Tolerate intermittent ambiguous windows during leader detection (up to
3 consecutive misses), use energy-based break detection when tone
classification fails at leader-break boundary, and add single-bit VIS
error correction for parity-bit and data-bit corruption on noisy HF.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The previous fix (f29ae3d) introduced a regression: when VIS parity
check failed or the VIS code was unrecognized, the detector entered
DETECTED state permanently and never resumed scanning. Now it resets
to IDLE on validation failure and only enters DETECTED on success.
Also resets partial image progress counter between consecutive decodes
and adds SDR device claiming to general SSTV route to prevent conflicts.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
VISDetector._process_window() was calling self.reset() inside the
STOP_BIT handler, wiping self._buffer before feed() could advance
past the triggering window. All audio samples buffered after the
VIS STOP_BIT (the start of the first scan line) were silently
discarded, causing the image decoder to begin decoding mid-stream
with no alignment reference. The result was every scan line being
desynchronised from the first, producing the diagonal stripes and
scrambled colours seen in decoded images.
Fix: remove the premature reset() from _process_window(). The
STOP_BIT handler now sets state=DETECTED and returns the result.
A new remaining_buffer property exposes the post-VIS samples.
_decode_audio_stream() and decode_file() capture those samples
before calling reset(), then immediately feed them into the newly
created SSTVImageDecoder so decoding begins from sample 0 of
the first sync pulse.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add .gitignore entry for data/subghz/captures/ to prevent large
IQ recording files from being committed.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Three bugs preventing the live SSTV pipeline from working:
1. Race condition: self._running was set AFTER starting the decode
thread, so the thread checked the flag, found it False, and exited
immediately without ever processing audio.
2. Ghost running state: when the decode thread exited (e.g. rtl_fm
died), self._running stayed True. The decoder reported as running
but was dead, and subsequent start() calls returned without doing
anything - permanently stuck until app restart.
3. VIS detection fragility: unclassifiable windows at tone transition
boundaries (mixed energy from two tones) caused the state machine
to reset from LEADER/BREAK states back to IDLE, dropping valid
VIS headers on real signals.
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>
