Two open SDR drivers unlock MediaTek MT7921AU I/Q sampling
BirriaSDR and Mtk79ICAP both use the Wi-Fi chip's raw sampling capability, with different bandwidth, tuning and firmware approaches.
Two independent projects released open software-defined radio drivers for the MediaTek MT7921AU Wi-Fi chip in the days before October 18, 2026, both built on the chipset's raw I/Q sampling capability. The projects are BirriaSDR and Mtk79ICAP, according to Hackaday.
BirriaSDR streams raw I/Q samples from the MT7921AU to a host at 40 Msps with 14-bit resolution and tunes from 2156 to 2610 MHz. It talks to the Wi-Fi adapter over libusb, makes no permanent firmware changes, and offers an API similar to RTL-SDR's.
Mtk79ICAP takes a different route: it exposes the MT7921AU's sampling features through the SoapySDR interface, but requires firmware changes and a modified driver. It reaches a maximum bandwidth of 80 MHz and can tune to 5 GHz bands. With automatic gain control enabled, it can stream SDR data while the adapter works in monitor mode.
Earlier I/Q discoveries
About two weeks before October 18, 2026, an undocumented I/Q sampling feature was discovered in ESP32 chips, and similar features were subsequently found in other wireless chips, including LoRa and Wi-Fi chipsets. MediaTek's MT7996 had already been repurposed for SDR work, and some hackers have used the ESP32 to transmit arbitrary signals.
Quick answers
What frequency range does BirriaSDR cover?
BirriaSDR tunes from 2156 to 2610 MHz and streams raw I/Q samples at 40 Msps with 14-bit resolution.
Does Mtk79ICAP require firmware changes?
Yes. Mtk79ICAP requires firmware changes and a modified driver, and exposes the chip's sampling features through SoapySDR.
What is the maximum bandwidth of Mtk79ICAP?
Mtk79ICAP reaches a maximum bandwidth of 80 MHz and can tune to 5 GHz bands.