In my previous post on raspi-projects, I outlined common approach of installing drivers for rtl-sdr devices. Since, we now have a working rtl-sdr device configured to run with raspberry pi computer, we are all set to use it to visualize whats going on in the air by scanning different frequencies. To do so, I am going to use some open source application named Gqrx. Gqrx is an open source software defined radio (receiver) based on the GNU Radio (a Free & Open-Source Toolkit for Software Radio). Please, follow the given steps for installing Gqrx and scanning signals in different frequencies. Also, check the official site if you need more information on the raspberry pi variant of the software. The following installation instruction is also referenced from the same site.
Note if you have not yet installed rtl-sdr drivers please check my post on Rtl-sdr in Raspi
First, let’s install dependencies and wget (non interactive network retriever package ) if it is not already installed, and just initiate the down loader to get he source. Please continue with the following command:
# Install dependencies
sudo apt update
sudo apt install gnuradio libvolk1-bin libusb-1.0-0 gr-iqbal
sudo apt install qt5-default libqt5svg5 libportaudio2
# Update or install wget
sudo apt-get install wget
# retrieve the gqrx-sdr software
wget https://github.com/csete/gqrx/releases/download/v2.11.5/gqrx-sdr-2.11.5-linux-rpi3.tar.xz
# Extract the tar file
tar -xvf gqrx-sdr-2.11.5-linux-rpi3.tar.xz
# Now, to enable access to USB devices like rtlsdr, Airspy,
# SDRPlay, etc, you need to copy the corresponding udev rule to
# /etc/udev/rules.d/.
# first go to the extracted directory
cd gqrx-sdr-2.11.5-linux-rpi3
# copy the corresponding udev rule files
sudo cp udev/*.rules /etc/udev/rules.d/
# simply run the gqrx from the folder to run the program
./gqrxNOTES
- If everything was setup correctly, you must see GUI screen of the program.
- After the GUI is loaded simply select your rtl device (Realtek RTL2338… in my case) from the Configure I/O Devices dialog box (if it doesn’t pop-up find it from File–>I/O devices)
- After that simply press the play button on the top left side of you GUI toolbar.
- You should see some signals being received. Play with the software and try scanning FM, AM radios, or even unencrypted code-less phone signals (cell phones signal are encrypted, might not be easier to decrypt), air traffic control communication, NOAA satellite signals and may more.. Be patient and explore..
Note that, all the post in this website are kept and preserved for my personal reference as an online notebook, and therefore typos and other mistake might be frequent.
Also, be aware that scanning and transmitting any signal might involve legal issues, please use it at your own risk and responsibility.