[gpsd-users] Fixes coming too late (great lag)

[Lisandro Damián Nicanor Pérez Meyer]

Hi! I have just hitted a strange issue using Debian's gpsd 3.16-4, although 
I'm pretty sure I am the culprit.

The issue is the following: I am using gpsd trough libgps. My GPS device is 
sending data @10Hz (please take a look at the notes below). If I use xgps or 
gpsmon I can see the data comming and the apps updating the information as 
they should, ie, if I move lat and long get changed as expected.

Now on my app I use:

result = gps_open("localhost", 37455, &mGPSData);
[check result...]
result = gps_stream(&mGPSData,WATCH_ENABLE|WATCH_JSON, NULL);
[check result...]

And with a timer I check every 80 ms for a fix:

    if(gps_waiting(&mGPSData, 500))
    {
        int result = gps_read(&mGPSData);

        if(result == -1)
        {
            [handle this]
        }
    }
    else
    {
            [handle this]
    }

Now if I start to move I need to wait like 60 seconds to see the coordinates 
changing. In other words, I have a great lag. But I can't reproduce this with 
xpgs nor gpsmon, so I must be doing something wrong here.

Notes: I'm receiving data trough CAN but not using NMEA200 because I receive 
other info there, so the data gets consumed by a muxer and then sent to and 
UDP port in which gpsd listens. It clearly works because I then attach xgps 
and gpsmon there and get the expected result.

So, what am I doing wrong here?

Thanks a lot in advance!

-- 
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    Damian Nadales
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Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/

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