About gpsd

gpsd is a service daemon that monitors one or more GPSes or AIS receivers attached to a host computer through serial or USB ports, making all data on the location/course/velocity of the sensors available to be queried on TCP port 2947 of the host computer.

With gpsd, multiple location-aware client applications can share access to supported sensors without contention or loss of data. Also, gpsd responds to queries with a format that is substantially easier to parse than the NMEA 0183 emitted by most GPSes. The gpsd distribution includes a linkable C service library, a C++ wrapper class, and a Python module that developers of gpsd-aware applications can use to encapsulate all communication with gpsd. Third-party client bindings for Java and Perl also exist.

Besides gpsd itself, the project provides auxiliary tools for diagnostic monitoring and profiling of receivers and feeding location-aware applications GPS/AIS logs for diagnostic purposes.

GPSD is everywhere in mobile embedded systems. It underlies the map service on Android phones. It's ubiquitous in drones, robot submarines, and driverless cars. It's increasingly common in recent generations of manned aircraft, marine navigation systems, and military vehicles.

Applications that presently use gpsd include pyGPS, gpsdrive, Kismet, GPSdrive, gpeGPS, position, roadmap, roadnav, navit, viking, tangogps, foxtrot, opencpn, obdgpslogger, geohist, LiveGPS, geoclue, qlandkartegt, gpredict, OpenCPN, gpsd-navigator, gpsd-ais-viewer, and firefox/mozilla. In addition, the Android smartphone operating system (from version 4.0 onwards and possibly earlier; we don't know for sure when the change happened) uses GPSD to monitor the phone's on-board GPS, so every location-aware Android app is indirectly a GPSD client.

GPSD is also extremely widely deployed in mobile embedded systems: it's a basic building block for navigation used by UAVs, robot submarines, and driverless cars as well as more conventional applications like marine navigation and military IFF systems.

Under Linux, gpsd normally runs with zero configuration. Binary packages for this program install hotplug scripts that do the right thing when a USB device goes active, launching gpsd if needed and telling gpsd which device to read data from. Then, gpsd deduces a baud rate and GPS/AIS type by looking at the data stream.

gpsd is high-quality, carefully-audited code; see our notes on reliability engineering. In January 2010, the GPSD project won the first Good Code Grant from the Alliance for Code Excellence.

Statistics about the code volume, commit history, and contributors associated with this project are available at Ohloh

Our development platforms are open-source Unixes — Linux, and the *BSD family. Presently Linux, OpenBSD and NetBSD are directly supported. The code is also exttremely widely deployed on Android phones. We'll support proprietary Unixes if it's not too much work (and it usually isn't). Apple's OS X is currently unsupported due to serial-layer issues. Older drivers are buggy and prevent gpsd from being able to read from USB-serial devices. No, we don't support Windows — get a better operating system.

If you represent a GPS manufacturer interested in qualifying your device for use with Linux and other open-source operating systems, we are your contact point. We'll need (1) on-line access to interface documentation, (2) a few (as in, no more than three) eval units, and (3) an engineering contact at your firm. For more, see our page welcoming vendor cooperation.

There are simple installation instructions for people running distributions with binary package systems. See the FAQ for information on how to report bugs.

If you appreciate GPSD, and especially if you make money from it, please @TIPLINK@.

News

This web page was last updated on @DATE@. You can browse the project's news file or to-do list here. Note: because of the way this website is maintained, these files may reflect the state of the repository tip (development version) rather than the latest released stable version.

Repository, Downloads and Packages

Project page
The main project page
Releases
Where to get release tarballs
Browse Code
Developer access to master git repository

If you are using a Debian-based distribution (including Ubuntu) you can probably install gpsd through your regular package manager or by typing "sudo apt-get install gpsd" at the command line.

Mailing Lists

There are four project mailing lists:

Documentation

The following manual pages describe the code. Note: because of the way this website is maintained, these files will describe the state and features of the repository tip (development version) rather than the latest stable version.

gpsd.8
The gpsd daemon.
gps.1
The gpsd test clients.
libgps.3
An interface library that manages communication with the daemon.
libgpsmm.3
C++ class wrapper for the libgps C binding.
gpsprof.1
The gpsprof program for plotting spatial scatter of fixes and fix latency.
gpsfake.1
The gpsfake test harness simulating a GPS.
gpsctl.1
The gpsctl tool for tweaking GPS settings.
gpscat.1
The gpscat tool dumps output from a serial device. Optionally, it can packetize the data.
gpsmon.1
The gpsmon real-time packet monitor and diagnostic tool. (This replaces the sirfmon tool in older versions.)
gpspipe.1
A simple client that captures GPS output and/or gpsd reports and sends it to standard output.
gpsdecode.1
The gpsdecode packet decoder.
gpsd.5
The request/response protocol of the gpsd daemon.
gpsinit.8
Initialize kernel modules for use with gpsd daemon.
gps2udp.1
Feed the take from gpsd to one or more aggregation sites via UDP.
ntpshmmon.1
Monitor the NTP shared-memory segments created by GPSD.

Also, see the FAQ.

We have a list of compatible GPSses with some technical information. We also have a list of NMEA sentences.

There is a Hacker's Guide to the project philosophy, design, and code internals. You should read this if you want to contribute code.

We maintain a GPS Hall of Shame that describes particularly egregious vendor blunders.

Real Time

Some of the developers hang out regularly on IRC at channel #gpsd at irc.freenode.net.

White Papers

GPSD
An in-depth essay on the architecture and practices of GPSD, published in The Architecture of Open Source, Volume 2.
GPSD Client HOWTO
A programmer's guide to interfacing with gpsd from client applications. Explains the theory, points at working example source code, warns you what the edge cases and gotchas are.
ESR's Guide to Hacking With GPS
If you are new to GPS technology and don't quite understand what gpsd is about, you might find this interesting.
Why GPSes suck, and what to do about it
The designer of gpsd 2.0 rants in an at least semi-humorous way about everything that's wrong with GPS standards and vendors.
GPSD-NG: A Case Study in Application Protocol Evolution
History and evolution of the GPSD-NG protocol, illuminating some larger trends in application protocol design.
Moving to GPSD-NG: a Guide for Client Developers
A practical explanation of GPSD-NG, and how to move to it as painlessly as possible.
Towards A Better GPS Protocol
An analysis of what's wrong with NMEA 0183, and a simple way to fix it.
Where's the Latency? Performance analysis of GPSes and GPSD
An analysis of latency in the GPS/GPSD system. Has implications for the design of gpsd and vendor claims about binary protocols.
Notes on Writing a GPSD Driver
A guide for the perplexed by the author of the Jupiter-T driver.
A Tour of the GPSD Internals
A walk through the code of GPSD. Written in 2007 and out of date in spots, but still quite useful for anyone interested in modifying the code.
GPSD and Code Excellence
An essay written for the The Alliance for Code Excellence on how GPSD drives out bad code.
Scenes from the Life of a System Architect
The GPSD lead describes some work in progress on the core code of GPSD. A slice of what doing software architecture is like in the real world, where history can weigh nearly as much as today's requirements list.
GPSD 3.0 finally ships. It's been a long epic.
What a long strange trip it's been. GPSD 3.0 ships, five years of effort pays off, and I think out loud about protocol transitions and ubiquity and what it's like to be an infrastructure gnome.
GPSD Time Service HOWTO
Step-by-step instructions on setting up a Stratum 1 time server using GPSD and either ntpd or chrony. Documents the black art of tuning offsets for remote time servers.
Introduction to Time Service
All about time service, reference clocks, strata, chimers, and other mysteries. Written as a companion to GPSD Time Service HOWTO for time-service novices.

Recipes and related resources

gpsd also works with some bluetooth GPS receivers. Warning: there are serious problems with the firmware in at least one family of Bluetooth implementations shipped by Holux that may result in gpsd bricking your GPS. See this bug warning for a description of the problem.

If you have an Android phone, it is possible to access its onboard GPS by pairing it as a Bluetooth device. Directions from Vargoville. There is also a GPS Tether app designed to work with GPSD, but it eems to be in early alpha.

The gGPSDproxy project is a small program which reads GPS data from a running gpsd process and forwards it to a remote server via an UDP connection. GPSDproxy is intended to be run on GPS enabled mobile devices.

You can read detailed instructions on Synchronizing ntpd to a Garmin GPS 18 LVC via gpsd. This may be a useful tutorial even if your actual device isn't a Garmin 18; many of the setup steps and caveats will be the same.

Diego Berge has written a prototype Qt-based client, basically xgps with a Qt look and feel.

Egil Möller has written agpsd, a gpsd replication and logging daemon with support for KML.

You can find Debian-unstable packages here.

gpsd is carried in the OpenBSD ports tree.

There's a Wiki page devoted to gpsd helper applications.

OpenStreetMap is a wiki aiming to build a freely available, world-wide streetmap.

Freedesktop.org is hosting a project called geoclue that aims to provide a location service layer for all D-Bus-using applications. It can use gpsd as a source for location info.

Notes on setting up reliable timekeeping using a Navisys GR-601W USB GPS can be found here.

Other GPSDs

There used to be three Linux-based forks of gpsd in the wild, but this GPSD project reabsorbed one and the other two are now defunct for unrelated reasons. You can read a brief history of the gpsd project if you are curious.

There is a project called gps3d that ships a gpsd with similar goals to ours, but which appears to be an independent development. There haven't been any releases since early 2002.

There is a GPSd project that is a GPS daemon written in Java and apparently intended to provide location information for browsers.

There is a gpsd-like hack hosted under Microsoft Windows. It provides gpsd service from data in netstumbler under win32. This way programs such as JiGLE can still get GPS data from netstumbler. This program is not genetically related to gpsd.

gpsfeed+ is a program that simulates the output of a GPS in motion, and can be used for testing GPS-aware applications.

We aren't Green Parrot Software Development, nor are we the Greenville Public School District nor the Greater Peoria Sanitary District, nor even the Greater Portland Soccer District, nor the Green Party of San Diego, nor do we have anything to do with the General Product Safety Directive, the Guiding Principles of Sustainable Design, nor the Glatt Plagiarism Self-Detection Program.

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