GPS

[Daniel Willmann]

Hi,

On Thu, 3 Jul 2008 11:49:51 +0200
Tim Niemeyer <tim.niemeyer at mastersword.de> wrote:

> i have thought about the GPS Interface and i noted some things to my
> paper. I hope somebody can read my english.

> Any comments are gladly welcome..

nice, thanks for the thoughts.

> ---------------------------------------
> 
> What we have:
> -GTA01: GLLIN sends nmea to /tmp/nmeaNP

or GLLIN sends NMEA to UDP port

> -GTA02: GPS-Chips send nmea to serial Port

or U-Blox Antaris4 uses UBX protocol to communicate. This enables us to
do some cool stuff like {A,D}GPS, changing the dynamics model, etc..

> -GTAxx: ?

Hopefully U-Blox5, probably still over serial

> How we get this:
> -GTA01: checking if gllin is there, starting gllin
> -GTA02: echo 1 > /sys/...
> -GTAxx: ?

We have ousaged where programs will be able to indicate what resources
they need. ousaged will then tell ogpsd (just committed some work on
that) to turn GPS on or off.

> What we want to put into dbus:
> -Only the request for one of the following

> What we want to get out of dbus:
> -Time

We actually get Time from org.freedesktop.Gypsy.Time

> -Position*
> -Course*
> -Accurary*
> -Satellite*
> -Speed

Speed is included in org.freedesktop.Gypsy.Course

> What we need to handle in between:
> -Suspend/Resume

Right, the problem on GTA02 is if we cut power to GPS in suspend we'll
loose ephemeris and almanac. We need to see whether loading that via
UBX is sufficient enough to get away with that.

> What would be nice, but can be done in some years:
> -AGPS
> -DGPS

Well, due to the GPS power issues with GTA02 some form of AGPS would
be really good to have.

> ----------------------------------------
> 
> Ok, Gypsy can do the things with *. But all the other it could not.

See above.

> Gypsy, as it is, is not what we want because the applications have to
> configure from where to get the GPS-Data.

Yeah. My plan is to have ogpsd start gllin/open a serial port as
defined in the frameworkd configuration and then just us the Gypsy
DBus Interface to convey the standard information. The more advanced
stuff that is possible with UBX for example will be available in a
device specific interface, still got to think about the details.

Regards,
Daniel Willmann
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