A real-time SDR spectrum, waterfall, and multi-decoder console for Windows and linux.

Work in progress. SignalScope is under active development (v0.0.2). Features, decoders, and APIs may change without notice, and things may break.

• Live spectrum + scrolling waterfall with adjustable FFT size and averaging
• Drop decoders directly on the spectrum (Ctrl+click) — each runs in its own down-converted channel across a worker-thread pool
• Band browsing (pan the view to retune the radio), band-plan overlays
• Audio output for broadcast/voice modes with volume, mute, and a level meter
• IQ recording with pre-buffer
• Dual-RTL mode (two independent receivers side by side)
• Dockable, persistent panel layout

Decoders are pluggable "channel" types placed on the spectrum:

Decoded text lands in the unified Pager panel; audio modes play through the shared audio output. The OOB EPG decoder has its own dedicated EPG tab with collapsible sections for channel lineup, service names, MAC control messages, host config, and raw system strings. The HD Radio decoder has a dedicated HD Radio tab showing station info, now-playing track, program selector, signal quality, and technical details. More decoder types are planned — see docs/ADDING_A_DECODER.md for the plugin interface.

• ADS-B (1090 MHz) and ERT/SCM utility meters — these are wideband, full-stream modes and will arrive as a separate decoder family.

The SCTE 55-2 (DAVIC Mode B) out-of-band decoder processes the cable forward data channel (772 ksym/s QPSK, 1.544 Mb/s). It implements the full protocol stack:

IQ → QPSK Demod → Diff Decode → Derandomize → SL-ESF Frame Sync
   → RS(55,53) FEC → ATM Cells → AAL5 → IP/UDP → DSM-CC Carousel
   → EPG Extraction

Extracted data types:

• Channel Lineup — callsign → virtual channel number (from DAVIC channel map, tag 0x0B)
• Service Names — friendly multi-word display names (e.g. "Paramount+ with SHOWTIME")
• MAC Control — provisioning/service channel frequencies, upstream rates, power levels (VCI 0x0021)
• Host Config — OCAP bootstrap: in-band QAM frequency/program, CVS/firmware URLs, -D flags (VCI 0x0FA2)
• System Strings — firmware identifiers, CableCARD certs, filenames, UI messages extracted from ATM payloads
• BIOP Objects — carousel file inventory (service gateway, configuration files, logo resources)

Note: Requires a cable TV provider that broadcasts SCTE 55-2 OOB forward data (tested on Spectrum/Charter). Place the decoder at the OOB frequency (typically 70–130 MHz). Use a sample rate ≥ 2 Msps for reliable decoding. The Airspy is recommended for best sensitivity.

Decodes HD Radio digital subcarriers on FM broadcast stations via libnrsc5. Place the decoder at the center frequency of any FM station (88–108 MHz) with digital HD Radio sidebands.

Features:

• Multi-program audio with program selector
• Station info: call sign, slogan, facility ID, transmitter location
• Now Playing track metadata (title, artist, album, genre) via ID3
• Signal quality: MER (modulation error ratio), BER (bit error rate)
• Codec details (HE-AAC mode, blend control, gain, latency)
• Program type per channel (Rock, News, Jazz, etc.)
• Local time with DST info from the station
• Emergency alerts

Build requirement: See COMPILE.md for libnrsc5 build instructions. The library must be built from source with FAAD2 (AAC audio codec) enabled. Requires a sample rate ≥ 6 Msps for reliable digital lock — the Airspy or HackRF is recommended.

SignalScope builds with the MSYS2 / MinGW-w64 toolchain using CMake + Ninja. See COMPILE.md for full instructions, including optional Airspy and LibreSDR (UHD) setup.

cmake -S . -B build -G Ninja
ninja -C build

• CableSniffer — OOB EPG protocol reverse-engineering (SCTE 55-2)
• multimon-ng — Elias Oenal, Thomas Sailer (FLEX)
• Dear ImGui / ImPlot — Omar Cornut, Evan Pezent
• miniaudio — David Reid
• zlib — Jean-loup Gailly, Mark Adler
• Created by Sarah Rose