BufferedReader.read(n) on non-interactive streams (Python 3.14) blocks
until the full n bytes accumulate, starving the decoder of real-time
PCM data. Use os.read() on the raw file descriptor instead, which
returns as soon as any data is available. Falls back to .read() for
file-like objects without fileno() (e.g. BytesIO in tests).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Replace select.select()+os.read() with a blocking reader thread feeding
a queue, matching pager's working pattern. The select() approach fails
to detect available data on Python 3.14's BufferedReader-wrapped pipes.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
rtl_fm prints device info, tuning, and errors to stderr but the morse
route only logged these server-side. Now stderr lines are forwarded to
the morse queue as info events, displayed in a compact diagnostic log
below the scope canvas. After 10s with no audio data, the scope text
escalates to prompt the user to check the SDR log.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Replace blocking rtl_stdout.read() with select()+os.read() so the
decoder thread emits diagnostic heartbeat scope events when rtl_fm
produces no PCM data (common in direct sampling mode). Add waiting-state
rendering in the scope canvas and hide the generic placeholder/status
bar for morse mode.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add automatic gain control (AGC) before Goertzel processing to normalize
quiet audio from direct sampling mode where the -g gain flag has no effect.
Fix broken adaptive threshold bootstrap by adding a 50-block warm-up phase
that collects magnitude statistics before seeding noise floor and signal peak.
Lower threshold ratio from 50% to 30% for better weak-CW sensitivity.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Enable direct sampling (-D 2) for RTL-SDR at HF frequencies below 24 MHz
so rtl_fm can actually receive CW signals. Add startup health check to
detect immediate rtl_fm failures. Push stopped status event from decoder
thread on EOF so the frontend auto-resets. Add frequency placeholder and
help text. Fix stop button silently swallowing errors.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
New signal mode for decoding Morse code (CW) transmissions via SDR.
Includes route blueprint, utility decoder, frontend UI, and tests.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
