path: root/TODO

This is the gpsd to-do list.  If you're viewing it with Emacs, try
doing Ctl-C Ctl-t and browsing through the outline headers.  Ctl-C Ctl-a 
will unfold them again.

For contribution guidelines and internals documentation, please see
<http://gpsd.berlios.de/hacking.html>.

The list of bugs exposed by gpsd in other software has moved to
<http://gpsd.berlios.de/upstream-bugs.html>.

** Bugs in gpsd and its clients:

*** Tracker bugs

See the GPSD bug tracker at https://developer.berlios.de/bugs/?group_id=2116
but don't be surprised if it's empty or very sparse.  Our rate of new defects
per month is quite low.

*** Driver issues

**** gpsctl -b should work on UBX, but does not.

Presently this means there's no way to kick a UBX into returning
binary data.

** Ports

*** Windows port

Partially complete. David Ludlow <dave@adsllc.com> is working on it.

** To do:

*** Write advanced features for TNT Revolution device

The baud-rate switcher in the TNT driver needs to be tested.

gpsmon could support a number of TNT configuration commands, including
unit changes. See http://gpsd.googlecode.com/truenorth-reference.pdf
for possibilities.  

Jon Schlueter has one of these on a flock machine, so testing 
shouldn't be difficult.

*** Finish gpssim

It's blocked on skyview computation.

*** Complete and test the speed/parity/stopbit methods in the drivers

These are used for the '?DEVICE' command.  All work for 8N1.

**** superstar2: not implemented (driver is unfinished)
**** italk: not implemented (but could be)
**** tsip: speed tested, parity and stop-bit switching not tested
**** sirf: speed tested, parity and stop-bit switching not tested
**** evermore: speed tested, rejects parity/stopbit setting
**** ubx: fully implemented, parity and stop-bit switching not tested
**** zodiac: fully implemented, not tested
**** navcom.c: speed tested, rejects parity/stopbit setting

SiRF, UBX, TSIP, and even Zodiac can support non-8N1 modes; these need
to be tested.

*** Command to ship RTCM corrections to a specified device

At the moment, if a GPS accepts RTCM corrections and they are
available, gpsd ships them to the serial device from which the GPS is
reporting fix data.  Some GPSes have auxiliary ports for RTCM; 
there should be a (privileged) command to redirect RTCM connections.

*** Per-driver restore of changed config settings on exit.

This is a solved problem for generic NMEA, EverMore, TripMate,
EarthMate, TNTC, Zodiac, and RTCM104 drivers (if only because they
don't configure any device settings).

The SiRF driver now restores NMEA when necessary.  It also restores
some (but not all) of the things it tweaks in binary mode -- at the
moment, just the Navigation Parameters from message 0x13.  With more
work, we should be able to do a full revert.

The TSIP driver changes its per-cycle sentence inventory and thus 
needs some state-restore logic.  This can be done; the same packet 0x35
we use to configure it can be sent in a no-argument mode to query
the current sentence mix for later restore.

The FV18 changes its per-cycle sentence inventory to include GSAs. It
is possible to query that inventory, though we don't have code to do
it yet.

Garmin devices are a mess.  We reconfigure those heavily, and we
don't know if there's any way to capture their configuration state
before we do it.

The iTrax02 driver sets SYNCMODE to start navigation messages without
checking to see if it's already on, and stops navigation methods on
wrapup.  It also forces the set of sentences issued.  There doesn't
seem to be any way to query these settings.

*** Industry-standard format dumping of raw satellite data

It would be useful to be able to extract RINEX (or some other standard)
format data from any GPS device that can report pseudoranges etc.  This
belongs in the daemon because the device drivers are already doing the
packet-cracking needed to get the data off the chips.

Several commodity chipsets (ANTARIS, iTrax3, SiRF and Trimble) readily
output enough data to make this a chore, rather than a hard problem.
And pseudoranges, if available, are now part of the SKY report.

Probably the best way to do this would be to add support for unscaled
output of peudoranges in SKY and add clock and doppler carrier
phase. This message could then be interpreted by a client program.

There are numerous formats for this information, and it would be
easier to adapt to new formats if the formatting and use was handled
by something other than the gpsd daemon. Currently the RT-IGS format
is looking like the favorite for implementation; it's a fairly
lightweight protocol, flexible enough to handle all the quantities
required, and it is actually in use in production reference
networks. RT-IGS is also a packet-oriented format, rather than a
file-oriented format like RINEX.

*** RTCM3 support.

Previous plans for more RTCM2 support seem to have been overtaken by
events, e.g. the world moving to RTCM3. We have support for analyzing
RTCM3 messages, but it's entirely theoretical - written from the
standard.  We need to find a pair of files consisting of a
representative set of RTCM3 sentences and some sort of ASCII dump of
them so we can test whether our analyzer gets all the bitfield
boundaries right.

** Future features (?)

*** NOFLOAT build

We want to be able to build a minimalist version that doesn't require
floating-point arithmetic, for deployment on low-power ARM devices 
without FPU.

*** Support for more survey / professional / up-scale receivers.

Devices such as the Javad JNSCore, Hemisphere Crescent, Septentrio
AsteRx and PolaRx, NovAtel Superstar2 and OEMV, Thales (Magellan
Professional) AC12 and DG14 would all be welcome. Of course, these
are not $50 USB mice...

*** Audio cues in the client when the fix status changes

Calum writes:
>Is it possible to add functionality (with a switch to enable it to
>avoid annoying those that don't want it) so that beeps indicate NO
>FIX, FIX, and OFFLINE status changes?
>
>For example - I run cgps and my laptop battery doesn't always supply
>my PS2 port-powered GPS device with enough power, and it goes into
>OFFLINE mode. As I can't drive, and check my laptop all the time, if
>it emitted 5 1 second beeps when it went OFFLINE, it would be a handy alert.
>
>Similarly, a PCMCIA "eject" 2 beeps for NO FIX, and a PCMCIA "happy" 2
>beeps when it gets a fix again?
>
>Or something like that.

This is a good idea for supporting hands-free operation, e.g. while driving.

It would be an easy first project for somebody who wants to get into
the client code.

*** Enable gpsd to open chronyd socket as root in /var/run

At the moment gpsd drops privileges as soon as the command line
options are parsed.  A way needs to be found to open the chronyd
sockets in /var/run before dropping root.

*** Enhance libgps to decode SUBFRAME JSON

gpsd now passes along GPS subframe date in JSON.  The libgps needs to
be extended to decode this data.  A sample program to dump the SUBFRAME
data would also be useful.

*** Set the system time zone from latitude/longitude

If we're going to give gpsd the capability to set system time via
ntpd, why not let it set timezone as well?  A good thing for hackers
travelling with laptops!

The major issue here is that I have not yet found code, or a
database, that would allow mapping from lon/lat to timezone.
And the rules change from year to year.

Actually this should be built as a specialized client, as some
people won't want it.

From <http://www.linuxsa.org.au/tips/time.html>:

    The timezone under Linux is set by a symbolic link from
    /etc/localtime[1] to a file in the /usr/share/zoneinfo[2] directory
    that corresponds with what timezone you are in. For example, since I'm
    in South Australia, /etc/localtime is a symlink to
    /usr/share/zoneinfo/Australia/South. To set this link, type:

    ln -sf ../usr/share/zoneinfo/your/zone /etc/localtime

    Replace your/zone with something like Australia/NSW or
    Australia/Perth. Have a look in the directories under
    /usr/share/zoneinfo to see what timezones are available.

    [1] This assumes that /usr/share/zoneinfo is linked to /etc/localtime as it is under Red Hat Linux.

    [2] On older systems, you'll find that /usr/lib/zoneinfo is used
    instead of /usr/share/zoneinfo.

Changing the hardlink will, of course, update the system timezone for
all users.  If I were designing this feature, I'd ensure that the
system timezone can be overridden by a user-set TZ, but I don't know
if it actually works that way.

If I'm reading the tea leaves correctly, this functionality is actually
embedded in the GCC library version of tzset(), so the same method will
work on any system that uses that.

Problem: system daemons use the timezone set when they start up. You
can't get them to grok a new one short of rebooting.

Sources: 

Sources for Time Zone and Daylight Saving Time Data
http://www.twinsun.com/tz/tz-link.htm

Free time-zone maps of the U.S.
http://www.manifold.net/download/freemaps.html

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