If you’ve been on the RTL-SDR forums lately you may have seen that a lot of work has been going into the DragonOS software. This is a software-defined radio group that has seen a lot of effort put into a purpose-built Debian-based Linux distribution that can do a lot of SDR out of the box. The latest and most exciting project coming from them involves a method for using the software to receive and demodulate analog video.

Decoding 5GHz NTSC Video from Drones with a HackRF, DragonOS and SigDigger
https://www.rtl-sdr.com/decoding-5ghz-ntsc-video-from-drones-with-a-hackrf-dragonos-and-sigdigger/

With the ESP32 series of microcontrollers having had hidden software-defined radio (SDR) facility revealed, we’re now moving on from the announcement into projects making use of the finding. [Twotoz] has one using an ESP32-C5, to receive and demodulate analog FM video.

You might think that video is something which has largely gone away in 2026, with TV transmissions having made the switch more than a decade ago, and home entertainment appliances having used HDMI for longer. But it’s still very popular in the world of drones however, where it exists as 5 GHz FM transmission.

Analog 5.8 GHz FPV receiver on one Seeed Studio XIAO ESP32-C5 with a passive 6-bit resistor DAC: live FM video in, composite PAL/NTSC out for goggles.
https://github.com/Twotoz/C5VRX

C5VRX-5 uses one live demodulator.

U85Q demodulator in the TX BitScrambler: an untrained 32-phase tracker that keeps the picture locked across VTX deviations, off-centre carriers and multipath instead of dropping out. Board-validated on real video.
Fixed ultrafine IQ (ADC bits 9,6,5,4) at 40 MS/s, no CPU in the sample path.

To quote commenter [douyarou], “It’s like our little version of a Precambrian explosion”. A bunch of hackers have discovered, independently and building on each other’s work, software-defined radio (SDR) capabilities in more places than you can shake a stick at.

It all started with [Espargos] and [h0m3us3r] apparently independently discovering that the ESP32 family of chips had a “secret” debug mode that allowed direct access to the radio that’s normally used for WiFi. While the 2.4 GHz radio signal is almost always immediately converted into data by the MAC hardware, here they found a way to listen in upstream, to the raw IQ data.

Since the discovery of an undocumented I/Q sampling feature in ESP32 chips about two weeks ago, there’s been a flood of similar features being found in other wireless chips, including LoRa and Wi-Fi chipsets. The latest chip to join their ranks is the MediaTek MT7921AU, often used in Wi-Fi adapters, with two different projects developing independent SDR drivers for it in the last few days.

The first was BirriaSDR, which discovered that the chip exposes raw I/Q samples for debugging and calibration; BirriaSDR instead streams these to the host at 40 Msps in 14-bit resolution, with the option to tune from 2156 to 2610 MHz. BirriaSDR uses libusb to directly communicate with the Wi-Fi adapter and access its registers; it doesn’t make any permanent firmware changes, so the Wi-Fi adapter goes back to its original state after being used as an SDR. BirriaSDR implements an API similar to the RTL-SDR’s.

Mtk79ICAP, by contrast, exposes the MT7921AU’s sampling features over a standard SoapySDR interface. Unlike BirriaSDR, it applies some firmware changes to the chip, and it requires a modified driver to work.

https://github.com/luigifcruz/birriaSDR

BirriaSDR

Turn a supported USB Wi-Fi dongle into an experimental SDR receiver with 14-bit I/Q at 40 MSps complex.

BirriaSDR ships as libbirriasdr, a C11 library with an API modeled on librtlsdr, together with a command-line recorder. It talks to the device from userspace through libusb and includes the source of its own small device program. Start with Build and try, or jump to the API to add the receiver to an application. To see it working without building anything, try the rough proof of concept.

Important

This is experimental software. The tested board starts from a channel 6 initialization profile, and the library can tune anywhere from 2156 to 2610 MHz. Sensitivity across that range, frequency accuracy and gain are not calibrated. Use at your own risk.

Bridge the gap between SDR experiments and real wireless prototypes, enabling new PHY algorithms to be tested in a working RF system.

https://hackaday.io/project/205674-building-a-real-world-sdr

The news of the past couple of weeks has seen the ESP32 turned into an software-defined radio (SDR) thanks to a hidden baseband mode, an exciting development by anyone’s standards. It seems unexpected SDRs are like busses in that you wait for ages and two turn up at once, because hot on the heels of the ESP32 story is [Samson1te], revealing the SDR functionality hidden within the LR2021 LoRa chip. This one is especially interesting because as well as a 2.4 GHz radio, the chip sports a radio that works from 150 to 960 MHz.

https://github.com/SAMS0N1TE/lr2021-sdr

LR2021-SDR

A LoRa chip that tunes from 100 MHz to 2.74 GHz and streams 16-bit I/Q.

P25 voice, pagers, FM, Bluetooth LE and custom transmit from the Semtech LR2021 on a handheld, with no SDR dongle.

Perhaps the most exciting news of the past few weeks in the world of hardware hacking has been the unlocking of hidden SDR functionality in the Wi-Fi radios found on Espressif ESP32 microcontrollers. They can be used as both transmit and receive SDRs, and given that it’s early days for this hack we expect that great things are yet to come.

There’s one snag though, despite speculation that they might be dragged down to much lower frequencies, as far as we know they’re only proven to work around the Wi-Fi frequencies. Though the reality may be wider we’ll take that for a 2.4 GHz part as a 100 MHz slice from 2.4 GHz to 2.5 GHz. Plenty of possibilities there, and they might even work down to 1.8 GHz, but there would be so much more to do if it could work elsewhere in the spectrum. So it’s time to look at the converter, a tried and tested old way to make a radio work on a different frequency.

The ESP32, An SDR In Itself
https://hackaday.com/2026/10/03/the-esp32-an-sdr-in-itself/

Generally the DVB-S and -S2 standards require a satellite somewhere in Earth orbit to provide a signal to receive, but you can also transmit your own DVB-S2 stream with any RF transmitter if you’re so inclined. Courtesy of recent breakthroughs in using the RF hardware of the ESP32 on a raw level, [SP8ESA] has created the ESP32-DATV project using which you can broadcast a DVB-S2 signal using an ESP32-C3.

While a host PC side application handles the heavy lifting of turning the input video signal into a DVB-S(2) compliant signal, it is the ESP32-C3 that prepares the samples for transmission before sending them off to its RF block, with no external hardware needed.

If this brings to mind the idea of using an off-the-shelf DVB-S2 receiver to play back the signal, the frequency range for DVB-S2 is 10.7 – 12.7 GHz, while the ESP32-C3 is limited to roughly 2.4 GHz courtesy of it targeting only 2.4 GHz Wi-Fi and Bluetooth signals.

https://github.com/SP8ESA/ESP32-DATV