Thank you to Julian for writing in and sharing with us his interesting project called SDR-- (SDR minus minus). SDR-- is an open-source app that lets you wire devices, decoders, and displays together on a desktop window or browser-based canvas. It is described as "a software-defined radio application with a visual signal path. Connect devices, decoders, displays, and recorders on a canvas, then pin the controls you use to a rack."
A separate Rust server, which can sit on the same PC or a remote computer (like a Raspberry Pi), handles the DSP. Julian notes that SDR-- has native RTL-SDR support, and decoders for ADS-B, AIS, POCSAG, FT8, SSTV, and RDS are already implemented, with more in progress. The app also has a built-in signal generator and a repository of IQ recordings that can be used for experimentation and testing the various decoders.
The project releases are available on GitHub releases, and they cover Windows, Linux, and MacOS.
All the way back in 2014, we posted about Avare ADS-B Receiver, which back then was a simple RTL-SDR ADS-B receiver and map for Android devices. The author of this app, TFL, recently wrote in and shared that the app is now a modern, fully featured ADS-B app, having added many new features such as UAT decoding with aviation weather products and NEXRAD weather radar/lightning strikes shown on the map, aircraft pictures, better SDR support, traffic filters, and audio alerts.
ADSB Receiver lets you collect live air traffic data directly on your Android device using any RTL-SDR (RTL2832U) dongle and an OTG cable. No cloud. No fees. Just raw RF decoded in real time.
Dual-band reception — 1090 MHz Extended Squitter (ES) for worldwide traffic, and 978 MHz UAT for US general aviation traffic plus integrated weather products (METAR, TAF, PIREP, SIGMET, AIRMET, WINDS, NOTAM)
Live aircraft details — tap any target on the map to pull a live photo alongside aircraft type and registered operator
NEXRAD weather imagery — receive official NEXRAD radar images over UAT 978 MHz
Network send/receive —
Forward all received data to any GDL90-capable EFB app (AvareX, ForeFlight, iFlyGPS, DroidEFB, and others)
Stream dump1090/dump978 frames to any SDR tool on your network, or ingest from an external source
Bias Tee and Gain support — power an external LNA or active antenna, adjust Gain as needed
Proximity alerts — configurable range-based traffic warnings with optional callsign filtering; useful for drone pilots monitoring airspace
Thank you to an anonymous contributor (known only as wonderingStars on GitHub) for writing and sharing their project, 'FoxSDR'. FoxSDR is advertised as a 'software-defined radio receiver written from scratch'. Like most receiver programs, it includes a spectrum and waterfall and various demodulation modes.
Key defining features to note include that it is completely browser-based, includes a built-in ADS-B decoder and map, and natively supports drivers for the HackRF, Airspy, and RTL-SDR. Being browser-based means that the server can run remotely and be placed close to the antenna to reduce signal losses, and the SDR can be accessed from any networked device. They also show that they are working on adding AIS, APRS, SSTV, Morse, RTTY, POCSAG, Inmarsat-C, and more to the program in the future.
The contributor writes that FoxSDR is currently Windows-only; however, they will add full Linux support once the Windows version is completely stable. They note that they are in the final stages of the beta and that, based on telemetry, they have over 100 daily users. They note that their three-year development plan includes plans to support all operating systems, including Android.
You may have seen in the news that researchers have recently mapped the brain and nervous system of a fruit fly and digitally simulated it in what they call a 'connectome'. Without additional training, the connectome exhibited fruit fly-like behavior when connected to a virtual body, suggesting that the fruit fly's behavior is encoded in its brain structure.
The fly brain neural network can also be hacked into performing other tasks. Various researchers have already repurposed it for tasks like controlling robots, driving a simulated car, playing virtual games like Beat Saber and Doom, trading crypto, and more. One novel fly brain application related to RTL-SDRs was submitted to us by Nik K (SV1EEX). Nik used the fruit fly connectome to tune an RTL-SDR-based FM radio. Nik writes:
Can the reconstructed nervous system of a fruit fly navigate the FM broadcast band and find a radio station?
I built an open-source experiment to test that question using an RTL-SDR Blog V4 and the published adult male Drosophila melanogaster CNS connectome: 165,122 traced neurons connected by more than 10 million signed neural edges.
The RTL-SDR V4 scans the real 87.5–108 MHz broadcast band and creates a panoramic RF environment. Instead of giving the software a list of stations, I convert that measured spectrum into an egocentric visual scene and present it through the 892 retinotopic optic columns used by the connectome simulation. Activity produced by anatomically identified DNa02 descending neurons moves a virtual receiver left or right along the dial.
The experiment also gives the simulated biomimetic fly a substituted RF “mechanosensory” channel. Spectral shape is mapped to bilateral Johnston’s-organ input, while the 19 kHz stereo pilot and 57 kHz RDS subcarrier stimulate JO-A and JO-B populations. This helps distinguish stations that appear similar in power and occupied bandwidth. These mappings are engineered sensory substitutions; they are not a claim that biological flies can detect radio waves.
In one preliminary run on a panorama recorded with the RTL-SDR Blog V4, the connectome-driven controller started at 97.750 MHz. Without receiving the target frequency directly, it entered the predefined ±100 kHz acquisition region around the hidden 95.200 MHz target after 33 actions and stopped at 95.126973 MHz.
The result is deliberately reported as a single preliminary observation. The repository separates external acquisition from neural DNp09 lock events and includes random, visual-only and direct-peak controllers for controlled comparisons.
I describe the resulting system as a connectome-driven virtual embodied agent operating in an RF-derived sensory environment—effectively, a digital fruit-fly nervous system whose world is the FM spectrum and whose movement consists of tuning a radio.
The complete source code, Windows setup, RTL-SDR V4 compatibility fixes, connectome setup procedure, technical manual, experimental protocol, limitations and acquisition dashboard are available here:
Thank you to Reid Crowe for submitting his project, "voacap-skill." This skill for Claude Code AI (a frontier LLM) lets Claude access and use the latest VOACAP ionospheric propagation data in conversations.
Instead of manually filling out a form for each prediction and analyzing the results yourself, with the voacap-skill, users can ask Claude questions like, "What's the best band to reach Tokyo from Columbus, Ohio around 0300Z in October?" and Claude will run a VOACAP prediction in the background and return an answer. Reid explains:
If you've ever used VOACAP, VOACAP Online, or watched a contest DXpedition plan its band schedule, you already know the engine underneath this: it's the same NTIA/ITS point-to-point HF prediction model that's been the industry standard for propagation forecasting since the 1980s. It takes a transmitter location, a receiver location, a month, and a sunspot number, and tells you — for every hour of the day and every frequency you care about — how reliable that circuit is likely to be.
voacap-skill takes that engine (via voacapl, the modern Linux/GFortran port, on macOS/Linux, or the native NTIA/ITS Windows engine on Windows) and wires it into Claude Code as a "skill" — a capability Claude can reach for on its own.
The skill is free and open-source, with the code available on GitHub. Below, Reid provides some more examples of what you can ask Claude once it has access to VOACAP data.
Thank you to Patricio for writing in and sharing with us his release of HamRadioWeb, a browser-based remote receiver with a focus on FT8 and FT4 reception. If you're not aware, FT8 and FT4 are amateur radio digital fixed-format modes that can be decoded even with very weak signals.
The software works by running a small server bridge app alongside JTDX/WSJT-X on the shack PC. Users can then log in from anywhere in the world on any device via the browser-based system. Once logged in, you can transmit and monitor, just as if you were sitting in a ham shack.
HamRadioWeb is designed to streamline remote FT8/FT4 operating directly from any mobile browser or PC without requiring complex setups like VPNs or port forwarding. In addition to remote TX/RX control, it features:
Live FT8 geospatial heatmaps and signal footprint visualization.
Grid-level SNR benchmarking against nearby stations.
Azimuthal radar & path telemetry relative to the shack.
Automated DXCC and award hunting synchronized with logbook data.
It’s built to make remote digital mode operating visual, data-driven, and easily accessible on the go.
HamRadioWeb is free for unlimited decodes, but limited to 10 TX's per day. Premium is a paid service costing $4.99 per month, which provides unlimited access.
HamRadioWeb: A Demo of the FT8/FT4 Terminal Display
Back in May, we posted about the release of OpenWXSDR, an open-source Python framework that turns one or more RTL-SDR or Airspy SDRs into a fully automated radiosonde ground station running on a Raspberry Pi 4/5 or Linux x86 machine.
Recently, OpenWXSDR creator Mike (DL2MF) wrote in to share that V1.0.62 has been released, bringing improvements to decoder quality and stability. The update also improves the software's setup and configuration stages and adds a radiosonde statistics page.
Another development is that the sondehub.org aggregation site has verified the OpenWXSDR telemetry data and now allows the upload of DFM06, DFM09, DFM17, M10, M20, RS41, and RS92 radiosonde data to its network via OpenWXSDR.
Thank you to Marc Lictman, vice president of GNU Radio, for writing in and sharing with us his new project called "GNU Radio World," which is essentially GNU Radio Companion in a web browser, written in WebAssembly.
If you're not familiar with it, GNU Radio is a very popular free and open-source toolkit for implementing digital signal processing algorithms and applications. It lets you experiment with and build radio receivers, transmitters, and DSP chains through a graphical block-based flowgraph.
Marc Lictman writes:
I thought your readers might be interested in the relatively new website that I put together, https://gnuradioworld.com, as it is starting to have some nice RTL-SDR support, e.g. there is a basic spectrum analyzer and a full ADS-B application with map, but the best part is that it's really just GNU Radio in the browser so you can assemble your own flowgraphs and play around without installing anything, either with live USB SDRs, signal recordings, or simulated signals. It runs entirely client-side and comes with several out-of-free modules (OOTs), including gr-adsb by Matt Hostetter.
The other nice part about GNU Radio World is it comes with dozens of example flowgraphs (see tab on the left) as well as a bunch of example IQ recordings that can be used in place of the typical File Source block, and when you run the flowgraph it streams the IQ to your browser, a lot of the IQ recordings are used in the example flowgraphs to show off various OOTs functionality.
The whole project is free and open source (GPLv3), I think that it will be especially valuable for those learning RF signal processing, and those without a Linux background who want to jump straight into learning GNU Radio. Here are some specific example flowgraphs that may be of interest to RTL-SDR enthusiasts:
If anyone wants to reach out, they can email [email protected] or join the Discord server linked at the top of the site.
We test-drove GNU Radio World with both RTL-SDR Blog V3 and V4 dongles and found it to work well. However, it seems that V4L support has not been added yet. We have forwarded this feedback to Marc, so hopefully it will be supported soon.
GNU Radio World Browser Flow GraphGNU Radio World: Running an RTL-SDR Blog V3
