Have you ever wondered what's in the radio waves zipping invisibly around you every day? Software-defined radio (SDR) is a great tool to explore radio signals using a computer and inexpensive radio tuner. With SDR you can examine many radio signals such as FM radio, television, emergency & weather radio, citizen band (CB), wireless protocols and much more.
Although dedicated SDR hardware like the HackRF allow you to tune an immense range of the radio spectrum, you can easily get started with SDR using a Raspberry Pi and inexpensive RTL-SDR tuner. Inspired by the HackRF PortaPack, this project will show you how to build a small portable SDR scanner using a Raspberry Pi, PiTFT, and RTL-SDR radio dongle. With the Raspberry Pi Freq Show RTL-SDR scanner you can visualize the invisible world of radio!
UNDERSTAND: FREQSHOW DOES NOT PLAY AUDIO. It graphs the frequency and amplitude of RF signals, which can be useful for troubleshooting and developing a basic understanding of radio and wireless protocols, but it does not decode nor demodulate them.
Before you get started it will help to familiarize yourself with a few other guides for more background information:
- Circuit Playground: F Is For Frequency
- Getting Started With RTL-SDR and SDR#
- FFT: Fun with Fourier Transforms
- PiTFT 3.5" Touch Screen For Raspberry Pi
- Raspberry Pi: Using SSH
Also for some inspiration on what you can do with SDR, check out these excellent presentations from previous DEF CON conferences: