Also known as: SDRangel
SDRangel is a free, open-source, cross-platform software-defined radio application that supports a broad range of devices and can run many receive and transmit channels simultaneously.1 Where a typical hobby receiver tunes one signal at a time, SDRangel treats a wideband capture as a workspace on which multiple channel plugins — each a demodulator or modulator — operate in parallel, making it a Swiss-army toolkit rather than a single-purpose receiver.
How it works
SDRangel is organized around device plugins and channel plugins. A device plugin opens a front end — RTL-SDR, Airspy, HackRF, LimeSDR, PlutoSDR, USRP, and more — and produces (or consumes, for transmit-capable radios) a stream of IQ samples spanning the device bandwidth. That wideband stream is fed to any number of channel plugins, each of which digitally tunes to an offset within the band, filters and decimates its slice, and runs a demodulator or modulator.
Channel plugins cover a wide catalog: broadcast and narrowband FM, AM, SSB, several digital-voice modes (D-STAR, DMR, System Fusion/YSF, and P25 via an integrated DSD-style decoder), analog TV, packet, and utility modes, plus a matching set of transmit modulators on TX-capable hardware. A server variant runs headless and is controlled over a REST API, and the whole thing can be scripted for automated monitoring. This parallel, plugin-per-channel architecture is what distinguishes SDRangel from single-VFO receivers.
Relevance to SDR
SDRangel appeals to users who want one program to do a lot: monitor several channels of a band at once, experiment with transmit as well as receive, or decode digital-voice modes without stitching together separate tools. Its built-in digital-voice channels overlap functionally with standalone decoders — it can, for instance, follow some P25 and DMR traffic directly — which makes it a capable all-in-one for casual monitoring across many protocols.
GopherTrunk is a separate project and shares no code with SDRangel; the two are functionally adjacent in that both can turn digital-voice IQ into audio. The differences are in scope and shape: GopherTrunk is a headless, pure-Go scanner focused specifically on trunked-radio control-channel following and channel-grant tracking across systems (P25, DMR, NXDN, TETRA, and others), shipping as a single static binary; SDRangel is a broad Qt GUI toolkit whose digital modes are a subset of its features and whose trunk-following is not its central purpose. They can share the same front-end hardware, and an operator might use SDRangel’s multi-channel view to survey a band before dedicating GopherTrunk to a specific trunked system.