Radio Hacks

1517 Articles

5 GHz Drone Video, With An ESP32

October 20, 2026 by 30 Comments

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. There’s no digital cliff-edge to lose your picture if you fly into somewhere with bad propagation of radio waves, and perhaps more importantly, it has an extremely low latency. This receiver uses a Seeed Studio Xiao ESP32-C5 board with a simple resistor-ladder DAC to produce the video. It has a simple button channel interface, and a serial link for more in-depth options.

It’s good to see these projects appear, especially as this one’s 5 GHz and shows those chips work too with the hack. We’d be interested to know whether the latency of the SDR affects its usability though. You may be interested to know this isn’t the first time we’ve seen an SDR do video.

Thanks [Ink] for the tip!

Going Whole-Hog On A First Satellite Ground Station

October 20, 2026 by 7 Comments

When most radio enthusiasts start trying to pick up signals from satellites, they might put together a quick-and-dirty Yagi antenna and try to catch a repeater as is passes overhead, or they might grab a small unused dish from a satellite TV service and point it up at a weather satellite by hand to try to decode some of the data coming down. But [Cranktown City] had a different approach. He found an eight-foot dish online and built a massive articulating base station out of it as his first exploration into the world of satellites.

The first problem that needs to be solved with a dish of this size is its mounting location. This installation uses a large post and concrete foundation with a custom-fabricated metal base at the bottom. The metal base houses all of the electronics not just for receiving signals from the dish, but also for orienting it properly. That includes a large metal gear driven by a wheelchair motor to control its azimuth and a linear actuator to take care of its elevation. Getting the large dish onto the frame was its own ordeal, complicated by the fact that it’s not uniform in its shape and has to be mounted in a specific orientation.

With everything assembled, the circularly-polarized antenna installed, and the computers up and running, the dish is able to track satellites across the sky and download data from things like GOES weather satellites. [Cranktown City] also built in a system that detects wind and points the dish vertically when it goes above a certain speed. This level of effort is impressive, and absolutely not required to listen in on plenty of sattelite activity out in the sky, but this installation will certainly give [Cranktown City] a lot of mileage and possibly even work for some radio astronomy.

Continue reading “Going Whole-Hog On A First Satellite Ground Station” →

Meshtastic Sniffer For DragonOS

October 19, 2026 by 1 Comment

Meshtastic has gained a lot of popularity over the last few years thanks to its low barrier of entry. No licenses are needed and the hardware is dirt cheap, at least when compared to a lot of ham radio gear. But while that physical barrier is low, there is a bit of a learning curve. Part of that comes from the fact that there are a lot of channels and modes that people could be communicating on, and unless the user knows that information up front it can be hard to find where the conversations are happening. [cemaxecuter] noticed this problem and built a Meshtastic sniffer into his radio-forward Linux distribution, DragonOS.

The sniffing software is built in C and comes as a complete standalone binary and does not rely on GNU Radio. With DragonOS up and running and the software loaded, it can look at the entire bandwidth that Meshtastic operates on and detect any traffic and decode it (as long as the key is known). [cemaxecuter] is using a HackRF as a software-defined radio for this project, which he notes doesn’t quite have enough bandwidth to cover every Meshtastic operating frequency, but it can get most of them. After firing up his own node, the software quickly detects it and shows its details in the terminal.

Software like this opens up a lot of opportunities for things that would be tedious, difficult, or impossible to do with with a standard Meshtastic node. Besides finding places where conversations are happening more easily, [cemaxecuter] also suggests that it could be used for wardriving and for locating or finding other networks much more easily. For those who still haven’t tried it out, take a look at this 2023 treatise on the protocol and hardware and then dive right in.

Continue reading “Meshtastic Sniffer For DragonOS” →

A waterfall display is shown, with a prominent yellow block in the upper right corner of the display.

Turning A Wi-Fi Adapter Into An SDR

October 18, 2026 by 9 Comments

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. However, it can reach a maximum bandwidth of 80 MHz and tune to the 5 GHz bands. The Wi-Fi adapter in use can also simultaneously work in monitor mode and stream SDR data, though this only works when automatic gain control is enabled.

This is the second MediaTek chip we’ve seen repurposed for SDR work, after the earlier MT7996. Conveniently, Wi-Fi adapters often have external antennas, which should make it easier to connect a frequency mixer circuit. These adapters aren’t quite there yet, but some hackers have already used the ESP32 to transmit arbitrary signals.

Discovering SDRs Everywhere

October 17, 2026 by 26 Comments

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.

Seeing this, folks were immediately inspired to find out if they could transmit as well. [marble] not only got transmit functionality working, but integrated the part in with the standard osmosdr data flow, which meant that a whole bunch of existing tools were ready to go. We didn’t know about it at the time, but apparently [jochenhammes] and [z1000biker] concurrently had their TX-capable hacks up and running: here and here.

At this point, folks have already started to use the capabilities for broadcasting digital TV signals, voice signals, FM Hell, and other hijinks. This reminds us of the early days of the RTL-SDR project, when a competent, if receive-only, SDR functionality was found in a bunch of USB TV-tuner dongles. Once the hardware capabilities were sussed out, people started writing all sorts of useful software, and it gave rise to all manner of radio projects, from simply poking at domestic wireless devices to tracking all the airplanes in the world as they fly by.

[Tom] and I were discussing this on the podcast, and he remarked that of course there are SDRs hidden everywhere there is a radio unit these days, and the question is just whether or not we could hack them into usability. And before the podcast was even finally edited, [Samson1te] told us about his find in the LR2021 LoRa chip. This is a radio that’s designed to be a radio, with 16-bit resolution, and covering lower frequencies from 150 MHz to 960 MHz.

Compared to the RTL-SDR revolution, this is all happening at incredible speed. Each of these hacks will enable us to use different slices of radio spectrum with different degrees of ease, but it’s clear that the cost of entry into playing around with digital radio has just dropped precipitously. We will see hundreds of new signals hacks in the next few months – the floodgates have been opened.

This article is part of the Hackaday.com newsletter, delivered every seven days for each of the last 200+ weeks. It also includes our favorite articles from the last seven days that you can see on the web version of the newsletter. Want this type of article to hit your inbox every Friday morning? You should sign up!

Another Wireless Chip Has A Hidden SDR Revealed

October 15, 2026 by 18 Comments

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.

We’re indebted to them for posting this in a comment on our receive converter post, as a complimentary project to the ESP32 one. It gives a 16-bit SDR with receive and transmit, however as with the ESP32 it’s early days and we hope great things lie ahead. There are comprehensive docs available, should you wish to enter the fray. Currently the main demo is P25 digital voice.

If you’re interested, you can follow our coverage of the ESP32 SDR.

So You Want To Make Your SDR Work On Other Frequencies

October 15, 2026 by 24 Comments

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.

Continue reading “So You Want To Make Your SDR Work On Other Frequencies” →