I've set off time to blog about getting my broadband RF scanner (connecting to USRP B200 via WebUSB) to work in WASM.

https://rf-survey.habets.se/

It's basically https://blog.habets.se/2026/08/Broadband-RF-scanner-revisite..., but in the browser.

I also have an AX.25 decoder (https://thomashabets.github.io/ruwasm/) and plain old FM receiver (https://cement.retrofitta.se/tmp/rtlsdr-fm/) already. The latter two work with RTL-SDR, also via WebUSB, so no software installs or setup required.

I've been meaning to make a "GNU Radio in the Browser" (well, gnuradio-companion-like) for my RustRadio project to build flowgraphs without coding, but not gotten to it yet.

The "Help"->"Help" menu item is notably unhelpful:

> For questions, comments, or suggestions, you can email support@gnuradioworld.com, join the Discord server, or post a GitHub issue.

"Help"->"About" at least starts to clarify some things:

> GNU Radio, entirely in your browser — explore the open-source SDR ecosystem with zero install!

> GNU Radio World is a browser-based GNU Radio Companion flowgraph editor and WebAssembly runtime. You can place, connect, and configure blocks, then run the resulting flowgraph directly in your browser.

> It is designed to download only the WebAssembly modules corresponding to the blocks you use. This on-demand architecture keeps the initial download small and can support a limitless collection of out-of-tree modules (OOTs) in the future.

> GNU Radio World also includes a collection of real RF recordings that are downloaded only when you use them. You can inspect the recordings in the built-in recording view, adapted from IQEngine, and use them in the included flowgraph examples, allowing OOTs to be shown off with real recordings of the corresponding signals

I had no background in dsp or signal processing and found it so opaque as to be unusuable, even though I saw more skilled folks do amazing things with it.

*scratches head*

Might give it another go.

-Marc

First it takes the audio from your microphone. It then feeds it through a Hilbert transform to convert incoming audio into an IQ (complex) format. The advantage of an IQ signal format is that when you multiply it by another signal, the frequencies add or subtract, without getting extra image frequencies. This is why it's worth doing twice the computation in DSP work.

Then your audio is multiplied by a cosine wave with a frequency determined by a GUI slider, from -2000 to 2000 Hz.

This has the net effect of raising or lowering the pitch of your voice, like tuning in a single sideband transmission on ham radio.

To get the results out to the speakers, it samples only the real component to send to the audio output.

The net effect is it can raise or lower the frequency of your voice.

[1] https://gnuradioworld.com/#fg=H4sIAAAAAAAACsVXS2_bOBC--1fMTR...

https://www.gnuradio.org/news/2025-01-29-gnuradio-textbook/

If you have a certain DSP goal in mind (say, RF comms), and you want to do stuff but not absolutely balls-to-the-walls processing (at that point, presumably you'd move to hardware), you can design your stack in fairly modular and composable ways. The field is pretty mature and the techniques just work.

In a software context, you can decompose the abstractions fairly cleanly. You won't get 5G high performance networking but you can get good enough results.

[0] https://www.pysdr.org/