MediaTek MT7921AU Wi-Fi chip gains two independent open-source SDR drivers
Two projects, BirriaSDR and Mtk79ICAP, have independently developed open-source drivers that repurpose the common MediaTek MT7921AU Wi-Fi adapter chip as a software-defined radio.
Summary
The undocumented I/Q sampling capabilities of the MediaTek MT7921AU Wi-Fi chip have been harnessed by two separate open-source projects released within days of each other. BirriaSDR streams raw samples at 40 Msps with 14-bit resolution across 2156-2610 MHz without modifying firmware, while Mtk79ICAP offers a SoapySDR-compatible interface with up to 80 MHz bandwidth in 5 GHz bands but requires firmware and driver modifications. Both projects follow recent similar discoveries in ESP32 and other wireless chips.
How the two drivers differ
- BirriaSDR: libusb üzerinden doğrudan register erişimi; kalıcı firmware değişikliği yok; 40 Msps, 14-bit, 2156-2610 MHz; RTL-SDR benzeri API
- Mtk79ICAP: SoapySDR arayüzü; firmware ve driver modifikasyonu gerekli; 80 MHz maksimum bant genişliği, 5 GHz bandı desteği
- Mtk79ICAP unique feature: Wi-Fi monitor modu ve SDR veri akışı eşzamanlı çalışabiliyor (otomatik kazanç kontrolü açıkken)
- Donanım bağlamı: MT7921AU, harici anten konnektörüne sahip USB Wi-Fi adaptörlerinde sıkça kullanılıyor, frekans mikser devresi bağlamayı kolaylaştırıyor
Why it matters
The rapid emergence of multiple independent SDR drivers for commodity Wi-Fi chips, following the ESP32 I/Q discovery, suggests a growing pattern of undocumented radio features being unlocked in mass-market hardware. This lowers the barrier for SDR experimentation and could expand the pool of affordable, readily available hardware for radio research.
Original reference: hackaday.com →