A pocket SDR scanner that I probably shouldn't carry around

STM32 driving an RTL-SDR in a 3D-printed grip. Battery life is honest. Reception is suspicious.

The pitch: an RTL-SDR dongle, an STM32, a small OLED, a rotary encoder, and a 18650 battery in a 3D-printed grip. The whole thing fits in a coat pocket. The whole thing also gets warm enough in a coat pocket that I should probably reconsider its location.

The radio side

The RTL-SDR does the heavy lifting. The STM32 talks to it over USB host mode and pulls samples down at a rate that is honestly more than the OLED can usefully visualise. Most of the firmware is just averaging.

The grip

Printed in matte black PETG, with brass heat-set inserts because I am tired of stripped threads. There is a strap loop because I have dropped it more than once.

Should you build one?

Probably not. It’s a fun build but a commercial SDR-in-a-box is cheaper and works better. Build it anyway, obviously.