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

SDR--

A software-defined radio application for listening, decoding, and recording. Connect radios, channels, and displays in Patch view, then pin your everyday controls to Rack view.

Run the desktop app with a local SDR, or place the server near your antenna and connect through a browser. Both use the same receiver engine and interface.

Install

Download a desktop installer or portable server from GitHub Releases. The installation guide covers macOS, Windows, Linux, Homebrew, Nix, and Docker.

On macOS:

brew tap newspicel/tap
brew install --cask sdrminusminus

For a headless server on macOS or Linux, install sdrmm from the same tap:

brew install sdrmm
brew services start sdrmm

Open http://localhost:8080. For remote access, configure authentication and HTTPS.

Start with an RTL-SDR

Attach an antenna and plug the RTL-SDR into the computer running SDR--.
Select it on the Device node. Set the sample rate to 2.4 MS/s and tune to a local FM station.
Add a WFM channel from + Node and set it to the station's frequency.
Connect Device IQ to WFM IQ, then WFM audio to Speaker audio.
Start playback on the Speaker. Select a node and press p to pin it to the Rack.

Your first receiver walks through tuning, gain, audio, and RDS. See the hardware guide for other receivers and package-specific driver requirements.

What it supports

Listening: AM, NFM, broadcast FM with stereo and RDS, SSB, and digital voice.
Decoding: aircraft, ships, amateur radio, pagers, sensors, images, and more.
Displays: spectrum, waterfalls, maps, decoded messages, and video.
Recording: device IQ, channel baseband, and audio, with SigMF playback.
Radio tools: scanning, signal identification, coherent arrays, direction finding, and passive radar.
Automation: REST, WebSocket, MCP, network IQ export, and event forwarding.

SDR-- is under active development. The channel catalog lists each mode's test coverage and limitations, including partial experimental decoders.

Screenshots

These captures use debug-build signal sources and 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 and contribute

Use the repository's pinned Rust toolchain, a C/C++ compiler, Clang/libclang, CMake, Python 3.12+, GNU Make, Node 26, and pnpm 11.

git clone https://github.com/Newspicel/sdrminusminus.git
cd sdrminusminus
python3 scripts/build-media.py
export FFMPEG_DIR="$(python3 scripts/build-media.py --print-prefix)"
pnpm --dir web install --frozen-lockfile
pnpm --dir web build
cargo run -p sdrmm

Open http://localhost:8080. For frontend hot reload and backend watching, run cargo xtask dev --watch and open http://localhost:5173.

The signal generator and synthetic test radios are available in debug builds. Release builds support real receivers and recording playback.

Command	Purpose
`cargo xtask check`	Format, lint, type-check, build, and check generated files
`cargo xtask test`	Rust and frontend tests without hardware
`cargo xtask smoke`	Browser tests against the server
`cargo xtask codegen`	Generate OpenAPI and TypeScript types
`cargo xtask audit`	Dependency checks

Read Contributing, the build guide, and architecture for prerequisites, crate boundaries, and tests.

Documentation and API

User and developer guide
Swagger UI: /api/docs on a running server
OpenAPI: /api/openapi.json or openapi.json

License

Licensed under the GNU General Public License, version 3 or later. Third-party notices and license texts are also available in the app's About panel.