Here are the steps for installing gpsd and verifying its performance:

0. gpsd has a core set of prerequisites that are required for any
configuration of the package, and then additional features and tests
have additional prerequisites.

Necessary components for any build:

C compiler			-> gpsd and client library are written in C
Python				-> some code is generated from python scripts
Python GTK-2 and cairo bindings	-> the main test client, xgps, needs this

C99 conformance is required in the compiler. The C code depends on one
non-C99 feature: anonymous unions.  We could eliminate these, but the
cost would be source-level interface breakage if we have to move
structure members in and out of unions.

You will need Python 2.6 or 2.4+ & simplejson.  The Python code in
GPSD is 2.4-compatible except that you need either the json library
module from 2.6 or the functionally equivalent simplejson backport.
Note that while Python is required to *build* GPSD (the build uses
some code generators in Python), it is not required to run the service
daemon.  In particular, you can cross-compile onto an embeddeed system
without having to take Python with you.

Having the following optional components on your system will enable
various additional capabilities and extensions:

C++ compiler	       -> libgpsmm C++ wrapper for the library
pthreads library       -> support for PPS timekeeping on serial GPSes
DBUS                   -> gpsd will issue DBUS notifications 
ncurses                -> a test client and the GPS monitor depend on this
libusb-1.0.x or later  -> better USB device discovery
Qt + qmake             -> libQgpsmm depends on this

If you have libusb-1.0.0 or later, the GPSD build will autodetect
this and use it to discover Garmin USB GPSes, rather than groveling
through /proc/bus/usb/devices (which has been deprecated by the
Linux kernel team).

For working with DBUS, you'll need the DBUS development
headers and libraries installed.  Under Debian/Ubuntu these
are the packages ibdbus-1-dev and libdbus-glib-1-dev.

For building from the source tree, or if you change the man page
source, xslt and docbook xsl style files are used to generate nroff
-man source from docbook xml.  The following packages are used in this
process:

libxslt                -> xsltproc is used to build man pages from xml
docbook-xsl            -> style file for xml to man translation

The build degrades gracefully in the absence of any of these. You should
be able to tell from configure messages which extensions you will get.

Under Ubuntu and most other Debian-derived, an easy way to pick up
the prerequisites is: "apt-get build-dep gpsd"

If you are going to modify the build, you will need these:

autoconf 2.61 or later
automake 1.10 or later
libtool 2.26 or later
pkg-config

Once you have fetched the software prerequisites:

1. Start by making sure you can get data from your GPS, otherwise the later
steps will be very frustrating.  In this command

      stty -F /dev/ttyXXX ispeed 4800 && cat </dev/ttyXXX

replace ttyXXX with the filename of the port.  This will probably be
either /dev/ttyUSB0 or /dev/ttyS0.  When you run this command, you
should see text lines beginning with $ come to stdout (possibly after
a short initial burst of binary garbage).  If you don't see this, you
may have OS-level problems with your serial support, but more likely
have the wrong device.  Look again.

2. Ensure that device permissions will enable gpsd to read from and
write to GPS devices even after it drops root privileges.  If you are
running Fedora Core or Ubuntu you can skip this step, as the stock
configuration has the right properties.

gpsd requires two things: (1) that GPS devices have group read and
write enabled, and (2) all of them are have the same group ID as a 
prototypical device, typically /dev/ttyS0 under Linux or /dev/tty00
under *BSD. It does not actually matter what the owning group is, 
as gpsd will look this up on startup.  Alternatively, (3), you can
set a fallback group with the enable-gpsd-group in case the prototype
is not found: this should be the "dialout" group (or functional equivalent) 
that has write access to serial devices.

Before dropping privileges, gpsd will ensure that it has access to
devices given to it on the command line by forcing their group read
and write permissions on.

On a Linux with udev, check the files in /etc/udev/permissions.d to
ensure that /dev/tty* devices are all created with the same group 
and with 0660 permissions.

When gpsd drops privileges, its default is to set uid to 'nobody' and
group to the owning group of the prototype device (the configure
option --enable-gpsd-user=foo will cause gpsd to change to 'foo'
instead).

If your system has the Linux hotplug facility installed you can skip
the permission-setting part; the hotplug scripts will force the
permissions for you.  You still have to make sure all the tty devices
are in the same group.

3. Install prerequisites

Under Debian and Ubuntu ou can get all the build prerequisites
installed with "apt-get build-dep gpsd".

Note: if you are going to use the RTCM-104 support, you should compile
with gcc4; if you don't have it installed as your default 
compiler, do this by specifying CC=gcc4 before the configure
command.  The rtcm2.c file confuses the gcc-3.4.[23] optimizer
at -O2 level, making it generate incorrect code.

4. Build gpsd from source (skip this step if you have installed GPSD 
from a binary package).  As usual, the sequence is:

     ./configure && make

Mac OS X users may need to do "./configure --x-includes=/usr/X11R6/include"

5. Start gpsd.  You'll need to give it as an argument a path to 
a serial or USB port with a GPS attached to it.

6. Once gpsd is running, telnet to port 2947. You should see a
greeting line that's a JSON object describing GPSD's version.
Now plug in your GPS (or AIS receiver, or RTCM2 receiver).

7. Type '?WATCH={"enable":true,"json"};' to start raw and
watcher modes.  You should see lines beginning with '{' that are
JSON objects representing reports from your GPS; these are packet
translations in GPSD protocol.

8. Start the xgps client.  Calling it with no arguments should do the right 
thing.  You should see a GUI panel with position/velocity-time information,
and a satellite display.  The displays won't look very interesting until 
the GPS acquires satellite lock.

9. Now that you've verified that the code is working, "make install" 
will install it it in the system directories.  "make uninstall" will
undo this.

(You won't need to "make install" if you installed from a binary package.)

10. To enable hotplugging of USB GPSes under Linux, do a 'make udev-install' or
equivalent to put the appropriate udev rules and wrapper files in place.

11. Check out the list of supported hardware at 

   http://gpsd.berlios.de/hardware.html

If your GPS isn't on the list, please send us information to add a new
line to the table.  Directions are included on that page.

We can also use updates of the latest version number known to work with
hardware already supported.

12. Note for small embedded systems and those without threading.  It is
possible to build gpsd without thread support if you configure with
--disable-pps.  You'll lose support for updating the clock from PPS pulses.

13. Note for systems using DBUS: gpsd includes support for shipping fixes
as DBUS notifications, but it is not compiled in by default.  Configure 
with the option "--enable-dbus" to get it working.

14. The distribution includes a PHP script that you can use to
generate a PHP status page for your GPS.  You will need php and php-gd
installed.  To install it, copy the file 'gpsd.php' to your HTTP
document directory.  The first time it's invoked, it will generate a
file called 'gpsd_config.inc' containing configuration information;
edit to taste.  Note that for the Google Maps feature work you need
to set a valid Google API key in your config file.

15. libQgpsmm is a Qt version of the libgps/libgpsmm pair. Thanks to
the multi-platform approach of Qt, it allows the gpsd client library
to be available on all the Qt supported platforms.  Please see
http://qt.nokia.com/doc/4.6/supported-platforms.html for a status of
Qt supported platforms as of version 4.6.

You can build libQgpsmm if you have qmake and Qt (specifically the
(specifically QtCore and QtNetwork modules) version 4.5.3 or higher.
You will also need a C++ compiler supported by Qt (tested on GCC
4.4.0/mingw on Windows and GCC 4.1.2 on linux).

Building is done through a standard Qt .pro project file:
- Go to the libQgpsmm subdirectory of gpsd and execute "qmake" 
  to create the Makefiles
- execute "make" to build the library
- execute "make install" or equivalent to copy libgpsmm.h and the library 
  to the appropriate location for your platform.

Specifically for linux: You can specify the installation prefix by
running "qmake PREFIX=<installation_root>". Default value is
"/usr/local".

Please refer to Qt's documentation at
http://qt.nokia.com/doc/4.6/platform-specific.html for platform specific
building documentation

16. There are regression tests to verify proper operation of gpsd, and
it can be useful to run these to verify that all is well.  To run the
regression tests, first build gpsd from sources, and then run "make
check".  It is not necessary to install first, but you do need
to have "." in your $PATH to run regressions uninstalled.  Python is
required for regression tests.

17. If you installed from a .deb under Debian or a Debian-derived 
system, you may need to `dpkg-reconfigure -plow gpsd' to enable the
hotplug magic ("Start gpsd automatically").

18. Note for people using gpsd as time source for ntpd: In case you're
using dhcp3-client to configure your system, make sure you disable
/etc/dhcp3/dhclient-exit-hooks.d/ntp as dhclient would restart
ntpd with an automatically created ntp.conf otherwise - and gpsd
would not be ablt to talk with ntpd anymore.