NMEA
Encyclopedia
NMEA 0183 is a combined electrical and data specification for communication between marine electronic devices such as echo sounder, sonars, anemometer
, gyrocompass
, autopilot
, GPS receivers and many other types of instruments. It has been defined by,
and is controlled by, the U.S.-based National Marine Electronics Association. It replaces the earlier NMEA 0180 and NMEA 0182 standards. In marine applications it is slowly being phased out in favor of the newer NMEA 2000
standard.
The electrical standard that is used is EIA-422
although most hardware with NMEA-0183 outputs are also able to drive a single EIA-232 port. Although the standard calls for isolated inputs and outputs there are various series of hardware that do not adhere to this requirement.
The NMEA 0183 standard uses a simple ASCII
, serial communications
protocol that defines how data is transmitted in a "sentence" from one "talker" to multiple "listeners" at a time. Through the use of intermediate expanders, a talker can have a unidirectional conversation with a nearly unlimited number of listeners, and using multiplexers, multiple sensors can talk to a single computer port.
At the application layer, the standard also defines the contents of each sentence (message) type so that all listeners can parse messages accurately.
There is a variation of the standard called NMEA-0183HS that specifies a baud rate of 38,400. This is in general use by AIS
devices.
As an example, a waypoint arrival alarm has the form:
where:
The new standard, NMEA 2000
, accommodates several talkers at a higher baud rate, without using a central hub.
The NMEA standard is proprietary and sells for at least US$ 325 as of June 2010. However, much of it has been reverse-engineered from public sources and is available in references like gpsd
and Dale DePriest's.
/******************************************************************************/
$GPGGA,092750.000,5321.6802,N,00630.3372,W,1,8,1.03,61.7,M,55.2,M,,*76
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,19,13,28,070,17,26,23,252,,04,14,186,14*79
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092750.000,A,5321.6802,N,00630.3372,W,0.02,31.66,280511,,,A*43
$GPGGA,092751.000,5321.6802,N,00630.3371,W,1,8,1.03,61.7,M,55.3,M,,*75
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,16,13,28,070,17,26,23,252,,04,14,186,15*77
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092751.000,A,5321.6802,N,00630.3371,W,0.06,31.66,280511,,,A*45
Anemometer
An anemometer is a device for measuring wind speed, and is a common weather station instrument. The term is derived from the Greek word anemos, meaning wind, and is used to describe any airspeed measurement instrument used in meteorology or aerodynamics...
, gyrocompass
Gyrocompass
A gyrocompass is a type of non-magnetic compass which bases on a fast-spinning disc and rotation of our planet to automatically find geographical direction...
, autopilot
Self-steering gear
Self-steering gear is equipment used on ships and boats to maintain a chosen course without constant human action. It is also known by several other terms, such as autopilot and autohelm...
, GPS receivers and many other types of instruments. It has been defined by,
and is controlled by, the U.S.-based National Marine Electronics Association. It replaces the earlier NMEA 0180 and NMEA 0182 standards. In marine applications it is slowly being phased out in favor of the newer NMEA 2000
NMEA 2000
NMEA 2000 is a combined electrical and data specification for a marine data network for communication between marine electronic devices such as depth finders, nautical chart plotters, navigation instruments, engines, tank level sensors, and GPS receivers...
standard.
The electrical standard that is used is EIA-422
EIA-422
RS-422 is a technical standard that specifies electrical characteristics of a digital signalling circuit. Differential-mode signals can be sent at rates as high as 10 million bits per second, or may be sent on cables as long as 1200 metres. Some systems directly interconnect using RS 422 signals,...
although most hardware with NMEA-0183 outputs are also able to drive a single EIA-232 port. Although the standard calls for isolated inputs and outputs there are various series of hardware that do not adhere to this requirement.
The NMEA 0183 standard uses a simple ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
, serial communications
Serial communications
In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels...
protocol that defines how data is transmitted in a "sentence" from one "talker" to multiple "listeners" at a time. Through the use of intermediate expanders, a talker can have a unidirectional conversation with a nearly unlimited number of listeners, and using multiplexers, multiple sensors can talk to a single computer port.
At the application layer, the standard also defines the contents of each sentence (message) type so that all listeners can parse messages accurately.
Serial configuration (data link layer)
| Typical Bit rate Bit rate In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time.... |
4,800 |
| Data bits | 8 |
| Parity | None |
| Stop bits | 1 |
| Handshake | None |
There is a variation of the standard called NMEA-0183HS that specifies a baud rate of 38,400. This is in general use by AIS
AIS
-As a word:* Ais people, a Native American tribe living on the Treasure coast of Florida, United States which had completely disappeared by the mid-18th Century.*Plural of:** ai ** AI -Medicine:...
devices.
Application layer protocol rules
- Each message's starting character is a dollar sign.
- The next five characters identify the talker (two characters) and the type of message (three characters).
- All data fields that follow are comma-delimited.
- Where data is unavailable, the corresponding field contains NUL bytes (e.g., in "123,,456", The double comma between 3 and 4 is telling the listener the second field's data is unavailable).
- The first character that immediately follows the last data field character is an asterisk, but it is only included if a checksum is supplied.
- The asterisk is immediately followed by a two-digit checksumChecksumA checksum or hash sum is a fixed-size datum computed from an arbitrary block of digital data for the purpose of detecting accidental errors that may have been introduced during its transmission or storage. The integrity of the data can be checked at any later time by recomputing the checksum and...
representing a hexadecimalHexadecimalIn mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
number. The checksum is the exclusive OR of all characters between the $ and *. According to the official specification, the checksum is optional for most data sentences, but is compulsory for RMA, RMB, and RMC (among others). - NewlineIn computing, a newline, also known as a line break or end-of-line marker, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the...
ends the message.
As an example, a waypoint arrival alarm has the form:
- $GPAAM,A,A,0.10,N,WPTNME*32
where:
| GP | Talker ID (GP for a GPS unit, GL for a GLONASS GLONASS GLONASS , acronym for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, is a radio-based satellite navigation system operated for the Russian government by the Russian Space Forces... ) |
| AAM | Arrival alarm |
| A | Arrival circle entered |
| A | Perpendicular passed |
| 0.10 | Circle radius |
| N | Nautical miles Nautical mile The nautical mile is a unit of length that is about one minute of arc of latitude along any meridian, but is approximately one minute of arc of longitude only at the equator... |
| WPTNME | Waypoint name |
| *32 | Checksum data |
The new standard, NMEA 2000
NMEA 2000
NMEA 2000 is a combined electrical and data specification for a marine data network for communication between marine electronic devices such as depth finders, nautical chart plotters, navigation instruments, engines, tank level sensors, and GPS receivers...
, accommodates several talkers at a higher baud rate, without using a central hub.
The NMEA standard is proprietary and sells for at least US$ 325 as of June 2010. However, much of it has been reverse-engineered from public sources and is available in references like gpsd
Gpsd
gpsd is a daemon that receives data from a GPS receiver, and provides the data back to multiple applications such as Kismet or GPS navigation software....
and Dale DePriest's.
Vendor extensions
Most GPS manufacturers include special messages in addition to the standard NMEA set in their products for maintenance and diagnostics purposes. These extended messages are not standardized at all and are normally different from vendor to vendor.Software compatibility
NMEA 0183 GPS compliant software:- Master Navigator Software (MNS) - Map and Navigation Software
- seaPro Navigation Software (www.euronav.co.uk)
- OrbitGPS
- ElectricCompass
- Telogis GeoBase
- NetStumblerNetStumblerNetStumbler is a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards. It runs on Microsoft Windows operating systems from Windows 2000 to Windows XP...
- Nimble Navigator - Marine Navigation and Charting Software
- Rand McNallyRand McNallyRand McNally is an American publisher of maps, atlases, textbooks, and globes for travel, reference, commercial, and educational uses. It also provides online consumer street maps and directions, as well as commercial transportation routing software and mileage data...
StreetFinder - Coastal Explorer by Rosepoint Navigation
- Magic e-Map
- GPS 2 IP - an iPhone NMEA server
- NemaTalker NMEA instrument simulation
- Microsoft Streets & Trips
- Microsoft MapPointMicrosoft MapPointMicrosoft MapPoint is both a technology and a specific software program created by Microsoft that allows users to view, edit and integrate maps. The software and technology are designed to facilitate the geographical visualization and analysis of either included data or custom data...
- Serotonin Mango M2M (suitable for NMEA compliant weather stations)
- MapKingMapKingMapKing is an automotive navigation systems and mapping solution brand focus in Asia Pacific. MapKing products include both stand-alone units, web map solution, software for personal digital assistants, and mobile telephones...
- gpsdGpsdgpsd is a daemon that receives data from a GPS receiver, and provides the data back to multiple applications such as Kismet or GPS navigation software....
- UnixUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
GPS Daemon - GPSy X for Mac OS X
- Turbo GPS PC/PPC/Android
- GRLevelX Weather Suite
- Google Maps Mobile Edition
- JOSM - OpenStreetMap Map Editor
- PolarCOM - a set of digital and analog NMEA instruments
- Avia Sail - PC instruments for both NMEA 0183 and NMEA 2000
- VisualGPS - A free NMEA Monitoring utility for NMEA 0183 GPS devices
- DeLormeDeLormeDeLorme is a major vendor of business-to-business and consumer mapping and GPS products and technologies. It is based in Yarmouth, Maine, United States....
Street Atlas - GPS TrackMaker - A Brazilian solution which supports many GPS brands
- Java Marine API - Open-source NMEA library for Java
Sample file
A sample file produced by a Tripmate 850 GPS logger. This file was produced in Leixlip co Kildare Rep of Ireland. The record lasts two seconds./******************************************************************************/
$GPGGA,092750.000,5321.6802,N,00630.3372,W,1,8,1.03,61.7,M,55.2,M,,*76
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,19,13,28,070,17,26,23,252,,04,14,186,14*79
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092750.000,A,5321.6802,N,00630.3372,W,0.02,31.66,280511,,,A*43
$GPGGA,092751.000,5321.6802,N,00630.3371,W,1,8,1.03,61.7,M,55.3,M,,*75
$GPGSA,A,3,10,07,05,02,29,04,08,13,,,,,1.72,1.03,1.38*0A
$GPGSV,3,1,11,10,63,137,17,07,61,098,15,05,59,290,20,08,54,157,30*70
$GPGSV,3,2,11,02,39,223,16,13,28,070,17,26,23,252,,04,14,186,15*77
$GPGSV,3,3,11,29,09,301,24,16,09,020,,36,,,*76
$GPRMC,092751.000,A,5321.6802,N,00630.3371,W,0.06,31.66,280511,,,A*45
See also
- NMEA 2000NMEA 2000NMEA 2000 is a combined electrical and data specification for a marine data network for communication between marine electronic devices such as depth finders, nautical chart plotters, navigation instruments, engines, tank level sensors, and GPS receivers...
- ASCIIASCIIThe American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
- Global Positioning SystemGlobal Positioning SystemThe Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
- Serial communicationsSerial communicationsIn telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels...
- Marine electronicsMarine electronicsMarine electronics refers to electronics devices designed and classed for use in the marine environment where even small drops of salt water will destroy electronics devices...
- Navigation system companies
- TransducerMLTransducermlTransducerML or TML is an Open Geospatial Consortium standard developed to describe any transducer in terms of a common model, including characterizing not only the data but XML formed metadata describing the system producing that data.-Process:TML captures when and where a sensor measurement or...
- IEEE 1451IEEE 1451IEEE 1451 is a set of smart transducer interface standards developed by the Institute of Electrical and Electronics Engineers Instrumentation and Measurement Society’s Sensor Technology Technical Committee that describe a set of open, common, network-independent communication interfaces for...
External links
- National Marine Electronics Association
- NMEA's website about NMEA 0183
- NMEA data information
- Sirf-Chipset NMEA data reference manual
- Free C library for parsing and generation of the NMEA protocol
- Free Java library for parsing of the NMEA protocol
- Open Source (New BSD License) C# library for parsing NMEA protocol
- NMEA Specifications at APRS Info
- MTK proprietary NMEA extensions