Luigi Cruz has published BirriaSDR on GitHub, a project that turns a USB WiFi dongle into an experimental SDR receiver with 14-bit I/Q at 40 million complex samples per second. The tested hardware is a COMFAST MT7961/MT7921AU dongle, pairing an MT7961 digital die with an MT7972 analog die.

WiFi chips already contain a wideband receiver, and some include an internal I/Q capture engine meant for calibration and debugging. BirriaSDR repurposes that path. The host programs the front end and capture engine through their registers, and a 1,632 byte device program, loaded through the chip’s boot ROM, ships the samples to the host over USB. No vendor firmware is downloaded, and nothing is written to flash or eFuse, so all configuration disappears at power off.

The code ships as libbirriasdr , a C11 library with an API modeled on librtlsdr , plus a command-line recorder. It tunes 2156 to 2610 MHz and 4500 to 6200 MHz, including while streaming.…