Category: Amateur Radio

Gert KK6ZGA asked if I could set up an SD Card for her Raspberry Pi with including a few Amateur Radio apps. Rather than just install a bunch of random apps and hand it back, I thought it may be useful to document the setup steps for others as a reference in case anyone else is interested in doing something similar.

First steps, installing an OS – the SD card was blank, so first step I installed Raspbian from here: https://www.raspberrypi.org/downloads/raspbian/

… and then wrote the .img to the sd card with the dd util (notes on how to do this here , If on Windows there are utilities you can download to help you burn an image to an sd card, Google for help with these).

With my LG monitor it doesn’t recognize the HDMI output from the Pi unless you tweak the settings in config.txt to boost the output signal. I’ve covered this before here.

Booting up for the first time, the keyboard is configured by default for GB_en locale and UK keyboard layout (which makes it difficult to find some symbols on a US keyboard like ‘$’, so I have notes on how to switch this to US_en using raspi-config here.

For future reference, I have a number of other Raspberry Pi related getting started posts here.

Raspbian by default is configured to boot to a graphical desktop and to logon automatically with the default userid/password (pi / raspberry) – you should change your password on first boot. You can change this option in raspi-config too if you’d like to boot to a shell, or require logon at boot.

After first boot and the initial setup above, the list of apps I thought would be useful to install is most of what I covered in my July 2016 presentation at one of our RCARS club meetings on using a Raspberry Pi with  amateur radio. Here’s each of the apps I installed and how to start/use them:

• Installed xlog:
  • sudo apt-get install xlog
  • To start, double-click the icon on the desktop

• Installed cqrlog
  • sudo apt-get install cqrlog
  • To start, double-click the icon on the descktop

• Installed rtl-sdr for RTL dongle support:
  • https://www.kevinhooke.com/2014/07/26/installing-rtl-sdr-and-dump1090-on-a-raspberry-pi-to-receive-ads-b-signals/

There’s many things you can do with with RTL-SDR (you’ll need a RTL-SDR dongle to take advantage of these), so here’s a couple of examples. Most of these are command line only, from the Terminal, which you can open from the desktop here:

• dump1090 receives and decodes ADS-B transponder signals from airplanes flying overhead (depending on your antenna, within about a 100 mile radius) on 1.090Ghz. To run, there’s a couple of different modes.

‘Interactive’ mode is started like this from a terminal, first ‘cd dump1090’ then:

./dump1090 –interactive

You’ll see a display like this that updates every second, showing decoded info from received ADS-B transponder signals:

‘Net’ mode displays the received signals via a webpage. You’ll need the Pi to be on a network, either wired or wifi, and you’ll need to know your Pi’s IP address (which you can find by running ‘ifconfig’ in a Terminal). Run this with:

./dump1090 –net –quiet

And then point a browser at your Pi’s IP address on port 8080 (e.g. assuming your IP is 192.168.1.75, http://192.168.1.75:8080) and you’ll see the received signals plotted like this:

Received signals including latitude and longitude location info are plotted on the map, other signals with no location info are displayed in the table on the right.

Other things you can do with rtl-sdr utils: rtl_fm allows you to tune to a specific frequency and decode the FM modulation, and with a combination of piping the data to your audio out if you have speakers attached to the Pi’s audio output, you can receive FM signals and output the audio like this (scroll to the right for the whole command):

rtl_fm -f 96.9M -M wbfm -s 200000 -r 48000 | aplay -r 48k -f S16_LE

This tunes the RTL-SDR to 96.9Mhz, uses wideband FM, a sample rate (I think) of 200000, pipes the audio ‘|’ into aplay to play the audio stream. Take a look at the RTL-SDR docs here for more info on the options.

Hopefully this is a few things to get you started 🙂