Shows the current VIS detection state machine position (Idle, Leader,
Break, Start bit, Data bits, etc.) in the signal monitor. This helps
diagnose why decoding may not be starting - e.g. if the VIS detector
is stuck in Idle despite a leader tone being present, the signal may
not contain a valid VIS header.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The Doppler tracking thread emits detecting events every 5s from a
separate thread, unaware of decode state. The previous to_dict() change
included signal_level for ALL detecting events, causing the frontend to
replace the decode progress canvas with the signal monitor mid-decode.
Fix: use None as default for signal_level so only signal-metrics events
(which explicitly set the value) include the field. Also add a frontend
guard to ignore detecting events while the UI is in decoding state.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Shows RMS audio level bar and SSTV tone classification (leader/sync/noise)
via SSE during detecting mode, replacing the static "Listening..." state
with actionable signal feedback.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
slowrx is a GTK GUI app that doesn't support CLI usage, so the SSTV
decoder was silently failing. This replaces it with a pure Python
implementation using numpy and Pillow that supports Robot36/72,
Martin1/2, Scottie1/2, and PD120/180 modes via VIS header auto-detection.
Key implementation details:
- Generalized Goertzel (DTFT) for exact-frequency tone detection
- Vectorized batch Goertzel for real-time pixel decoding performance
- Overlapping analysis windows for short-window frequency estimation
- VIS header detection state machine with parity validation
- Per-line sync re-synchronization for drift tolerance
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Adds a general-purpose SSTV decoder alongside the existing ISS SSTV mode,
supporting USB/LSB/FM modulation on common amateur radio HF/VHF/UHF
frequencies (14.230 MHz USB, 3.845 MHz LSB, etc.) with auto-detection
of modulation from preset frequency table.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
