A pocket RF detector people could actually learn on
An ESP32-based radio-frequency power detector, built as a conference badge and taught as a four-hour hands-on direction-finding workshop at DEF CON 34.
The problem
Direction finding is taught badly. Most introductions either hand you a spectrum analyser you cannot afford or a toy that lights up near a microwave and teaches you nothing about how radio actually behaves. The gap is a device cheap enough to give away and honest enough to learn from.
What it is
A wideband RF power detector on an ESP32-C3, using an AD8317 logarithmic detector, packaged as a wearable badge with an on-board display. It reads received power and shows it live. It is built on RFHunter, an open-source project licensed under GPL-3.0, and the attribution travels with the hardware and the firmware.
The honest part
The AD8317 produces a scalar power reading. It does not compute a bearing. Any direction you get out of this device comes from your own sweep technique: you turn, you watch the number, you learn what a null looks like. Stating that clearly is the whole pedagogical point, and it is also why the workshop is four hours instead of forty minutes.
How it was taught
Co-presented as a hands-on workshop at DEF CON 34. Attendees built understanding by hunting actual transmitters in a hostile RF environment, which is the least forgiving classroom available and therefore the most useful one.
Limitations
This is a detector, not a receiver. It tells you energy is present and roughly how much. It does not demodulate, classify, or identify. It has not been characterised against calibrated reference equipment, and no accuracy figure is published because none has been measured under conditions worth publishing.