radio

581 Articles

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.

Pager Converted To Meshtastic Node

October 14, 2026 by 10 Comments

Text messaging has been around on cellular networks en masse for around three decades now. It’s so common that it’s difficult to remember a time without it. Its two-way quick messaging is incredibly useful, but for even simpler communications there’s a one-way system that predates it. Pagers are able to receive simple messages, but outside of hospitals are rarely used nowadays. Eventually some added in two-way communications like this Motorola T900, but they’re still mostly obsolete. That’s why [zindustries87] converted it to operate on the Meshtastic network instead.

To get this pager working, a lot of reverse engineering was needed. There is essentially no documentation on the chips in these devices, so the screen and keyboard both were reverse-engineered to work with other hardware. In this case, [zindustries87] found space for a Heltec V4 with an ESP32-S3, a popular Meshtastic node with a small form factor. Some programming was needed to get everything communicating together, but from the looks of things it seems to have basic functionality.

[zindustries87] points out that this is a prototype, and didn’t know going in if the keyboard and screen could be brought back to life, or if the other hardware would fit in the case. But with it working on this level, they plan to add a number of other features in and possibly build a drop-in PCB replacement for these devices. They were once fairly popular so there are plenty around, and they’re a good form factor for a dedicated Meshtastic device that doesn’t need a smartphone to work. The only other ways of bringing pagers back to life involve bootstrapping an entire pager network, and Meshtastic is a bit more useful than that now.

WiFi Router Does Software-Defined Radio

October 12, 2026 by 5 Comments

Perhaps the most famous of software-defined radios is the RTL-SDR, which is very cheap because it’s a digital TV receiver that’s been pressed into service delivering raw I and Q data streams. But the RTL-SDR is certainly not the only chipset that can do this, and today we have a new one.

The MediaTek MT7996 radio chip in the Gemtek W1700K WiFi 7 router can serve as a very competent SDR receiver, and here’s [h0m3us3r] with the code to make it stream over Ethernet to a Linux machine with a web server, through the device’s SoC.

The radio works on the 2.4, 5, and 6 GHz bands, depending upon which version of the device — and thus which radio chip — you have. These may not be entirely useful to many who use lower bands, and given that a similar hack has been found for ESP32 radios on 2.4 GHz it’s likely a demand will arise for a receive up-converter. Until then, you can look at WiFi packets in a waterfall view to your heart’s content.

Since more and more devices now incorporate a radio, we hope that more such undocumented raw streaming modes will be found, and that we’ll see some other new SDRs. Something to look forward to.

Keep That Old Radio Alive With An ESP32

October 7, 2026 by 11 Comments

As the legacy AM broadcast bands fade away, what happens to the millions of devices built to receive them? Many of them will go into e-waste, but with a century of radios to choose from, some of them are collector’s items. Vintage tube radios like the ones [GarethDaviesLondon] has would go silent, so he’s made a small AM transmitter to keep them alive.

At its heart is an ESP32-S3, which takes an online radio stream and transmits it through RF generated with a pulse chain on a GPIO. Generating analogue signals from radio to video with a microcontroller is nothing new, but perhaps the more interesting part of this one comes in how he radiates enough from that pin. There’s a 3D printed box with stand-offs designed to take a widely spaced wire coil, which is enough for the vintage electronics to pick up. He makes the point that it may not be legal, but at that power we doubt anyone will notice.

The output on this one is 200kHz for the European long wave band, but we’re guessing a higher medium wave frequency could also be generated. Meanwhile if you are curious about AM, we’ve featured someone having a closer look at it.

A Mechanical Radio, Sort Of

October 1, 2026 by 40 Comments

[The Mike Stuff] has an interesting proposition. He asserts that ancient people like the Greeks could have built a form of radio that was purely mechanical. We aren’t sure we agree, but even if it were possible, we are sure it would have sounded awful. You can see the details in the video below.

The idea is that you can compress air with a waterwheel, blow it through a rotating disk with slots in it, and a valve to amplitude modulate the airflow through the disk. Horns like an old gramophone speaker would amplify the signal at both ends. The demodulation is straightforward and doesn’t even require power, like compressed air.

Continue reading “A Mechanical Radio, Sort Of” →

SDR– Lets You Patch Together Your Setup

October 1, 2026 by 15 Comments

It is often helpful to think of a radio as a series of interconnected functional blocks—hence the use of block diagrams to convey how a given radio operates. [Julian Haag] has brought this ethos to SDR–, a software-defined radio program where you can patch together your setup.

There are many software defined radio tools out there, with various interfaces and methods of configuration. [Julian] wanted to keep things intuitive and simple, and so built SDR– with an interface similar to that of a modular synth. You drop in blocks, like a radio, a demodulator, or a speaker, and then you link them together with patch cables to route the signals where they need to go.

[Julian] has populated the tool with plenty of useful decoders, too, so you can have lots of fun from the get go. You can play with things like ADS-B, POCSAG, SSTV, DAB, and RDS right out of the box. There’s also some fun passive radar and direction finding tools there too if you want to dive in. Files are on GitHub for the curious.

We’ve featured lots of neat SDR hacks over the years, like this neat real-time beamforming setup. Meanwhile, if you’re cooking up your own radio experiments in the homelab, don’t hesitate to let us know on the tipsline.