Running the programs¶
We are now ready to run the demodulator and the decoder. Before we do that, though, we need to connect the radio and the antenna.
Connect the antenna’s connector to the LNA. Next, connect the LNA to the RTL-SDR dongle. Finally, plug the dongle into your computer’s USB port.
Running the demodulator¶
The demodulator needs a few parameters so it knows how to set up the tuner. The
demod-presets command makes this easier by providing presets for the known
frequencies. If you run this command without any arguments, you will get a list
of presets (among other things):
$ demod-presets Usage: /usr/local/bin/demod-presets PROFILE /usr/local/bin/demod-presets update parameters: PROFILE name of the tuner profile update fetch the latest profiles supported profiles: americas North and South Americas euraf Europe, Africa, Middle East apac Asia, Pacific
Pick a preset for your region and run
demod-presets again. For example,
let’s run it with
$ demod-presets euraf
Running the decoder¶
With the demodulator running, open up a new terminal window to start the decoder.
Output from the decoder will be logged in the terminal where you started it.
To run the decoder with paths different from the ones in this guide:
$ decoder -c /path/to/cache -o /path/to/downloads
Updating demodulator presets¶
The L-band presets used by
demod-presets command may change from time to
time. The program has an update feature which you can use to fetch the updated
presets. To use this feature, run:
$ sudo demod-presets update
It will take a while for the files to arrive, so please be patient. You may also need to adjust the antenna so it’s pointed correctly. Antenna pointing is outside the scope of this guide, though. The best place to ask for help regarding this is our forum.
When successfully downloaded, files should appear in the output directory. If
you used the values from this guide, that’s