DSP Visualisations
What it is
A running effort to make the digital signal processing behind SDR visible — IQ constellations, spectra, and the way real signals behave — through small tools and explanatory writing. It includes a simple IQ-visualisation plugin for SDRconnect for people who want a quick feel for IQ without the GNU Radio learning curve, alongside step-by-step setup notes.
Why I built it
I care as much about why things work as how, and IQ/DSP concepts click far faster when you can see them move. These pieces are aimed at demystifying the theory rather than just listing procedures.
Current status & goals
- Setup guide for IQ visualisation with an SDRplay (GNU Radio / Radioconda), plus a lightweight SDRconnect plugin as a quick-start path.
- Explorations of FM and repeater IQ.
- The material became a full talk, Making the invisible visible, given to CDARC in May 2026 and invited to the RSGB Convention in October 2026, and a RadCom article, Seeing signals: I and Q from first principles (September 2026).
- A purpose-built Raspberry Pi device plots live IQ and demodulates the same signal to audio for demonstrations.
Key links
My code
- sdrconnect-iq-visualiser — the SDRconnect IQ visualisation plugin
- sdrplay-gnuradio-examples — GNU Radio flow graphs for SDRplay devices
Elsewhere on this site
- Setup for IQ visualisation and digital signal processing
- Talks & Publications — the IQ talk and article
- Raspberry Pi SDR — the demonstration device
Tools used
- SDRplay — the RSP receivers
- GNU Radio — the DSP environment
- Radioconda — the easy path to a working GNU Radio install
