Transmission Sources
The transmission source determines what audio or signal the transmitter sends. It is selected in the Transmission Source section of the Transmitter Interface.
Choose the simplest source for the task[edit | edit source]
- Play a recording: select Audio File, press Choose..., and pick a WAV or MP3. Leave Repeat off for a one-time transmission.
- Speak live: select Microphone, choose the input device, and check the monitor with a short transmission.
- Relay a stream: select Audio File and press URL.... Supply a direct supported HTTP or HTTPS audio stream, not a page containing an audio player.
- Send desktop audio on Linux: choose an available PipeWire source. Stereo selects WFM automatically.
- Use a signal from another program: see GNU Radio IQ below. This needs matching sample-rate and connection settings.
Start with Audio Gain 0.9 and listen to the result. If it distorts, lower the gain before increasing transmitter power. Tone (Hz) is not an extra source selector; a greyed-out field is not needed by the current source.
Source types[edit | edit source]
| Source | Description |
|---|---|
| Audio File | Plays a local file or an HTTP or HTTPS audio stream. Supported local formats are wav, mp3, aiff, aif, and au. Files may be selected with Choose... or dragged onto the window. URL... selects a stream, and Repeat restarts a local file when it ends. |
| Microphone | Transmits live audio from a selected input device. The device list appears when this source is chosen. Availability depends on the operating system audio setup. |
| White Noise | Generates broadband noise. Useful for testing receivers and observing the occupied bandwidth. |
| PipeWire | Streams the system audio (mono) on Linux systems with PipeWire. Only shown when PipeWire is available. |
| PipeWire Stereo | Streams system audio in stereo, intended for WFM broadcasting. Selecting it forces the WFM mode. Only shown when PipeWire is available. |
| GNU Radio IQ | Receives complex IQ samples from GNU Radio over a local TCP connection. The Tone field becomes IQ Port (suggested port 7355). Point a GNU Radio TCP sink at 127.0.0.1 on that port. The source sample rate equals the requested bandwidth. Selecting it forces the IQ mode. |
Lua modulation inputs[edit | edit source]
An installed Lua modulation may use the ordinary audio sources, require no audio source, or add pickers for images, videos, and data files. A source-free mode disables the Source Type field and controls its own output timing. Required extension inputs must be selected before transmission can start.
Audio gain[edit | edit source]
The Audio Gain field (default 0.9) scales the source level before modulation. Driving it high increases loudness but pushes the transmitter into compression and distortion, especially with presets that have little headroom, see Radio Presets.