Cascade-SDR: A Web-Based Multimode Receiver for RTL-SDR

Cascade-SDR: An RTL-SDR Receiver in Your Browser

Developer Jens Engfors has released Cascade-SDR on GitHub — a free, open-source, web-based receiver app built specifically for RTL-SDR (RTL2832U) dongles.

Cascade-SDR app screenshot

Architecture: Python Backend + Browser Frontend

Cascade-SDR splits the work between two ends:

• Backend (Python): Owns the dongle and handles all DSP processing.
• Frontend (browser): Renders the UI, waterfall, audio playback, and maps.
• Transport: The two communicate over a WebSocket.

The practical upside is that you can run the backend on a Raspberry Pi or a mini PC and reach it from any phone, tablet, or laptop browser on your local network — turning one small box into a multi-client listening station.

Cascade-SDR main interface

Analog Reception: From Broadcast to CW

Cascade-SDR offers a live spectrum + waterfall view and click-to-listen demodulation for:

• Modes: WFM, NFM, AM, SSB, and CW
• Extras: RDS decoding, FM stereo, and a built-in Morse decoder

On top of that, it includes a wideband sweep mode, a channel scanner, IQ recording and replay, and a handy antenna helper that tells you how to set up the rtl-sdr.com dipole kit for the frequency you have tuned to.

Digital Modes

Beyond analog, Cascade-SDR can decode a wide range of digital signals when paired with the right external tools:

• Aviation / maritime: ADS-B (aircraft), AIS (ships)
• Amateur / data: APRS, ACARS
• Broadcast: DAB+
• Weather satellites: NOAA APT imagery
• Imaging / telemetry: SSTV, POCSAG/FLEX pagers
• ISM devices: 315–915 MHz weather stations and TPMS sensors

Note that most of these digital modes require installing supporting decoder software, such as dump1090 (ADS-B), ais-catcher (AIS), direwolf (APRS), welle-clide (DAB+), multimon-ng (POCSAG), and rtl_433 (ISM devices).

Platforms & License

• Runs on Windows, macOS, and Linux / Raspberry Pi.
• The README includes installation instructions for each platform.
• Free and open source. The author discloses that the project used Claude during development (an AI-disclaimer is included in the announcement).

For hobbyists who want a "just open a browser" SDR listening post at home, Cascade-SDR offers a fairly complete one-stop solution.

Links

• GitHub: https://github.com/rzfk2v/Cascade-SDR
• News write-up: https://www.rtl-sdr.com/cascade-sdr-a-web-based-multimode-receiver-app-for-rtl-sdr-dongles/