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= gpsd README file
:date: 17 February 2021
:description: README for GPSD
:docinfodir: www
:keywords: GPSD, GPS
:robots: index,follow
:type: article
:toc: macro



The files at are NOT the gpsd
release files. DO NOT use them. The release files are at:


gpsd is a userland daemon acting as a translator between GPS, GNSS, and
AIS receivers and their clients. gpsd listens on port 2947 for clients
requesting position/time/velocity information. The receivers are
expected to generate position information in a well-known format -- as
NMEA-0183 sentences, SiRF binary, Rockwell binary, Garmin binary
format, or other vendor binary protocols. gpsd takes this
information from the GPS and translates it into something uniform and
easier to understand for clients. The distribution includes sample
clients, application interface libraries, and test/profiling tools.

The website for GPSD where you can find updates, news, and
project mailing lists is:

See that website for a list of GPS units known to be compatible.

See the file INSTALL.adoc for installation instructions and some tips on
how to troubleshoot your installation. The file build.adoc has
instructions for building from source. The packaging/ directory
contains resources and suggestions for packagers and distribution


This software (gpsd) is released under the terms and conditions of the BSD
License, a copy of which is included in the file COPYING.


Remco Treffkorn designed and originated the code.

Russ Nelson maintained gpsd for a couple of years.

Carsten Tschach's gpstrans-0.31b code was the original model for nmea_parse.c.

Bob Lorenzini <> provided testing and feedback.

Brook Milligan <brook@trillium.NMSU.Edu> combined gpsd and gpsclient
into one package and autoconfiscated it.

Derrick J. Brashear <> (KB3EGH) added code for the
EarthMate DeLorme. He also added "incredibly gross code to output
NMEA sentences" (his own words :-) He also did the first cut at
DGPS support (see,
for the Earthmate.

Curt Mills <> (WE7U) furthered the dgps support,
writing the portion for other GPS receivers.

None of these people have been active in 2.X and later versions; gpsd
has evolved out of recognition from the 1.X codebase.


Eric S. Raymond drastically rewrote this code in late 2004/early 2005
to clean it up and extend it. The 2.X architecture has become
significantly different and far more modularized. His new features

* Documentation (what a concept!)
* Cleaned up, simplified command-line options.
* Now understands the GLL (Geographic position - Latitude, Longitude)
sentence from NMEA 3.0.
* Now parses both the NMEA 3.01 and pre-3.01 variants of the VTG sentence
* New commands including 'y', 'w', and 'x', since obsolesced by a
JSON-based protocol.
* Massive refactoring -- one main loop now calls a self-contained
driver object for each type.
* The GPS-bashing code the daemon uses can now be directly linked as a
library, libgpsd(3).
* C and Python libraries are available to encapsulate the client side of
querying gpsd, see libgps(3).
* Cleaned-up error reporting, we don't use syslog when running in the foreground
but send all error and status messages to the tty instead.
* Added -n option to do batch monitoring of GPSes.
* xgpsspeed is working again; xgps has been seriously reworked and improved.
* RPMs which include installation of gpsd to start up at boot time
are available.
* New gpsprobe program probes the capabilities of GPSes and generates
error scattergrams from fixes. (Later this moved to gpsprof.)
* Autobauding, self-configuration, and hotplugging. gpsd can now get
its device from a hotplug script, and figures out itself which baud
rate to use and what the GPS's device type is.
* Support for SiRF binary mode.
* Support for RTCM104 and AIVDM.
* Support for multiple devices.
* Other test tools -- gpsfake, gpscat, gpsmon.

Chris Kuethe <> maintains the OpenBSD port, shipped
the 2.34 release, is our SiRF and low-level protocols expert, and does a
lot of general hacking and support. He has release authority.

Gary E. Miller <> wrote the driver for Garmin binary protocol
and most of the support for PPS handling on serial devices. He has release

Amaury Jacquot <> added DBUS support.

Ville Nuorvala <> wrote the NTRIP support.

We are delighted to acknowledge the assistance of Carl Carter, a field
application engineer at SiRF. He assisted us with the correction and
tuning of the SiRF binary-protocol driver, shedding a good deal of
light on murky aspects of the chip's behavior.

We are also delighted to acknowledge the assistance of Timo Ylhainen, VP of
Software Operations at Fastrax. He clarified some points about
the iTalk protocol, helping to further development of iTalk support.


The main feature of the 3.x versions is a stabilized and finalized
version of the JSON command/response protocol. This was designed and
mainly implemented by ESR. Gary E. Miller <> wrote the
subframe support, gpsplot, gpscsv, and gpssubframe.


*Project web site:* {gpsdweb}


This file is Copyright 2013 by the GPSD project +
SPDX-License-Identifier: BSD-2-clause