4     Azimuth/Time
  5     Vertical Angle
  6     Vertical/Time
  7     Range
  8     Range/Time
  9     GPS Quality indicator:
         0: Fix not available or invalid
         1: Autonomous GPS fix
         2: RTK float solution
         3: RTK fix solution
         4: Differential, code phase only solution (DGPS)
         5: SBAS solution – WAAS/EGNOS/MSAS
         6: RTK Float 3D network solution
         7: RTK Fixed 3D network solution
        8: RTK Float 2D network solution
         9: RTK Fixed 2D network solution
         10: OmniSTAR HP/XP solution
         11: OmniSTAR VBS solution
         12: Location RTK
         13: Beacon DGPS
  10     Number of satellites used in solution
  11     PDOP
  12     The checksum data, always begins with *
  ################
  22. RMC
  Position, velocity, and time

The RMC string is:

$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A
  GPRMC message fields
  Field     Meaning
  0     Message ID $GPRMC
  1     UTC of position fix
  2     Status A=active or V=void
  3     Latitude
  4     Longitude
  5     Speed over the ground in knots
  6     Track angle in degrees (True)
  7     Date
  8     Magnetic variation in degrees
  9     The checksum data, always begins with *
  ####################
  23. ROT
  Rate and direction of turn

An example of the ROT string is:

$GPROT,35.6,A*4E
  ROT message fields
  Field     Meaning
  0     Message ID $GPROT
  1     Rate of turn, degrees/minutes, “–” indicates bow turns to port
  2     A: Valid data
         V: Invalid data
  3     The checksum data, always begins with *
  ################
  24. VTG
  Track made good and speed over ground

An example of the VTG message string is:

$GPVTG,,T,,M,0.00,N,0.00,K*4E
  VTG message fields
  Field     Meaning
  0     Message ID $GPVTG
  1     Track made good (degrees true)
  2     T: track made good is relative to true north
  3     Track made good (degrees magnetic)
  4     M: track made good is relative to magnetic north
  5     Speed, in knots
  6     N: speed is measured in knots
  7     Speed over ground in kilometers/hour (kph)
  8     K: speed over ground is measured in kph
 9     The checksum data, always begins with *
  ################
  25. ZDA
  UTC day, month, and year, and local time zone offset

An example of the ZDA message string is:

$GPZDA,172809.456,12,07,1996,00,00*45
  ZDA message fields
  Field     Meaning
  0     Message ID $GPZDA
  1     UTC
  2     Day, ranging between 01 and 31
 3     Month, ranging between 01 and 12
  4     Year
  5     Local time zone offset from GMT, ranging from 00 through ±13 hours
  6     Local time zone offset from GMT, ranging from 00 through 59 minutes
  7     The checksum data, always begins with *

Fields 5 and 6 together yield the total offset. For example, if field 5 is -5 and field 6 is +15, local time is 5 hours and 15 minutes earlier than GMT.