NMEA Protocol
NMEA 0183 (or NMEA for short) is a combined electrical and data specification for communication between marine electronics and also, more generally, GPS receivers.
The NMEA 0183 protocol is a means by which marine instruments and also most GPS receivers can communicate with each other. It has been defined by, and is controlled by, the US based National Marine Electronics Association.
The 0183 standard, uses a simple serial protocol transmitting a “sentence” from one “talker” to one or more “listeners”.
See Wikipedia: NMEA
All $GPxxx sentence codes and short descriptions
- $GPAAM - Waypoint Arrival Alarm
- $GPALM - GPS Almanac Data
- $GPAPA - Autopilot format “A”
- $GPAPB - Autopilot format “B”
- $GPASD - Autopilot System Data
- $GPBEC - Bearing & Distance to Waypoint, Dead Reckoning
- $GPBOD - Bearing, Origin to Destination
- $GPBWC - Bearing & Distance to Waypoint, Great Circle
- $GPBWR - Bearing & Distance to Waypoint, Rhumb Line
- $GPBWW - Bearing, Waypoint to Waypoint
- $GPDBT - Depth Below Transducer
- $GPDCN - Decca Position
- $GPDPT - Depth
- $GPFSI - Frequency Set Information
- $GPGGA - Global Positioning System Fix Data
- $GPGLC - Geographic Position, Loran-C
- $GPGLL - Geographic Position, Latitude/Longitude
- $GPGRS - GPS Range Residuals
- $GPGSA - GPS DOP and Active Satellites
- $GPGST - GPS Pseudorange Noise Statistics
- $GPGSV - GPS Satellites in View
- $GPGXA - TRANSIT Position
- $GPHDG - Heading, Deviation & Variation
- $GPHDT - Heading, True
- $GPHSC - Heading Steering Command
- $GPLCD - Loran-C Signal Data
- $GPMSK - Control for a Beacon Receiver
- $GPMSS - Beacon Receiver Status
- $GPMTA - Air Temperature (to be phased out)
- $GPMTW - Water Temperature
- $GPMWD - Wind Direction
- $GPMWV - Wind Speed and Angle
- $GPOLN - Omega Lane Numbers
- $GPOSD - Own Ship Data
- $GPR00 - Waypoint active route (not standard)
- $GPRMA - Recommended Minimum Specific Loran-C Data
- $GPRMB - Recommended Minimum Navigation Information
- $GPRMC - Recommended Minimum Specific GPS/TRANSIT Data
- $GPROT - Rate of Turn
- $GPRPM - Revolutions
- $GPRSA - Rudder Sensor Angle
- $GPRSD - RADAR System Data
- $GPRTE - Routes
- $GPSFI - Scanning Frequency Information
- $GPSTN - Multiple Data ID
- $GPTRF - Transit Fix Data
- $GPTTM - Tracked Target Message
- $GPVBW - Dual Ground/Water Speed
- $GPVDR - Set and Drift
- $GPVHW - Water Speed and Heading
- $GPVLW - Distance Traveled through the Water
- $GPVPW - Speed, Measured Parallel to Wind
- $GPVTG - Track Made Good and Ground Speed
- $GPWCV - Waypoint Closure Velocity
- $GPWNC - Distance, Waypoint to Waypoint
- $GPWPL - Waypoint Location
- $GPXDR - Transducer Measurements
- $GPXTE - Cross-Track Error, Measured
- $GPXTR - Cross-Track Error, Dead Reckoning
- $GPZDA - UTC Date / Time and Local Time Zone Offset
- $GPZFO - UTC & Time from Origin Waypoint
- $GPZTG - UTC & Time to Destination Waypoint
26 interpreted sentences transmitted by GPS unit
$GPAAM
Waypoint Arrival Alarm
This sentence is generated by some units to indicate the Status of arrival (entering the arrival circle, or passing the perpendicular of the course line) at the destination waypoint.
$GPAAM,A,A,0.10,N,WPTNME*43 Where: AAM Arrival Alarm A Arrival circle entered A Perpendicular passed 0.10 Circle radius N Nautical miles WPTNME Waypoint name *43 Checksum data
$GPALM
GPS Almanac Data
A set of sentences transmitted by some Garmin units in response to a received $PGRMO,GPALM,1 sentence. It can also be received by some GPS units (eg. Garmin GPS 16 and GPS 17) to initialize the stored almanac information in the unit.
Example 1: $GPALM,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,*CC
1 = Total number of sentences in set 2 = Sentence sequence number in set 3 = Satellite number 4 = GPS week number 5 = Bits 17 to 24 of almanac page indicating SV health 6 = Eccentricity 7 = Reference time of almanac 8 = Inclination angle 9 = Right ascension rate 10 = Semi major axis route 11 = Argument of perigee (omega) 12 = Ascension node longitude 13 = Mean anomaly 14 = af0 clock parameter 15 = af1 clock parameter
Example 2: $GPALM,1,1,15,1159,00,441d,4e,16be,fd5e,a10c9f,4a2da4,686e81,58cbe1,0a4,001*5B
Field | Example | Comments |
---|---|---|
Sentence ID | $GPALM | |
Number of messages | 1 | Total number of messages in sequence |
Sequence number | 1 | This is first message in sequence |
Satellite PRN | 15 | Unique ID (PRN) of satellite message relates to |
GPS week number | 1159 | |
SV health | 00 | Bits 17-24 of almanac page |
Eccentricity | 441d | |
Reference time | 4e | Almanac reference time |
Inclination angle | 16be | |
Rate of right ascension | fd5e | |
Roor of semi-major axis | a10c9f | |
Argument of perigee | 4a2da4 | |
Longitude of ascension node | 686e81 | |
Mean anomoly | 58cbe1 | |
F0 clock parameter | 0a4 | |
F1 clock parameter | 001 | |
Checksum | *5B |
$GPAPB
Autopilot format “B”
This sentence is sent by some GPS receivers to allow them to be used to control an autopilot unit. This sentence is commonly used by autopilots and contains navigation receiver warning flag status, cross-track-error, waypoint arrival status, initial bearing from origin waypoint to the destination, continuous bearing from present position to destination and recommended heading-to-steer to destination waypoint for the active navigation leg of the journey.
Note: Some autopilots, Robertson in particular, misinterpret “bearing from origin to destination” as “bearing from present position to destination”. This is likely due to the difference between the APB sentence and the APA sentence. for the APA sentence this would be the correct thing to do for the data in the same field. APA only differs from APB in this one field and APA leaves off the last two fields where this distinction is clearly spelled out. This will result in poor performance if the boat is sufficiently off-course that the two bearings are different.
$GPAPB,A,A,0.10,R,N,V,V,011,M,DEST,011,M,011,M*82 where: APB Autopilot format B A Loran-C blink/SNR warning, general warning A Loran-C cycle warning 0.10 cross-track error distance R steer Right to correct (or L for Left) N cross-track error units - nautical miles (K for kilometers) V arrival alarm - circle V arrival alarm - perpendicular 011,M magnetic bearing, origin to destination DEST destination waypoint ID 011,M magnetic bearing, present position to destination 011,M magnetic heading to steer (bearings could True as 033,T)
$GPBOD
Bearing Origin to Destination
eg. BOD,045.,T,023.,M,DEST,START 045.,T bearing 045 degrees True from "START" to "DEST" 023.,M breaing 023 degrees Magnetic from "START" to "DEST" DEST destination waypoint ID START origin waypoint ID
Example 1: $GPBOD,099.3,T,105.6,M,POINTB,*01
Waypoint ID: “POINTB” Bearing 99.3 True, 105.6 Magnetic
This sentence is transmitted in the GOTO mode, without an active route on your GPS.
WARNING: this is the bearing from the moment you press enter in the GOTO
page to the destination waypoint and is NOT updated dynamically!
To update the information, (current bearing to waypoint), you will have to press enter in the GOTO page again.
Example 2: $GPBOD,097.0,T,103.2,M,POINTB,POINTA*52
This sentence is transmitted when a route is active. It contains the active leg information: origin waypoint “POINTA” and destination waypoint “POINTB”, bearing between the two points 97.0 True, 103.2 Magnetic. It does NOT display the bearing from current location to destination waypoint!
WARNING Again this information does not change until you are on the next leg of the route. (The bearing from POINTA to POINTB does not change during the time you are on this leg.)
$GPBWC
Bearing and distance to waypoint, great circle
eg1. $GPBWC,081837,,,,,,T,,M,,N,*13 BWC,225444,4917.24,N,12309.57,W,051.9,T,031.6,M,001.3,N,004*29 225444 UTC time of fix 22:54:44 4917.24,N Latitude of waypoint 12309.57,W Longitude of waypoint 051.9,T Bearing to waypoint, degrees true 031.6,M Bearing to waypoint, degrees magnetic 001.3,N Distance to waypoint, Nautical miles 004 Waypoint ID eg2. $GPBWC,220516,5130.02,N,00046.34,W,213.8,T,218.0,M,0004.6,N,EGLM*11 1 2 3 4 5 6 7 8 9 10 11 12 13 1 220516 timestamp 2 5130.02 Latitude of next waypoint 3 N North/South 4 00046.34 Longitude of next waypoint 5 W East/West 6 213.0 True track to waypoint 7 T True Track 8 218.0 Magnetic track to waypoint 9 M Magnetic 10 0004.6 range to waypoint 11 N unit of range to waypoint, N = Nautical miles 12 EGLM Waypoint name 13 *11 checksum
$GPGGA
Global Positioning System Fix Data
eg1. $GPGGA,170834,4124.8963,N,08151.6838,W,1,05,1.5,280.2,M,-34.0,M,,,*75
Name | Example Data | Description |
---|---|---|
Sentence Identifier | $GPGGA | Global Positioning System Fix Data |
Time | 170834 | 17:08:34 UTC |
Latitude | 4124.8963, N | 41d 24.8963' N or 41d 24' 54“ N |
Longitude | 08151.6838, W | 81d 51.6838' W or 81d 51' 41” W |
Fix Quality: * 0 = Invalid * 1 = GPS fix * 2 = DGPS fix | 1 | Data is from a GPS fix |
Number of Satellites | 05 | 5 Satellites are in view |
Horizontal Dilution of Precision (HDOP) | 1.5 | Relative accuracy of horizontal position |
Altitude | 280.2, M | 280.2 meters above mean sea level |
Height of geoid above WGS84 ellipsoid | -34.0, M | -34.0 meters |
Time since last DGPS update | blank | No last update |
DGPS reference station id | blank | No station id |
Checksum | *75 | Used by program to check for transmission errors |
Global Positioning System Fix Data.
Time, position and fix related data for a GPS receiver.
eg2. $GPGGA,hhmmss.ss,ddmm.mmm,a,dddmm.mmm,b,q,xx,p.p,a.b,M,c.d,M,x.x,nnnn
hhmmss.ss = UTC of position
ddmm.mmm = latitude of position
a = N or S, latitutde hemisphere
dddmm.mmm = longitude of position
b = E or W, longitude hemisphere
q = GPS Quality indicator (0=No fix, 1=Non-differential GPS fix, 2=Differential GPS fix, 6=Estimated fix)
xx = number of satellites in use
p.p = horizontal dilution of precision
a.b = Antenna altitude above mean-sea-level
M = units of antenna altitude, meters
c.d = Geoidal height
M = units of geoidal height, meters
x.x = Age of Differential GPS data (seconds since last valid RTCM transmission)
nnnn = Differential reference station ID, 0000 to 1023
$GPGLL
Geographic Position, Latitude / Longitude and time.
eg1. $GPGLL,3751.65,S,14507.36,E*77 eg2. $GPGLL,4916.45,N,12311.12,W,225444,A 4916.46,N Latitude 49 deg. 16.45 min. North 12311.12,W Longitude 123 deg. 11.12 min. West 225444 Fix taken at 22:54:44 UTC A Data valid eg3. $GPGLL,5133.81,N,00042.25,W*75 1 2 3 4 5 1 5133.81 Current latitude 2 N North/South 3 00042.25 Current longitude 4 W East/West 5 *75 checksum
$–GLL,lll.ll,a,yyyyy.yy,a,hhmmss.ss,A llll.ll = Latitude of position
a = N or S
yyyyy.yy = Longitude of position
a = E or W
hhmmss.ss = UTC of position
A = status: A = valid data
$GPGRS
GPS Range Residuals
Example: $GPGRS,024603.00,1,-1.8,-2.7,0.3,,,,,,,,,*6C
Field | Example | Comments |
---|---|---|
Sentence ID | $GPGRS | |
UTC Time | 024603.00 | UTC time of associated GGA fix |
Mode | 1 | 0 = Residuals used in GGA, 1 = residuals calculated after GGA |
Sat 1 residual | -1.8 | Residual (meters) of satellite 1 in solution |
Sat 2 residual | -2.7 | The order matches the PRN numbers in the GSA sentence |
Sat 3 residual | 0.3 | |
Sat 4 residual | Unused entries are blank | |
Sat 5 residual | ||
Sat 6 residual | ||
Sat 7 residual | ||
Sat 8 residual | ||
Sat 9 residual | ||
Sat 10 residual | ||
Sat 11 residual | ||
Sat 12 residual | ||
Checksum | *6C |
$GPGSA
GPS DOP and active satellites
eg1. $GPGSA,A,3,,,,,,16,18,,22,24,,,3.6,2.1,2.2*3C eg2. $GPGSA,A,3,19,28,14,18,27,22,31,39,,,,,1.7,1.0,1.3*34 1 = Mode: M=Manual, forced to operate in 2D or 3D A=Automatic, 3D/2D 2 = Mode: 1=Fix not available 2=2D 3=3D 3-14 = PRN's of Satellite Vechicles (SV's) used in position fix (null for unused fields) 15 = Position Dilution of Precision (PDOP) 16 = Horizontal Dilution of Precision (HDOP) 17 = Vertical Dilution of Precision (VDOP)
$GPGST
GPS Pseudorange Noise Statistics
Example: $GPGST,024603.00,3.2,6.6,4.7,47.3,5.8,5.6,22.0*58
Field | Example | Comments |
---|---|---|
Sentence ID | $GPGST | |
UTC Time | 024603.00 | UTC time of associated GGA fix |
RMS deviation | 3.2 | Total RMS standard deviation of ranges inputs to the navigation solution |
Semi-major deviation | 6.6 | Standard deviation (meters) of semi-major axis of error ellipse |
Semi-minor deviation | 4.7 | Standard deviation (meters) of semi-minor axis of error ellipse |
Semi-major orientation | 47.3 | Orientation of semi-major axis of error ellipse (true north degrees) |
Latitude error deviation | 5.8 | Standard deviation (meters) of latitude error |
Longitude error deviation | 5.6 | Standard deviation (meters) of longitude error |
Altitude error deviation | 22.0 | Standard deviation (meters) of latitude error |
Checksum | *58 |
$GPGSV
GPS Satellites in view
eg. $GPGSV,3,1,11,03,03,111,00,04,15,270,00,06,01,010,00,13,06,292,00*74 $GPGSV,3,2,11,14,25,170,00,16,57,208,39,18,67,296,40,19,40,246,00*74 $GPGSV,3,3,11,22,42,067,42,24,14,311,43,27,05,244,00,,,,*4D $GPGSV,1,1,13,02,02,213,,03,-3,000,,11,00,121,,14,13,172,05*62 1 = Total number of messages of this type in this cycle 2 = Message number 3 = Total number of SVs in view 4 = SV PRN number 5 = Elevation in degrees, 90 maximum 6 = Azimuth, degrees from true north, 000 to 359 7 = SNR, 00-99 dB (null when not tracking) 8-11 = Information about second SV, same as field 4-7 12-15= Information about third SV, same as field 4-7 16-19= Information about fourth SV, same as field 4-7
$GPHDT
Heading, True.
Actual vessel heading in degrees Ture produced by any device or system producing true heading.
$–HDT,x.x,T
x.x = Heading, degrees True
$GPMSK
Control for a Beacon Receiver
$GPMSK,318.0,A,100,M,2*45 where: 318.0 Frequency to use A Frequency mode, A=auto, M=manual 100 Beacon bit rate M Bitrate, A=auto, M=manual 2 frequency for MSS message status (null for no status) *45 checksum
$GPMSS
Beacon Receiver Status
Example 1: $GPMSS,55,27,318.0,100,*66
where: 55 signal strength in dB 27 signal to noise ratio in dB 318.0 Beacon Frequency in KHz 100 Beacon bitrate in bps *66 checksum
Example 2: $GPMSS,0.0,0.0,0.0,25,2*6D
Field | Example | Comments |
---|---|---|
Sentence ID | $GPMSS | |
Signal strength | 0.0 | Signal strength (dB 1uV) |
SNR | 0.0 | Signal to noise ratio (dB) |
Frequency | 0.0 | Beacon frequency (kHz) |
Data rate | 25 | Beacon data rate (BPS) |
Unknown field | 2 | Unknown field sent by GPS receiver used for test |
Checksum | *6D |
$GPR00
List of waypoint IDs in currently active route
eg1. $GPR00,EGLL,EGLM,EGTB,EGUB,EGTK,MBOT,EGTB,,,,,,,*58 eg2. $GPR00,MINST,CHATN,CHAT1,CHATW,CHATM,CHATE,003,004,005,006,007,,,*05 List of waypoints. This alternates with $GPWPL cycle which itself cycles waypoints.
$GPRMA
Recommended minimum specific Loran-C data
eg. $GPRMA,A,lll,N,lll,W,x,y,ss.s,ccc,vv.v,W*hh A = Data status lll = Latitude N = N/S lll = longitude S = W/E x = not used y = not used ss.s = Speed over ground in knots ccc = Course over ground vv.v = Variation W = Direction of variation E/W hh = Checksum
$GPRMB
Recommended minimum navigation information (sent by nav. receiver when a destination waypoint is active)
eg1. $GPRMB,A,0.66,L,003,004,4917.24,N,12309.57,W,001.3,052.5,000.5,V*0B A Data status A = OK, V = warning 0.66,L Cross-track error (nautical miles, 9.9 max.), steer Left to correct (or R = right) 003 Origin waypoint ID 004 Destination waypoint ID 4917.24,N Destination waypoint latitude 49 deg. 17.24 min. N 12309.57,W Destination waypoint longitude 123 deg. 09.57 min. W 001.3 Range to destination, nautical miles 052.5 True bearing to destination 000.5 Velocity towards destination, knots V Arrival alarm A = arrived, V = not arrived *0B mandatory checksum eg2. $GPRMB,A,4.08,L,EGLL,EGLM,5130.02,N,00046.34,W,004.6,213.9,122.9,A*3D 1 2 3 4 5 6 7 8 9 10 11 12 13 1 A validity 2 4.08 off track 3 L Steer Left (L/R) 4 EGLL last waypoint 5 EGLM next waypoint 6 5130.02 Latitude of Next waypoint 7 N North/South 8 00046.34 Longitude of next waypoint 9 W East/West 10 004.6 Range 11 213.9 bearing to waypt. 12 122.9 closing velocity 13 A validity 14 *3D checksum eg3. $GPRMB,A,x.x,a,c--c,d--d,llll.ll,e,yyyyy.yy,f,g.g,h.h,i.i,j*kk 1 = Data Status (V=navigation receiver warning) 2 = Crosstrack error in nautical miles 3 = Direction to steer (L or R) to correct error 4 = Origin waypoint ID# 5 = Destination waypoint ID# 6 = Destination waypoint latitude 7 = N or S 8 = Destination waypoint longitude 9 = E or W 10 = Range to destination in nautical miles 11 = Bearing to destination, degrees True 12 = Destination closing velocity in knots 13 = Arrival status; (A=entered or perpendicular passed) 14 = Checksum
$GPRMC
Recommended minimum specific GPS/Transit data
eg1. $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62 eg2. $GPRMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E*68 225446 Time of fix 22:54:46 UTC A Navigation receiver warning A = Valid position, V = Warning 4916.45,N Latitude 49 deg. 16.45 min. North 12311.12,W Longitude 123 deg. 11.12 min. West 000.5 Speed over ground, Knots 054.7 Course Made Good, degrees true 191194 UTC Date of fix, 19 November 1994 020.3,E Magnetic variation, 20.3 deg. East *68 mandatory checksum eg3. $GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70 1 2 3 4 5 6 7 8 9 10 11 12 1 220516 Time Stamp 2 A validity - A-ok, V-invalid 3 5133.82 current Latitude 4 N North/South 5 00042.24 current Longitude 6 W East/West 7 173.8 Speed in knots 8 231.8 True course 9 130694 Date Stamp 10 004.2 Variation 11 W East/West 12 *70 checksum eg4. for NMEA 0183 version 3.00 active the Mode indicator field is added $GPRMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,ddmmyy,x.x,a,m*hh Field # 1 = UTC time of fix 2 = Data status (A=Valid position, V=navigation receiver warning) 3 = Latitude of fix 4 = N or S of longitude 5 = Longitude of fix 6 = E or W of longitude 7 = Speed over ground in knots 8 = Track made good in degrees True 9 = UTC date of fix 10 = Magnetic variation degrees (Easterly var. subtracts from true course) 11 = E or W of magnetic variation 12 = Mode indicator, (A=Autonomous, D=Differential, E=Estimated, N=Data not valid) 13 = Checksum
$GPRTE
Routes
eg. $GPRTE,2,1,c,0,PBRCPK,PBRTO,PTELGR,PPLAND,PYAMBU,PPFAIR,PWARRN,PMORTL,PLISMR*73 $GPRTE,2,2,c,0,PCRESY,GRYRIE,GCORIO,GWERR,GWESTG,7FED*34 1 2 3 4 5 ..
- Number of sentences in sequence
- Sentence number
- 'c' = Current active route, 'w' = waypoint list starts with destination waypoint
- Name or number of the active route
- onwards, Names of waypoints in Route
$GPTRF
Transit Fix Data
Time, date, position, and information related to a TRANSIT Fix.
$–TRF,hhmmss.ss,xxxxxx,llll.ll,a,yyyyy.yy,a,x.x,x.x,x.x,x.x,xxx
hhmmss.ss = UTC of position fix
xxxxxx = Date: dd/mm/yy
llll.ll,a = Latitude of position fix, N/S
yyyyy.yy,a = Longitude of position fix, E/W
x.x = Elevation angle
x.x = Number of iterations
x.x = Number of Doppler intervals
x.x = Update distance, nautical miles
x.x = Satellite ID
$GPSTN
Multiple Data ID.
This sentence is transmitted before each individual sentence where there is a need for the Listener to determine the exact source of data in the system. Examples might include dual-frequency depthsounding equipment or equipment that integrates data from a number of sources and produces a single output.
$–STN,xx
xx = Talker ID number, 00 to 99
$GPVBW
Dual Ground / Water Speed
Water referenced and ground referenced speed data.
$–VBW,x.x,x.x,A,x.x,x.x,A
x.x = Longitudinal water speed, knots
x.x = Transverse water speed, knots
A = Status: Water speed, A = Data valid
x.x = Longitudinal ground speed, knots
x.x = Transverse ground speed, knots
A = Status: Ground speed, A = Data valid
$GPVTG
Track Made Good and Ground Speed.
eg1. $GPVTG,360.0,T,348.7,M,000.0,N,000.0,K*43 eg2. $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K*41 054.7,T True course made good over ground, degrees 034.4,M Magnetic course made good over ground, degrees 005.5,N Ground speed, N=Knots 010.2,K Ground speed, K=Kilometers per hour eg3. for NMEA 0183 version 3.00 active the Mode indicator field is added at the end $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K,A*53 A Mode indicator (A=Autonomous, D=Differential, E=Estimated, N=Data not valid)
$GPWPL
Waypoint location
eg1. $GPWPL,4917.16,N,12310.64,W,003*65 4917.16,N Latitude of waypoint 12310.64,W Longitude of waypoint 003 Waypoint ID When a route is active, this sentence is sent once for each waypoint in the route, in sequence. When all waypoints have been reported, GPR00 is sent in the next data set. In any group of sentences, only one WPL sentence, or an R00 sentence, will be sent. eg2. $GPWPL,5128.62,N,00027.58,W,EGLL*59 1 2 3 4 5 6 1 5128.62 Latitude of nth waypoint on list 2 N North/South 3 00027.58 Longitude of nth waypoint 4 W East/West 5 EGLL Ident of nth waypoint 6 *59 checksum
$GPXTE
Cross Track Error, Measured
eg1. $GPXTE,A,A,0.67,L,N A General warning flag V = warning (Loran-C Blink or SNR warning) A Not used for GPS (Loran-C cycle lock flag) 0.67 cross track error distance L Steer left to correct error (or R for right) N Distance units - Nautical miles eg2. $GPXTE,A,A,4.07,L,N*6D 1 2 3 4 5 6 1 A validity 2 A cycle lock 3 4.07 distance off track 4 L steer left (L/R) 5 N distance units 6 *6D checksum
$GPZDA
UTC Date / Time and Local Time Zone Offset
Example 1: $GPZDA,hhmmss.ss,xx,xx,xxxx,xx,xx
hhmmss.ss = UTC xx = Day, 01 to 31 xx = Month, 01 to 12 xxxx = Year xx = Local zone description, 00 to +/- 13 hours xx = Local zone minutes description (same sign as hours)
Example 2: $GPZDA,024611.08,25,03,2002,00,00*6A
Field | Example | Comments |
---|---|---|
Sentence ID | $GPZDA | |
UTC Time | 024611.08 | UTC time |
UTC Day | 25 | UTC day (01 to 31) |
UTC Month | 03 | UTC month (01 to 12) |
UTC Year | 2002 | UTC year (4 digit format) |
Local zone hours | 00 | Offset to local time zone in hours (+/- 00 to +/- 59) |
Local zone minutes | 00 | Offset to local time zone in minutes (00 to 59) |
Checksum | *6A |