go-nmea

This is a NMEA library for the Go programming language (Golang).

Features

• Parse individual NMEA 0183 sentences
• Support for sentences with NMEA 4.10 "TAG Blocks"
• Register custom parser for unsupported sentence types
• User-friendly MIT license

Installing

To install go-nmea use go get:

go get github.com/adrianmo/go-nmea

This will then make the github.com/adrianmo/go-nmea package available to you.

Staying up to date

To update go-nmea to the latest version, use go get -u github.com/adrianmo/go-nmea.

Supported sentences

Sentence with link is supported by this library. NMEA0183 sentences list is based on IEC 61162-1:2016 (Edition 5.0 2016-08) table of contents.

Sentence	Description	References
AAM	Waypoint arrival alarm	gpsd
ABK	AIS addressed and binary broadcast acknowledgement
ABM	AIS addressed binary and safety related message
ACA	AIS channel assignment message
ACK	Acknowledge alarm
ACN	Alert command
ACS	AIS channel management information source
AIR	AIS interrogation request
AKD	Acknowledge detail alarm condition
ALA	Report detailed alarm condition
ALC	Cyclic alert list
ALF	Alert sentence
ALR	Set alarm state
APB	Heading/track controller (autopilot) sentence B	gpsd
ARC	Alert command refused
BBM	AIS broadcast binary message
BEC	Bearing and distance to waypoint, Dead reckoning	1
BOD	Bearing origin to destination	gpsd
BWC	Bearing and distance to waypoint, Great circle	gpsd
BWR	Bearing and distance to waypoint, Rhumb line	gpsd
BWW	Bearing waypoint to waypoint	gpsd
CUR	Water current layer, Multi-layer water current data
DBK	Depth Below Keel (obsolete, use DPT instead)	gpsd
DBS	Depth below transducer	gpsd
DBT	Depth below transducer	gpsd
DDC	Display dimming control
DOR	Door status detection
DPT	Depth	gpsd
DSC	Digital selective calling information
DSE	Expanded digital selective calling
DTM	Datum reference	gpsd
EPV	Command or report equipment property value
ETL	Engine telegraph operation status
EVE	General event message
FIR	Fire detection
FSI	Frequency set information
GBS	GNSS satellite fault detection
GEN	Generic binary information
GFA	GNSS fix accuracy and integrity
GGA	Global positioning system (GPS) fix data	1
GLL	Geographic position, Latitude/longitude	1
GNS	GNSS fix data	gpsd
GRS	GNSS range residuals
GSA	GNSS DOP and active satellites	1
GST	GNSS pseudorange noise statistics
GSV	GNSS satellites in view	1
HBT	Heartbeat supervision sentence
HCR	Heading correction report
HDG	Heading, deviation and variation	gpsd
HDM	Heading - Magnetic	gpsd
HDT	Heading true	gpsd
HMR	Heading monitor receive
HMS	Heading monitor set
HRM	heel angle, roll period and roll amplitude measurement device
HSC	Heading steering command	gpsd
HSS	Hull stress surveillance systems
HTC	Heading/track control command
HTD	Heading /track control data
LR1	AIS long-range reply sentence 1
LR2	AIS long-range reply sentence 2
LR3	AIS long-range reply sentence 3
LRF	AIS long-range function
LRI	AIS long-range interrogation
MDA	Meteorological Composite	gpsd
MTA	Air Temperature (obsolete, use XDR instead)
MOB	Man over board notification
MSK	MSK receiver interface
MSS	MSK receiver signal status
MTW	Water temperature	gpsd
MWD	Wind direction and speed	1
MWV	Wind speed and angle	gpsd
NAK	Negative acknowledgement
NRM	NAVTEX receiver mask
NRX	NAVTEX received message
NSR	Navigation status report
OSD	Own ship data	gpsd
POS	Device position and ship dimensions report or configuration command
PRC	Propulsion remote control status
RLM	Return link message
RMA	Recommended minimum specific LORAN-C data
RMB	Recommended minimum navigation information	gpsd
RMC	Recommended minimum specific GNSS data	1
ROR	Rudder order status
ROT	Rate of turn	gpsd
RRT	Report route transfer
RPM	Revolutions	gpsd
RSA	Rudder sensor angle	gpsd
RSD	Radar system data	gpsd
RTE	Routes	1
SFI	Scanning frequency information
SMI	SafetyNET Message, All Ships/NavArea
SM2	SafetyNET Message, Coastal Warning Area
SM3	SafetyNET Message, Circular Area address
SM4	SafetyNET Message, Rectangular Area Address
SMB	IMO SafetyNET Message Body
SPW	Security password sentence
SSD	AIS ship static data
STN	Multiple data ID
THS	True heading and status	1
TLB	Target label
TLL	Target latitude and longitude	gpsd
TRC	Thruster control data
TRL	AIS transmitter-non-functioning log
TRD	Thruster response data
TTD	Tracked target data
TTM	Tracked target message	gpsd
TUT	Transmission of multi-language text
TXT	Text transmission	NMEA
UID	User identification code transmission
VBW	Dual ground/water speed	gpsd
VDM	AIS VHF data-link message	gpsd
VDO	AIS VHF data-link own-vessel report	gpsd
VDR	Set and drift	gpsd
VER	Version
VHW	Water speed and heading	1
VLW	Dual ground/water distance	gpsd
VPW	Speed measured parallel to wind	gpsd
VSD	AIS voyage static data
VTG	Course over ground and ground speed	1
VWR	Relative Wind Speed and Angle	gpsd
VWT	True Wind Speed and Angle
WAT	Water level detection
WCV	Waypoint closure velocity
WNC	Distance waypoint to waypoint
WPL	Waypoint location	1
XDR	Transducer measurements	gpsd
XTE	Cross-track error, measured
XTR	Cross-track error, dead reckoning
ZDA	Time and date	1
ZDL	Time and distance to variable point
ZFO	UTC and time from origin waypoint
ZTG	UTC and time to destination waypoint

Proprietary sentence type	Description	References
PNG	Transfer NMEA2000 frame as NMEA0183 sentence (ShipModul MiniPlex-3)	1
PCDIN	Transfer NMEA2000 frame as NMEA0183 sentence (SeaSmart.Net Protocol)	1
PGRME	Estimated Position Error (Garmin proprietary sentence)	1
PHTRO	Vessel pitch and roll (Xsens IMU/VRU/AHRS)
PMTK001	Acknowledgement of previously sent command/packet	1
PRDID	Vessel pitch, roll and heading (Xsens IMU/VRU/AHRS)
PSKPDPT	Depth of Water for multiple transducer installation
PSONCMS	Quaternion, acceleration, rate of turn, magnetic field, sensor temperature (Xsens IMU/VRU/AHRS)

If you need to parse a message that contains an unsupported sentence type you can implement and register your own message parser and get yourself unblocked immediately. Check the example below to know how to implement and register a custom message parser. However, if you think your custom message parser could be beneficial to other users we encourage you to contribute back to the library by submitting a PR and get it included in the list of supported sentences.

Examples

Built-in message parsing

package main

import (
	"fmt"
	"log"
	"github.com/adrianmo/go-nmea"
)

func main() {
	sentence := "$GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70"
	s, err := nmea.Parse(sentence)
	if err != nil {
		log.Fatal(err)
	}
	if s.DataType() == nmea.TypeRMC {
		m := s.(nmea.RMC)
		fmt.Printf("Raw sentence: %v\n", m)
		fmt.Printf("Time: %s\n", m.Time)
		fmt.Printf("Validity: %s\n", m.Validity)
		fmt.Printf("Latitude GPS: %s\n", nmea.FormatGPS(m.Latitude))
		fmt.Printf("Latitude DMS: %s\n", nmea.FormatDMS(m.Latitude))
		fmt.Printf("Longitude GPS: %s\n", nmea.FormatGPS(m.Longitude))
		fmt.Printf("Longitude DMS: %s\n", nmea.FormatDMS(m.Longitude))
		fmt.Printf("Speed: %f\n", m.Speed)
		fmt.Printf("Course: %f\n", m.Course)
		fmt.Printf("Date: %s\n", m.Date)
		fmt.Printf("Variation: %f\n", m.Variation)
	}
}

Output:

$ go run main/main.go

Raw sentence: $GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70
Time: 22:05:16.0000
Validity: A
Latitude GPS: 5133.8200
Latitude DMS: 51° 33' 49.200000"
Longitude GPS: 042.2400
Longitude DMS: 0° 42' 14.400000"
Speed: 173.800000
Course: 231.800000
Date: 13/06/94
Variation: -4.200000

Customize sentence parser

Parser logic can be customized by creating nmea.SentenceParser instance and by providing callback implementations.

p := nmea.SentenceParser{
    CustomParsers: nil,
    ParsePrefix:   nil,
    CheckCRC:      nil,
    OnTagBlock:    nil,
}
s, err := p.Parse("$GPRMC,220516,A,5133.82,N,00042.24,W,173.8,231.8,130694,004.2,W*70")

TAG Blocks

NMEA 4.10 TAG Block values can be accessed via the message's TagBlock struct:

package main

import (
	"fmt"
	"log"
	"time"
	"github.com/adrianmo/go-nmea"
)

func main() {
	sentence := "\\s:Satelite_1,c:1553390539*62\\!AIVDM,1,1,,A,13M@ah0025QdPDTCOl`K6`nV00Sv,0*52"
	s, err := nmea.Parse(sentence)
	if err != nil {
		log.Fatal(err)
	}
	parsed := s.(nmea.VDMVDO)
	fmt.Printf("TAG Block timestamp: %v\n", time.Unix(parsed.TagBlock.Time, 0))
	fmt.Printf("TAG Block source:    %v\n", parsed.TagBlock.Source)
}

Output (locale/time zone dependent):

$  go run main/main.go

TAG Block timestamp: 2019-03-24 14:22:19 +1300 NZDT
TAG Block source:    Satelite_1

Custom message parsing

If you need to parse a message not supported by the library you can implement your own message parsing. The following example implements a parser for the hypothetical XYZ NMEA sentence type.

package main

import (
	"fmt"

	"github.com/adrianmo/go-nmea"
)

// A type to hold the parsed record
type XYZType struct {
	nmea.BaseSentence
	Time    nmea.Time
	Counter int64
	Label   string
	Value   float64
}

func main() {
	// Do this once it will error if you register the same type multiple times
	err := nmea.RegisterParser("XYZ", func(s nmea.BaseSentence) (nmea.Sentence, error) {
		// This example uses the package builtin parsing helpers
		// you can implement your own parsing logic also
		p := nmea.NewParser(s)
		return XYZType{
			BaseSentence: s,
			Time:         p.Time(0, "time"),
			Label:        p.String(1, "label"),
			Counter:      p.Int64(2, "counter"),
			Value:        p.Float64(3, "value"),
		}, p.Err()
	})

	if err != nil {
		panic(err)
	}

	sentence := "$00XYZ,220516,A,23,5133.82,W*42"
	s, err := nmea.Parse(sentence)
	if err != nil {
		panic(err)
	}

	switch m := s.(type) {
	case XYZType:
		fmt.Printf("Raw sentence: %v\n", m)
		fmt.Printf("Time: %s\n", m.Time)
		fmt.Printf("Label: %s\n", m.Label)
		fmt.Printf("Counter: %d\n", m.Counter)
		fmt.Printf("Value: %f\n", m.Value)
	default:
		panic("Could not parse XYZ sentence")
	}
}

Output:

$ go run main/main.go

Raw sentence: $AAXYZ,220516,A,23,5133.82,W*42
Time: 22:05:16.0000
Label: A
Counter: 23
Value: 5133.820000

Message parsing with optional values

Some messages have optional fields. By default, omitted numeric values are set to 0. In situations where you need finer control to distinguish between an undefined value and an actual 0, you can register types overriding existing sentences, using nmea.Int64 and nmea.Float64 instead of int64 and float64. The matching parsing methods are (*Parser).NullInt64 and (*Parser).NullFloat64. Both nmea.Int64 and nmea.Float64 contains a numeric field Value which is defined only if the field Valid is true.

See below example for a modified VTG sentence parser:

package main

import (
	"fmt"

	"github.com/adrianmo/go-nmea"
)

// VTG represents track & speed data.
// http://aprs.gids.nl/nmea/#vtg
type VTG struct {
	nmea.BaseSentence
	TrueTrack        nmea.Float64
	MagneticTrack    nmea.Float64
	GroundSpeedKnots nmea.Float64
	GroundSpeedKPH   nmea.Float64
}

func main() {
	nmea.MustRegisterParser("VTG", func(s nmea.BaseSentence) (nmea.Sentence, error) {
		p := nmea.NewParser(s)
		return VTG{
			BaseSentence:     s,
			TrueTrack:        p.NullFloat64(0, "true track"),
			MagneticTrack:    p.NullFloat64(2, "magnetic track"),
			GroundSpeedKnots: p.NullFloat64(4, "ground speed (knots)"),
			GroundSpeedKPH:   p.NullFloat64(6, "ground speed (km/h)"),
		}, p.Err()
	})

	sentence := "$GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05"
	s, err := nmea.Parse(sentence)
	if err != nil {
		panic(err)
	}

	m, ok := s.(VTG)
	if !ok {
		panic("Could not parse VTG sentence")
	}
	fmt.Printf("Raw sentence: %v\n", m)
	fmt.Printf("TrueTrack: %v\n", m.TrueTrack)
	fmt.Printf("MagneticTrack: %v\n", m.MagneticTrack)
	fmt.Printf("GroundSpeedKnots: %v\n", m.GroundSpeedKnots)
	fmt.Printf("GroundSpeedKPH: %v\n", m.GroundSpeedKPH)
}

Output:

$ go run main/main.go

Raw sentence: $GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05
TrueTrack: {140.88 true}
MagneticTrack: {0 false}
GroundSpeedKnots: {8.04 true}
GroundSpeedKPH: {14.89 true}

Contributing

Please feel free to submit issues or fork the repository and send pull requests to update the library and fix bugs, implement support for new sentence types, refactor code, etc.

License

Check LICENSE.