Gnss monitor

Experiments to extract and display GNSS live or recorded data

Screenshot

Required packages

Install Geographic library from https://geographiclib.sourceforge.io/C++/doc/install.html. Other libraries should be in the default repository.

libgeographiclib-dev
libpaho-mqttpp-dev
qt6-base-dev 
sudo apt install libgeographiclib-dev libpaho-mqttpp-dev qt6-base-dev

For Python install

pip install geographiclib

or

sudo apt install python3-geographiclib

Build

Code is found here (on SVN)

svn co svn://repos.gbar.dtu.dk/jcan/svnjca/projekter/gnss_receiver

The C++ code is then in qt/gnss_qt

Build by

cd gnss_receiver/qt/gnss_qt
mkdir -p build
cd build
cmake ..
make -j3

Run to create a configuration file

./gnss_qt

CMake problem

GeographicLibConfig.cmake

The find package

find_package(GeographicLib REQUIRED)

in cmake fails, as the file GeographicLibConfig.cmake is not found.

This can be fixed by renaming the provided file FindGeographicLib.cmake by

cd /usr/share/cmake/geographiclib
sudo ln -s FindGeographicLib.cmake GeographicLibConfig.cmake

XKB

Missing library, and CMake complains:

-- Could NOT find XKB (missing: XKB_LIBRARY XKB_INCLUDE_DIR) (Required is at least version "0.5.0")

The solution was to install

sudo apt install libxkbcommon-dev

This occurred on Raspberry Pi 5 using the 64-bit default OS.

Configure

After the gnss_qt is run the first time, there should be a default configuration file

[service]
logpath = log_%d/
; the '%d' will be replaced with date and timestamp (must end with a '/'). = 
max_logging_minutes = 60.0
log_service = true

[mqttin]
broker = tcp://10.59.9.201:1883
context = not used
clientid = ublox9_in
function = nmea/
system = ublox9/
log = true
print = false
use = false

[gnss]
input_use = true
input = /dev/ttyACM0
; input = ../../../log/log_mqtt.txt
log = false

[in]
; set 'saveconfig' to 'false' to avoid autosave = 
saveconfig = false
version = 2285 2025-06-26 07:20:46

There are two input alternatives:

• From a file (default may be '/dev/ttyACM0') or a logfile generated by the MQTT streamer for NMEA messages. Set 'input_use = true' to use this alternative.
• From a MQTT server that streams the NMEA messages. Change the IP in the [mqttin] group and change to 'use=true'. The NMEA messages are assumed to be in the payload of the message, and the subject as described (subscribing to 'ublox9/nmea/#').