Re: [gpsd-users] gpsfake question

[Joshua Quesenberry]

Gpsd Users,

I'm using gpsfake like this: gpsfake -l -c 0.05 test.nmea

I chose those options so I could a) see the lines printed to the screen as they 
were sent to the daemon and b) a rate of 20 Hz since my data is captured at 10 
Hz and a GPGGA and GPVTG string for each period.

For observing the data I was hoping to see updates using cgps. I also tried 
viewing updates using the gpsd client node in ROS. Neither of these methods 
show me data actively changing. Using cgps I see latitude, longitude, and 
altitude update at least once, however, time, heading, speed, etc. are missing 
and if I stop cgps and reopen it then everything is missing. Using gpspipe -r I 
do see strings printed to the screen that appear to be what gpsfake is sending 
out.

I used http://freenmea.net/decoder to test a couple of the strings in my file 
and they all appear correctly formatted. Again, my file only contains GPGGA and 
GPVTG strings. In those strings I'm setting timestamp (using current UTC time), 
latitude, longitude, altitude, course over ground (heading), and speed 
variables with route data I've collected. I'm hard coding fix type to 1, number 
of satellites to 9, and hdop to 0.87.

Here's an example of my data.

Input File (test.csv):
Timestamp,Latitude,Longitude,Elevation,Heading,Speed(m/s)
2487,38.897666,-77.036533,611.8,270.0,15.013000104

Output File (test.nmea):
$GPGGA,004828,3853.8600,N,07702.1920,W,1,09,0.9,611.8,M,0.0,M,,0000*63
$GPVTG,270.0,T,,M,29.2,N,54.0,K*6D

Are there additional NMEA strings I need to send out? My understanding is that 
GPGGA and GPVTG has the majority of what is needed for basic navigation.

Thanks!

Josh Q

-----Original Message-----
From: Gary E. Miller [mailto:address@hidden 
Sent: Wednesday, May 10, 2017 3:14 PM
To: Joshua Quesenberry <address@hidden>; gpsd users <address@hidden>
Subject: Re: gpsfake question

Yo Joshua!

On Wed, 10 May 2017 12:57:26 -0400
"Joshua Quesenberry" <address@hidden> wrote:

> I assume you know how to use gpsfake?

Sort of.

> I'm trying to run a simulation, however, when I run cgps the data is 
> not updating. Can you look at the format of my data and tell me if I'm 
> doing something incorrect? I ran a portion of the data through 
> http://freenmea.net/decoder and it's looking good there.

> Any helpful hints that might explain why it's not working?

Two things: 

1) best to post questions like this to gpsd-users, many people know gpsfake 
much ebtter than I do.

2) What's not working?  You made no mention of how you are using that data 
file.  How did you start gpsfake?  How did you look at the results of running 
this file in gpsfake?

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin