Editing NMEA 0183

{{short description|Communication standard for marine electronics}}
'''NMEA 0183''' is a combined electrical and data specification for communication between [[marine electronics]] such as [[echo sounder]], [[sonar]]s, [[anemometer]], [[gyrocompass]], [[Self-steering gear|autopilot]], [[GPS receiver]]s and many other types of instruments. It has been defined and is controlled by the [[National Marine Electronics Association]] (NMEA). It replaces the earlier '''NMEA 0180''' and '''NMEA 0182''' standards.<ref>{{cite web |url=http://www.kh-gps.de/nmea.faq |title=The NMEA FAQ |author=Peter Bennett |date=Sep 15, 1997 |access-date=2013-10-21 |url-status=dead |archive-url=https://web.archive.org/web/20140215150802/http://www.kh-gps.de/nmea.faq |archive-date=2014-02-15 }}</ref> In leisure marine applications, it is slowly being phased out in favor of the newer [[NMEA 2000]] standard,<ref name="NMEA2000wp">{{Cite web |url=https://www.https/ |title=NMEA 0183 vs NMEA 2000 |date=November 2018 |access-date=2020-10-20 |archive-date=2013-08-19 |archive-url=https://web.archive.org/web/20130819141428/http://https/ |url-status=dead }}</ref><ref>{{Cite web |url=https://www.nmea.org/Assets/20090423%20rtcm%20white%20paper%20nmea%202000.pdf |title=NMEA 2000 white paper |last=Spitzer |first=Steve. |date=May 2009 |access-date=2020-10-20 |archive-date=2021-03-02 |archive-url=https://web.archive.org/web/20210302230853/https://www.nmea.org/Assets/20090423%20rtcm%20white%20paper%20nmea%202000.pdf |url-status=dead }}</ref> though NMEA 0183 remains the norm in commercial shipping.

==Details==
The electrical standard that is used is [[EIA-422]], also known as RS-422, although most hardware with NMEA-0183 outputs are also able to drive a single [[EIA-232]] port. The standard calls for optically isolated inputs. There is no requirement for isolation for the outputs.

The NMEA 0183 standard uses a simple [[ASCII]], [[serial communications]] protocol that defines how data are 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.

While NMEA 0183 only defines an RS-422 transport, there also exists a de facto standard in which the sentences from NMEA 0183 are placed in [[User Datagram Protocol|UDP]] datagrams (one sentence per packet) and sent over an IP network.

The NMEA standard is proprietary and sells for at least US$2000 (except for members of the NMEA) as of September 2020.<ref name="NMEA0183">{{cite web |url=http://www.nmea.org/content/nmea_standards/nmea_0183_v_410.asp |title=Publications and Standards from the National Marine Electronics Association (NMEA) / NMEA 0183 |publisher=NMEA |date=November 2008 |access-date=2013-10-21 |archive-url=https://web.archive.org/web/20131021183159/http://www.nmea.org/content/nmea_standards/nmea_0183_v_410.asp |archive-date=2013-10-21 |url-status=dead }}</ref><ref>{{Cite web|title=National Marine Electronics Association - NMEA|url=https://www.nmea.org/content/STANDARDS/NMEA_0183_Standard|access-date=2020-09-24|website=www.nmea.org|archive-date=2022-03-31|archive-url=https://web.archive.org/web/20220331214516/https://www.nmea.org/content/STANDARDS/NMEA_0183_Standard|url-status=dead}}</ref> However, much of it has been reverse-engineered from public sources.<ref name="NMEA revealed">{{Cite web |url=https://gpsd.gitlab.io/gpsd/NMEA.html |title=NMEA Revealed |last=Raymond |first=Eric S. |date=March 2019}}</ref><ref>{{cite web|url=http://www.gpsinformation.org/dale/nmea.htm|title=NMEA data |author=Dale DePriest |archive-url=https://web.archive.org/web/20201020015948/http://www.gpsinformation.org/dale/nmea.htm |access-date=2020-10-20|archive-date=2020-10-20 }}</ref>

== UART settings ==
{| class="wikitable"
|-
| Typical [[Baud rate]] || 4800
|-
| 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 [[Automatic Identification System|AIS]] devices.

== Message structure ==
* All transmitted data are printable [[ASCII]] characters between 0x20 (space) to 0x7e (~) 
* Data characters are all the above characters except the reserved characters (See next line)
* Reserved characters are used by NMEA0183 for the following uses:
{| class="wikitable"
|-
! ASCII !! Hex !! Dec !! Use
|-
| <CR> || 0x0d || 13 || Carriage return
|-
| <LF> || 0x0a || 10 || Line feed, end delimiter
|-
| ! || 0x21 || 33 || Start of encapsulation sentence delimiter
|-
| $ || 0x24 || 36 || Start delimiter
|-
| * || 0x2a || 42 || Checksum delimiter
|-
| , || 0x2c || 44 || Field delimiter
|-
| \ || 0x5c || 92 || TAG block delimiter
|-
| ^ || 0x5e || 94 || Code delimiter for HEX representation of ISO/IEC 8859-1 (ASCII) characters
|-
| ~ || 0x7e || 126 || Reserved
|}
* Messages have a maximum length of 82 characters, including the $ or ! starting character and the ending <LF>
* The start character for each message can be either a $ (For conventional field delimited messages) or ! (for messages that have special encapsulation in them)
* 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 remains blank (it contains no character before the next delimiter – see [[#Sample file|Sample file]] section below).
* 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 [[checksum]] represented as a two-digit [[hexadecimal]] number. The checksum is the [[Bitwise XOR|bitwise exclusive OR]] of [[ASCII]] codes of all characters between the ''$'' and ''*'', not inclusive. According to the official specification, the checksum is optional for most data sentences, but is compulsory for RMA, RMB, and RMC (among others).
* [[Newline|{{code|<CR><LF>}}]] ends the message.

As an example, a waypoint arrival alarm has the form:
: ''$GPAAM,A,A,0.10,N,WPTNME*32''

Another example for AIS messages is:
:!AIVDM,1,1,,A,14eG;o@034o8sd<L9i:a;WF>062D,0*7D

== NMEA sentence format ==
The main talker ID includes:<ref>{{cite web|url=https://gpsd.gitlab.io/gpsd/NMEA.html#_talker_ids|title=NMEA Revealed - Talker IDs|author=[[Eric S. Raymond]]|date=2024-05-26|access-date=2024-05-31}}</ref><ref>{{cite web|url=https://www.nmea.org/Assets/NMEA%200183%20Talker%20Identifier%20Mnemonics.pdf|archive-url=https://web.archive.org/web/20220902160821/https://www.nmea.org/Assets/NMEA%200183%20Talker%20Identifier%20Mnemonics.pdf|title=NMEA 0183 - Standard For Interfacing Marine Electronic Devices - Talker Identifier Mnemonics|date=2020-01-31|archive-date=2022-09-02}}</ref>

* BD or GB - [[BeiDou|Beidou]]
* GA - [[Galileo (satellite navigation)|Galileo]]
* GP - [[Global Positioning System|GPS]]
* GL - [[GLONASS]].

NMEA message mainly include the following "sentences" in the NMEA message:<ref>{{cite web|url=https://fdocuments.in/document/introduction-to-gps-data-nmea-rtcm-donald-choi-alsg2.html|title=Introduction to GPS Data NMEA & RTCM|author=Donald Choi|page=15|access-date=2024-05-31}}{{dead link|date=March 2025}}</ref>
{| class="wikitable"
|+
!Sentence
!Description
|-
|$Talker ID+GGA
|Global Positioning System Fixed Data
|-
|$Talker ID+GLL
|Geographic Position—Latitude and Longitude 
|-
|$Talker ID+GSA
|GNSS DOP and active satellites
|-
|$Talker ID+GSV
|GNSS satellites in view
|-
|$Talker ID+RMC
|Recommended minimum specific GPS data
|-
|$Talker ID+VTG
|Course over ground and ground speed
|}
One example, the sentence for Global Positioning System Fixed Data for GPS should be "$GPGGA".

== Vendor extensions ==
Most GPS manufacturers include special messages in addition to the standard NMEA set in their products for maintenance and diagnostics purposes. Extended messages begin with "$P". These extended messages are not standardized.

== Software compatibility ==
NMEA 0183 is supported by various navigation and mapping software. Notable applications include:
* [https://play.google.com/store/apps/details?id=fi.hohtolabs.kuuratablet&hl=en%20US Infrakit SURVEY]
* [[DeLorme]] Street Atlas
* [[Environmental Systems Research Institute|ESRI]]
* [[Google Earth]]
* [[Google Maps]] Mobile Edition<ref>{{cite web|url=http://www.google.com/mobile/default/maps.html |title=Google Maps for Android |access-date=2013-10-21}}</ref>
* [[gpsd]] - [[Unix]] GPS Daemon
* [[JOSM]] - OpenStreetMap Map Editor
* [[MapKing]]
* [[Microsoft MapPoint]]
* [[Microsoft Streets & Trips]]
* [[NetStumbler]]
* [[OpenCPN]] - Open source navigation software
* [https://signalk.org Signal K] - Open source marine data aggregator
* [[OpenBSD]]'s [[hw.sensors]] framework with the <code>nmea(4)</code> [[pseudo-device]] driver<ref name=openbsd§nmea>{{cite web |author= Marc Balmer |date= 2006–2008 |url= http://bxr.su/o/sys/kern/tty_nmea.c |title= /sys/kern/tty_nmea.c |website= BSD Cross Reference |publisher= [[OpenBSD]]}}
*{{cite book |section=nmea — NMEA 0183 timedelta sensor |title=OpenBSD manual page server |url=http://mdoc.su/o/nmea.4}}</ref>
* [[OpenNTPD]] through sysctl {{Section link|hw.sensors#timedelta}} API
* [[Rand McNally]] StreetFinder
* ObserVIEW <ref>{{cite web|url=https://vibrationresearch.com/products/obserview/ |title=ObserVIEW - Free Vibration Analysis Software |access-date=2022-10-18}}</ref>
* [[QGIS]]<ref>{{cite web|url=https://github.com/qgis/QGIS-Documentation/blob/master/docs/user_manual/working_with_gps/live_GPS_tracking.rst |title=QGIS Documentation - Live GPS tracking |website=[[GitHub]] |access-date=2024-03-06}}</ref>

== Sample file ==
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A sample file produced by a Tripmate 850 GPS logger. This file was produced in [[Leixlip]], [[County Kildare]], [[Republic of Ireland|Ireland]]. The record lasts two seconds.

<pre>
$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
</pre>
Note some blank fields, for example:
* '''GSV''' records, which describe satellites 'visible', lack the SNR (signal–to–noise ratio) field for satellite 16 and all data for satellite 36.
* '''GSA''' record, which lists satellites used for determining a [[fix (position)]] and gives a [[Dilution of precision (GPS)|DOP]] of the fix, contains 12 fields for satellites' numbers, but only 8 satellites were taken into account—so 4 fields remain blank.

== Status ==
NMEA 0183 continued to be maintained separately: V4.10 was published in early May 2012, and an erratum noted on 12 May 2012.<ref>{{cite web |url=http://www.nmea.org/Assets/0183120512%20spo_errata.pdf |title=ERRATA # 0183 120512 |publisher=NMEA |date= |access-date=2013-10-21 |archive-date=2016-04-17 |archive-url=https://web.archive.org/web/20160417233915/http://www.nmea.org/Assets/0183120512%20spo_errata.pdf |url-status=dead }}</ref> 
On November 27, 2018, it was issued an update to version 4.11, which supports [[Global Navigation Satellite System]]s other than [[GPS]].<ref>{{cite web |url=https://www.nmea.org/Assets/nmea-updated-version-of-nmea-0183.pdf |title=NMEA PUBLISHES UPDATED VERSION OF NMEA 0183 FOR NEW GLOBAL SATELLITE SYSTEMS |date=November 2018 |access-date=2019-01-30 |archive-date=2019-01-31 |archive-url=https://web.archive.org/web/20190131040041/https://www.nmea.org/Assets/nmea-updated-version-of-nmea-0183.pdf |url-status=dead }}</ref>

== See also ==
* [[GPS Exchange Format]]
* [[TransducerML]]
* [[IEEE 1451]]
* [[IEC 61162]]
* [[NMEA 2000]]
* [[NMEA OneNet]]
* [[RTCM SC-104]]
* [[RINEX]]

== References ==

{{Reflist}}

== External links ==
* [http://www.nmea.org/ National Marine Electronics Association]
* [https://web.archive.org/web/20131021183159/http://www.nmea.org/content/nmea_standards/nmea_0183_v_410.asp NMEA's website about NMEA 0183]
* [http://aprs.gids.nl/nmea/ NMEA Specifications at APRS Info]

[[Category:Global Positioning System]]
[[Category:Network protocols]]
[[Category:Computer buses]]
[[Category:Marine electronics]]
[[Category:Satellite navigation]]