Build a portable RTL-SDR frequency scanner using a Raspberry Pi, RTL-SDR, and a 3.5" display

Research
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Here’s the finished product first

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What you’ll need

  • A Raspberry Pi
  • A 3.5-inch display
  • An SDR receiver
  • Your brilliant brain

If you need a 3.5-inch screen mirror, contact me. Flashing the official website image directly will result in a weird resolution (probably).

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Let’s get started

After flashing, remember to enable SSH to your network (recommended: systemctl enable ssh), which makes operations easier.

Then remember to update your software sources. We recommend using the official source, but using a Chinese Raspberry Pi source is also acceptable.

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Here’s the official source to avoid getting lost.

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deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
# Uncomment the line below, then 'apt-get update' to enable 'apt-get source'
#deb-src http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi

First, install the dependencies.

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sudo apt-get update sudo apt-get install git cmake build-essential python3-pip libusb-1.0-0-dev libsdl2-2.0-0 libatlas-base-dev librtlsdr0

Then install some Python modules.

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sudo pip3 install numpy pygame -i https://pypi.tuna.tsinghua.edu.cn/simple some-package
sudo pip install pyrtlsdr -i https://pypi.tuna.tsinghua.edu.cn/simple some-package

Go to the repository https://github.com/adafruit/FreqShow and clone it to your Raspberry Pi.

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cd ~
git clone https://github.com/adafruit/FreqShow.git
cd FreqShow

Note the installation of rtlsdr Otherwise, you’ll get some strange errors.

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apt-get install libusb-1.0-0-dev git cmake
git clone https://github.com/rtlsdrblog/rtl-sdr-kerberos.git
cd rtl-sdr-kerberos
mkdir build
cd build
cmake ../ -DINSTALL_UDEV_RULES=ON
make
make install
ldconfig

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Here’s a tip from the author:

If using the official 7” Raspberry Pi Touchscreen instead of a PiTFT, edit the file freqshow.py and comment out the following lines as shown (starting around line 73). Do NOT do this if using a PiTFT!

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#os.putenv('SDL_VIDEODRIVER', 'fbcon')
#os.putenv('SDL_FBDEV', '/dev/fb1')
#os.putenv('SDL_MOUSEDRV', 'TSLIB')
#os.putenv('SDL_MOUSEDEV', '/dev/input/touchscreen')

In essence, if you’re not using the PiTFT as your display, you need to delete the above lines of code in freqshow.py.

Once everything is ready, simply run python freqshow.py That’s it

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Demonstration video

References