Thank you to Peter Holzhauser for writing in and sharing with us his latest open-source project, 'ESPsoup'. Peter has written in previously to share his Android app, V2X2MAP, which detects and plots vehicle V2X (car-to-car) communications used by some modern cars. His new project, ESPsoup, combines an ESP32-C5 and a connected PC or phone into a fully featured scanner for the 2.4 GHz and 5 GHz bands.
ESPsoup has various features including a live spectrum view up to 80 MHz wide, a sweep mode to monitor larger bandwidths, a GPS-enabled heatmapping tool, Bluetooth analysis tools, an AirTag detector, WiFI analysis tools, a car-to-car V2X monitor, a smart home sensor reader, a drone remote ID detector, a microwave oven detector, and an analog FPV video demodulator and display.
The website notes that if you want to monitor multiple FPV drone video channels, up to eight ESP32-C5s have been tested to work together on a single USB hub connected to a PC.
Peter notes that he is planning to add RTL-SDR support to ESPsoup in approximately two weeks, so keep an eye out on their website for updates.
Thank you to Danny from brokensignal.tv, who wrote in and shared the release of his new project, 'ChronAlert'. Danny describes ChronAlert as "a free PC-based live dashboard for radio, weather, alerts, and other live information".
ChronAlert appears to be a situational awareness dashboard that combines multiple live feeds into one screen. It includes feeds like weather and emergency, ham radio & propagation, hazards & infrastructure, and local radio & tracking.
On the local radio side, we see that RTL-SDR is supported for receiving and tracking aircraft and ships via ADS-B and AIS, and for receiving APRS messages. The dashboard also supports Meshtastic radios, allowing users to see heard Meshtastic nodes and messages.
ChronAlert is free at the basic level, which allows 2 saved panels and 1 watch zone. A one-time fee of US$39.99 unlocks 10 panels and 10 watch zones, as well as various other features.
If you want more information, Danny has also published a detailed article with screenshots about ChronAlert on his blog.
ChronAlert: Weather, Ham Radio, Alerts & More in One Free Dashboard
Thank you to Patricio (LU5AKF) for sharing with us the release of HamRadioWeb.com's new FT8 WSJTx JTDX remote control Android app. Previously, we posted about HamRadioWeb's browser-based remote FT8 and FT4 receiver, and this Android app seems like a natural continuation of their software.
Patricio writes:
The app allows amateur radio operators to remotely control their JTDX or WSJT-X station from any Android phone or PC — no VPN, no port forwarding required.
What operators can do with it:
Monitor real-time FT8/FT4 decodes and band activity, just like sitting in front of JTDX or WSJT-X
Respond to CQ calls and transmit CQ remotely
Check where your signal is being heard via PSKReporter
Explore a worldwide activity map and a public DX spot page
Keep a contact log — auto-detected or manually added/imported
Follow community rankings and chat with other operators
The station connection is handled by a free Windows companion app (HamRadioWeb Companion) that links JTDX or WSJT-X to the user's account.
No radio at hand? The app opens in demo mode with simulated data so anyone can explore before creating an account.
Screenshots from the HamRadioWeb.com FT8 Remote Control App.
Thank you to Richard Didd for submitting his new software, 'OFFgrid-SDR', a fully offline RTL-SDR receiver program in an installer-free, single index.html file.
The OFFgrid-SDR program runs in any modern WebUSB-compatible browser, can demodulate common modulation types, and includes a spectrum and waterfall display, plus RDS, weather fax, and Morse code decoders. No internet connection is required to run it in the browser.
The program's advantage is that you can put the index.html file on a USB drive and use it portably on almost any machine with a browser. However, Windows users will still need to have installed the WinUSB drivers via Zadig first, and Linux users will need to blacklist the DVB-T drivers from taking over the dongle. macOS and Chromebook should just work without any additional steps.
The code is entirely open source and available on GitHub. More information about the project can be found on the project's GitHub.io page.
OFFgrid-SDR Screenshot
OFFgrid-SDR Demonstration with RTL card and Demo Mode
Thank you to 'magicint1337' for writing in and sharing with us a new program he's created called FernSDR. The author writes that FernSDR is an open-source WebSDR server rebuilt from scratch, based on feedback from WebSDR operators. It replaces his two previous programs, NovaSDR and PhantomSDR, the latter of which we covered in 2024.
A WebSDR program like FernSDR allows users to set up an SDR receiver on a remote device, such as a Raspberry Pi or PC, and access that SDR's data from anywhere in the world via a network connection. The author explains why FernSDR stands out:
What's different: a single binary with no dependencies and a one-line install on any Linux, an admin panel for everything (bands, updates with rollback, modules), day/night band switching by sunrise at the station, and modules for RTL-SDR (incl. Blog V4), RX-888 MkII and SDRplay, plus an FT8 decoder with PSK Reporter spots. In my lab tests against ten other WebSDR servers it had the lowest delay and memory use; the method and raw data are public.
Thank you to Viktor László (MusiThang on GitHub), for writing in and sharing with us his new project called sdrtop. sdrtop is a terminal-based SDR tool that is compatible with the HackRF and RTL-SDR. Viktor writes:
I bought a HackRF because I was curious how SDR works and found the whole topic interesting.
Later I wanted to understand what was actually in the radio signals, and I ended up writing a terminal tool for that. Along the way it grew RTL-SDR support too.
sdrtop is a bench instrument in a terminal: spectrum, waterfall, gain and clipping, lab-style readouts, and digital demodulation for measurement, not for listening.
I started it to learn the signal path. What it turned into is a gap I kept hitting: cheap SDRs used for real measurements over SSH, in tmux, or on a cyberdeck, where a heavy GUI just slows you down.
No audio on purpose. If RX stops, the numbers go stale instead of looking fine forever.
I care about being able to trust the numbers, so the signal path is written in Rust from scratch rather than sitting on a DSP library. The only external piece in that chain is the FFT crate. (rustfft).
On RTL-SDR it has native full support (R820T, E4000, R828D): single tuner gain + AGC, spectrum, waterfall, and the measurement panels the dongle can actually back. HackRF and tinySA are supported as well; Soapy is available in beta for other devices.
Written in Rust, open source, one-person hobby project, and still very much in active development. Classic Bluetooth is in progress; spectrum and lab are what I use every day.
sdrtop reminds us of a few previous terminal-based SDR programs such as sdrrat, as well as terminal-based ADS-B radar displays such as radar-tui and coole-radar.
Back in 2025, we posted about ESPARGOS, a phased array of many patch antennas, each connected to an ESP32 WiFi microcontroller. ESPARGOS could be used to determine the direction of arrival for WiFi signals and create a live augmented reality heatmap.
Recently, the ESPARGOS team has made an exciting discovery. They found that several ESP32 chips have an undocumented feature that lets the firmware bypass the fixed WiFi and Bluetooth functionality and instead capture raw IQ baseband samples. As a result, several ESP32 models can now be used as an internal SDR covering 2.2–2.7 GHz, plus 4.8–6.0 GHz on the ESP32-C5, with up to 80 MS/s sample rate and roughly 13–54 MHz of analog bandwidth, depending on the chip.
However, for use as a general-purpose PC-connected SDR, the output bandwidth is insufficient, so only snapshots of data can be exported to a PC. This means that the SDR will only work as a spectrum analyzer, and demodulating or decoding continuous radio data is not possible with just an ESP32. The exception is the new ESP32-S31, which can stream continuously at up to 16 MS/s over its Gigabit Ethernet interface, with a SoapySDR driver for GNU Radio and gqrx coming soon. If you want to try it yourself, the ESP-WebSDR page lets you flash the firmware to most ESP32 dev boards directly from your browser and view a live spectrum and waterfall.
Furthermore, ESPARGOS notes that phase-coherent IQ sample capture is now possible with their hardware. This means ESPARGOS is no longer limited to WiFi and Bluetooth signals; it can now perform direction finding on any arbitrary signal in the 2.4 GHz band. The team also says phase-coherent transmissions would be possible, but they aren't implementing them right now because they could be misused.
It also seems that, independently, at least two other projects discovered the same or similar features around the same time, but to solve different problems.
Over on Reddit, user /u/h0m3us3r discovered the same feature and uploaded it to GitHub on Sept 26, and recorded a video showing an ESP32-S3 working as an SDR with an FPGA used as a USB3 front end. Unlike ESPARGOS, h0m3us3r's project streams the raw IQ data to a PC continuously via the FPGA rather than in snapshots, so full demodulation/decoding on PC should be possible. However, the current prototype uses the FPGA to clock the ESP32, which results in poor phase noise. So if the clocking issues can be resolved, an ESP32 combined with an FPGA could make a standard general-purpose SDR, like the RTL-SDR, but with a 2.2–2.8 GHz frequency range and up to 80 MHz of bandwidth.
Another project that seems to be using a somewhat similar finding is C5VRX, which was first uploaded to GitHub on August 13. C5VRX uses an ESP32-C5 as a 5.8 GHz real-time FPV video receiver. Although this project appears to use a different mechanism, the result is similar: it uses an undocumented IQ data stream on the ESP32 to sample FPV signals and demodulate them onboard, outputting analog composite video through a simple resistor DAC. The project is still a work in progress and doesn't yet work reliably at range.
Thank you to Gerrit (PA3BYA) for writing in and sharing a hardware project he completed that combines an affordable optical encoder and a microcontroller with custom firmware to create a high-resolution USB mouse wheel for SDR tuning. Many people prefer using a knob to tune through the bands rather than a keyboard and mouse. Gerrit writes:
Although I initially developed it for use with the RTL-SDR, it is actually a general-purpose tuning solution that can be used with virtually any SDR software. Many SDR projects use a cheap mechanical rotary encoder with, for example, 24 pulses per revolution.
But why settle for a 24-pulse mechanical encoder when an affordable optical encoder can provide 600 pulses per revolution? For this quick SDR experiment, I combined a high-resolution optical encoder with a tiny Digispark ATtiny85 and turned it into a standard USB mouse wheel for tuning.
The result is a surprisingly simple and platform-independent tuning control that works with SDR software on macOS, Windows, Linux, and even a Raspberry Pi.
The encoder he used is a cheap Chinese part, costing around 17 Euros. However, one interesting issue that Gerrit encountered was that the cheap encoder would not reliably operate when powered from 5V, even though the operating voltage was specified as 5V to 24V. To fix this, he suspected that the input LDO was dropping too much voltage at the low 5V end, so he modified the encoder by shorting the input and output of the 78M05 regulator, to allow direct 5V power without any dropout.
His firmware for the ATtiny85 is open source and can be found on GitHub.
