Using a low-cost Raspberry pi enabled Gnss reflectometer to log and upload NMEA messages

Instructions for building together the casing

Using the NMEA logger

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Install this python module from the repository root directory

pip install .

Copy and Change the yaml config file

The file nmeaconfig.yml is the file used for configuration. Copy the file to the user's home and open it with a text editor and change the value.

• file_base ex: myfile, the basename used for naming the output (date and increment will be appended to this e.g. providing testname will result in testname_2022-01-01_00.gz
• data_dir ex: /home/user, the path where the data logs will be stored
• device ex: /dev/ttyAMA0, the linux serial device path which produces the nmea output
• baudrate ex: 9600, the baudrate of the serial port
• serialsleep ex: 20, set the amount of microseconds to sleep between serial reads (this time will be made available to do other tasks such as uploading)
• webdav
  • url Webdav upload address
  • user
  • password

How to setup a service file

If you want your raspberry to automatically launch the logger on boot, you need to create a service file (see the example file nmealogger.service. This allows to simply plug your raspberry and directly execute a program without having to open a terminal. This is very useful for field survey where the raspberry boots and runs without interactive user input, or where a power failure will result in a reboot.

Now to create the service, copy the modified nmealogger.service file into the right directory:

sudo cp nmealogger.service /etc/systemd/system/nmealogger.service

Make sure to replace User with a user who can access the serial port and the data_dir provided in the configuration file Before starting the service, execute the following line. It reloads to take the change into account

sudo systemctl daemon-reload

You can then start the service, if the service file is installed in the right directory (/etc/systemd/system/)

sudo systemctl start nmealogger.service

You can see if your service file is properly running by executing

sudo systemctl status nmealogger.service

You can also of course stop the service

sudo systemctl stop nmealogger.service

Your service file is now running on your raspberry until the board is shutdown. If you want to start it on boot enable it:

sudo systemctl enable nmealogger.service

Authors

Lubin Roineau, Roelof Rietbroek