Software Defined Radio

inspectrum

inspectrum is where you go after the capture. It loads a recorded IQ file — the kind rtl_sdr, hackrf, or a receiver produced — and gives you a detailed, zoomable spectrogram of it. You can measure a signal’s timing and bandwidth, drop cursors to read off symbol rates, and use its overlays to pull the raw bits out of a simple digital transmission by eye. For reverse-engineering an unknown signal, it’s the microscope: capture the burst live, then dissect it here at leisure.

inspectrum is a graphical application, so Oniomarchy launches it into its own window from Security → Software Defined Radio → inspectrum. Official-repo package.

Using it

1. Record a capture with one of the hardware tools (e.g. rtl_sdr -f 433.92M -s 2048000 capture.iq).
2. Open the file in inspectrum and set the sample rate you captured at.
3. Zoom into the burst on the spectrogram and adjust the power/contrast so the signal stands out.
4. Measure it — use the amplitude and frequency plots to read symbol timing, and place a cursor grid to line up the symbols.
5. Extract symbols directly from the display for simple OOK/FSK signals, then take those bits into urh for full protocol reconstruction.

inspectrum analyzes; it doesn’t talk to hardware itself. Capture live, analyze here.