https://github.com/vsergeev/radfly
An SDR-based listening server for AM medium wave and shortwave radio stations built with Zig
https://github.com/vsergeev/radfly
radio sdr zig zigradio
Last synced: 3 months ago
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An SDR-based listening server for AM medium wave and shortwave radio stations built with Zig
- Host: GitHub
- URL: https://github.com/vsergeev/radfly
- Owner: vsergeev
- License: other
- Created: 2025-05-06T04:36:47.000Z (about 1 year ago)
- Default Branch: master
- Last Pushed: 2026-01-09T08:39:58.000Z (5 months ago)
- Last Synced: 2026-03-27T23:42:00.808Z (3 months ago)
- Topics: radio, sdr, zig, zigradio
- Language: Zig
- Homepage:
- Size: 197 KB
- Stars: 5
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# radfly
radfly is a self-hosted, SDR-based listening server for AM medium wave and
short-wave radio stations with a simple web frontend. radfly is built on [ZigRadio](https://zigradio.org/)
and [http.zig](https://github.com/karlseguin/http.zig), and currently supports rtl-sdr and AirSpy HF+ SDRs.
The web frontend streams audio, supports scanning, bookmarks, and configuring
options like audio bandwidth and AGC mode. radfly can be run on Raspberry Pi 4
and similar single-board computers.
## Building
radfly requires Zig version 0.15.
```
$ git clone https://github.com/vsergeev/radfly.git
$ cd radfly
$ zig build -Doptimize=ReleaseFast
```
Install optional (but recommended) acceleration libraries:
* `sudo apt install -y libvolk-dev libliquid-dev libfftw3-dev` on Debian-based systems
* `sudo pacman -S libvolk liquid-dsp fftw` on Arch Linux-based systems
## Running
Start radfly with an SDR source, e.g. `mock` (for testing), `rtlsdr`, or `airspyhf`:
```
$ ./zig-out/bin/radfly --source airspyhf
```
radfly will be accessible at `http://localhost:8000`.
#### Local Network
Due to the dependency on [AudioWorklet](https://developer.mozilla.org/en-US/docs/Web/API/AudioWorklet) for streaming audio in the browser, the
radfly frontend must be served over a secure context (HTTPS) to be accessed
by other machines on a local network. [Caddy](https://caddyserver.com/) can be used as a secure reverse
proxy for this.
Start `caddy` (replace `radio-pi4` with your machine's hostname):
```
$ sudo caddy reverse-proxy --from radio-pi4.local --to :8000
```
radfly will now be accessible on the local network at `https://radio-pi4.local`.
#### Certificate Warning
`caddy` uses self-signed certificates for `*.local` hostnames, which can't be
trusted automatically by browsers and results in an insecure connection
warning. To remove this warning, import caddy's generated root certificate,
located at `/root/.local/share/caddy/pki/authorities/local/root.crt`, into your
browser's certificate manager.
## Usage
```
Usage: radfly [options]
Radio Configuration
--source SDR Source (default mock)
--device-index Device index (default 0)
--device-serial Device serial (default none)
--bias-tee Bias tee (default false)
--tune-offset Tune offset (default 50 KHz)
--initial-frequency Initial frequency (default 5000 KHz)
Server Configuration
--http-port HTTP listening port (default 8000)
--http-address
HTTP listening address (default 127.0.0.1)
Miscellaneous
--help Display usage
--version Display version
--debug Enable debug mode
```
## Design
The [ZigRadio](https://zigradio.org/) flowgraph consists of audio demodulation and power measurement
signal chains that feed into their respective `ApplicationSink`. Audio and
power samples are consumed by an application thread and pushed to active
clients via WebSockets. An RPC protocol over WebSockets allows clients to scan,
tune, and change various parameters in the flowgraph.
```mermaid
flowchart LR
A[Source] --> B[TunerBlock]
B --> G[LowpassFilterBlock]
subgraph s2 [Power Measurements]
G --> H[PowerMeterBlock]
H --> I[ApplicationSink]
end
B --> C[AGCBlock]
subgraph s1 [Audio]
C --> D[AMEnvelopeDemodulator]
D --> E[DownsamplerBlock]
E --> F[ApplicationSink]
end
```
## Tests
Run unit tests with:
```
$ zig build test
```
## License
radfly is MIT licensed. See the included [LICENSE](LICENSE) file.