SDR–; open source SDR with a patchable signal graph, Rust DSP, web UI

sdr--

sdr-- is 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 Rust server handles the radio and signal processing. The React interface runs in a desktop window or browser. You can run both on one computer, or leave the server beside the antenna and connect over the network. A built-in signal generator lets you try it without an SDR.

Status

sdr-- is under active development. Most decoders have been tested with generated IQ fixtures; only some have been verified on air. The channel catalog lists the evidence for each mode and its limitations. Experimental modes may provide acquisition or measurements without decoded audio or video.

What you can do

• Listen to AM, NFM, broadcast FM with stereo and RDS, SSB, and supported digital voice modes.
• Decode aircraft, ship, amateur, pager, sensor, and other radio traffic. See the full channel list.
• View spectrum, waterfalls, decoded messages, position maps, and received images.
• Scan frequencies and save workspaces, presets, and bookmarks.
• Record device IQ, channel baseband, or audio; replay IQ through the same decoders.
• Use coherent receivers for direction finding, antenna combining, beamforming, and passive radar.
• Export IQ over UDP or TCP and forward decoded events to webhooks, Matrix, or MQTT.
• Control the running receiver through REST, WebSocket, or MCP.

Install

Download a desktop installer or portable server from GitHub Releases. Installation instructions cover each package, Homebrew, Nix, and containers.

On macOS, install the desktop app with Homebrew:

brew tap newspicel/tap
brew install --cask sdrminusminus

For the headless server, use brew install sdrmm.

To run the server with Docker Compose on Linux:

git clone https://github.com/Newspicel/sdrminusminus.git
cd sdrminusminus
docker compose up -d

Open http://localhost:8080. The server has no authentication by default; see configuration and security when setting up network access.

Try a receiver

1. On the starter Device node, choose Signal Generator (virtual). The connected Scope shows the generated signals.
2. Choose + Node and add an NFM channel.
3. Connect Device IQ to NFM IQ, then NFM audio to Speaker audio.
4. Set the channel to 300 kHz above the radio's centre and start audio on the Speaker. You should hear a 1 kHz tone.

Your first receiver walks through the controls and switching to hardware.

Standard builds include native RTL-SDR, HackRF, SDRplay, and CR-8 drivers. SDRplay and CR-8 also require their vendor libraries. Desktop installers and containers bundle SoapySDR modules for Airspy/AirspyHF, bladeRF, LimeSDR, PlutoSDR, and SoapyRemote. See the hardware guide for requirements.

Screenshots

These captures use the built-in signal generator or repository IQ fixtures. Regenerate them with cargo xtask screenshots.

Spectrum and waterfall	Rack view

FT8 decoding	Signal identification

Aircraft positions	Ship positions

Slow-scan television	Amateur television

Pager messages	Broadcast FM

Build from source

You need the repository's pinned Rust toolchain, a C/C++ compiler, CMake, Node 26, pnpm 11, and SoapySDR 0.8 development files. The build guide lists platform prerequisites.

git clone https://github.com/Newspicel/sdrminusminus.git
cd sdrminusminus
pnpm --dir web install --frozen-lockfile
pnpm --dir web build
cargo run -p sdrmm

Open http://localhost:8080. For development, cargo xtask dev starts the server and a frontend with hot reload at http://localhost:5173. Add --watch to restart the backend when its files change.

To build with only virtual sources and network receivers:

cargo run -p sdrmm --no-default-features --features net-client

Development

See Contributing and the development guide for testing, generated files, and releases.

Documentation and API

• User and developer guide
• Swagger UI: /api/docs on a running server
• OpenAPI: /api/openapi.json or the checked-in openapi.json

License

Copyright (C) 2026 sdr-- contributors.

sdr-- is licensed under the GNU General Public License, version 3 or later. THIRD_PARTY_NOTICES.md lists distributed dependencies and bundled hardware components. Their license texts are also available in the app's About panel.