Recording and playback
| Node | Records | Wire from | Format |
|---|---|---|---|
| Recorder | The Device's full IQ | Device iq | SigMF |
| Baseband recorder | One channel's filtered IQ | Channel baseband | SigMF |
| Audio recorder | One channel's audio | Channel audio | 48 kHz 16-bit WAV |
| Time machine | IQ from before you pressed the button | Device iq | SigMF |
A SigMF recording is two files: samples in .sigmf-data, frequency, rate, and time in
.sigmf-meta. Keep them together.
Record on a recorder is a switch saved with the workspace. While it is on, the server records whatever is wired in: it follows rewiring, keeps going with the browser closed, and starts again after a restart.
Decoded messages are not recordings. For those, wire events to a Decoder log.
Record IQ
Wire Device iq to a Recorder, press Record, then Stop. On a multi-lane radio the
wired port picks the lane. Wire GPS position to store the location.
A clean server shutdown finishes open recordings. Killing the process can leave one incomplete.
Record a channel
Baseband recorder keeps a channel's IQ after filtering and before squelch. The files are much smaller than full Device IQ and can be played back like any other recording. Changing the mode or the Device rate, or removing the channel, ends the file.
Audio recorder keeps what reaches it, after squelch and any Audio FX it is wired behind. Closed squelch writes silence so timing stays intact. Mode and rate changes do not stop it. The file stays playable even if the server stops mid-recording.
Both recorders take several channels and write one file per wired input.
Time machine
Capture a signal after it happened:
- Wire Device
iqto Time machine, and GPSpositionif you have one. - Set how many seconds to keep and press Arm.
- Press Capture to save the buffer and keep recording live.
- Stop ends the file and stays armed. Disarm frees the memory.
The buffer uses seconds × sample rate × 8 bytes, up to 1 GiB. The node shows both. The sample
rate is locked while armed. Retuning starts a new segment in the same recording.
Play a recording
In Library → Recordings, press Open as source. A Recording node appears. Wire it to channels and displays like a Device, then use play, pause, and seek to decode the same samples again with different settings.
Upload SigMF adds a recording from your computer, as a .sigmf archive or a
.sigmf-meta and .sigmf-data pair.
Tags and notes
In Library → Recordings, choose Annotate to add comma-separated tags and a note. Search covers names, tags, and notes. Annotations live in the SigMF metadata, so they travel with the files.
Download
Download IQ as the original SigMF archive or as a stereo float WAV with I and Q as channels. WAV keeps the samples but not all metadata. A failed download aborts instead of handing you a truncated file.
Where files go
Recordings go to sdrmm/recordings in the platform data folder, with audio in audio/. Change it
with --recordings-dir. Containers use /data/recordings. The library rebuilds itself from the
SigMF files on disk.