GPS Sight - why doesn't it work?

Marcus Bauer marcus.bauer at
Mon Apr 7 23:23:36 CEST 2008

On Mon, 2008-04-07 at 22:44 +0200, Torfinn Ingolfsen wrote:
> This reads from /tmp/nmeaNP, right?
> According to lsof it does:
> root at om-gta01:~# lsof /tmp/nmeaNP
> gpsd      1287 nobody    7u  FIFO   0,14      2797 /var/volatile/tmp/nmeaNP
> ld-linux. 1300   root   16w  FIFO   0,14      2797 /var/volatile/tmp/nmeaNP
> gpv       2222   root    5u  FIFO   0,14      2797 /var/volatile/tmp/nmeaNP

There is the problem already: /tmp/nmeaNP is a FIFO, = first in first
out. Only two processes should have it open, one that writes and one
that reads.

> If I do 'cat /tmp/nmeaNP, I get this:
> root at om-gta01:~# cat /tmp/nmeaNP
> $GPGGA,200855.54,,,,,00,00,3.0,,M,0.0001999,M,0.0090599,*5A
> $GPRMC,200855.54,V,,,,,,,070408,,,N*7D
         ^^^^^^            ^^^^^^
Looks good. The Neo has been long enough out to get the time from the
satellites, which is the first thing to happen - usually within seconds
of being outside.

> So the GPS is working, right?


If you are in between houses, it can take a couple of minutes till the
first fix. If there is mostly unobstructed view to the sky, it usually
takes 50 seconds to get a fix from the moment on that the time is

>From this sentence you need two or three in a row and between the commas
lots of values...

> I am using the /home/root/gllin/gllin script from the tangoGPS web
> page to start gpsd and gllin.

Have you been outside with tangoGPS for some minutes? As I said above,
you should either have GPS sight or tangoGPS running but not both at the
same time.

However you can have multiple programs running that use gpsd, i.e.
tangoGPS and gpsdrive.

If you use tangoGPS and gpsd then don't "cat /tmp/nmeaNP" but rather do:

  nc localhost 2947

then press 'r' and hit enter. Now you see all the NMEA messages passing

> One more thing: my Neo doesn't have a SIM card yet, but  that
> shouldn't mean anything for gps testing, right?

No prob.


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