On 20.09.13 23:30, [email protected] wrote:
> people run navit on very slow arm5 WinCE devices and it does generally work
> quite well there. So raw CPU power is not the problem.
> Lock on roads did cause some speed issues that were so severe that the program
> appeared to hang on these slow devices, do not remember the details but
> probably
> worth a try.
I am convinced that navit can do better on G4 hardware, its probably a
poor tuning of some parameters. A "Car simple" worked quite good too,
so I'll take that and add as much complex scenery from "Car" as I can
until performance starts dropping.
Last time I reported some paramters I intend to experiment; I haven't
done it till today because in the meantime I had to return the gps
receiver to the manufacturer due to obvious firmware/software bugs. I
decided to wait until ublox-7 based USB receivers appear (eg. Navilock
or such).
>> Then, it looks like the kendau mg220 gps receiver outputs some 10 nmea
>> sentences per second (half of them are GPGSV and GLGSV), and only once
>> per second come GPGGA data. What else besides these is necessary for
>> navit operation? How to turn off others?
>
> just one position message per second? Not sure if that will be enough for
> car navigation.
Yes, once per second: it did output GSA, GSV (for each visible
satellite, i.e. 10-12 sentences), GLL, GGA, RMC, VTG sentences once in
second. (Maybe too much for a 9600bps 8N1 RS232/USB-connection?)
Anyways, as navit apparently only uses GLL and VTG, everything else can
be turned off and then the transfer rate increased. Further, as 50 kmh
city speed is 13.8 m/s so 13 metres is an unavoidable lag at 1Hz
positions rate if navit does not implement some velocity prediction and
use that instead while painting the map?
JFYI: The receiver was MT-3333 based, and $PMTK605*31 returned
$PMTK705,AXN_3.20_333_13042200,331C,MC-GG,*70
As next I'll try to take a look at OpenGL renderer besides QT4-based
graphics (not that I suspect QT4 being too slow). MacOSX 10.4 has
standard OpenGL+GLUT installed by default but the ./configure-script
does not find that. Then, I use the standard 'say' OSX-command for
speaking purposes, don't know yet if this can be tuned too (or see if
navit gets faster if turning off the "speaker").
Eeri Kask
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