- Replace _running bool with threading.Event for correct cross-thread visibility
- Add _proc_lock to guard _rtl_proc/_hackrf_proc across worker/main threads
- Use register_process + safe_terminate (pipe close + SIGKILL fallback on timeout)
- Compute HackRF frequency as band midpoint (hz_low+hz_high)//2, not hz_low
- Guard start() for idempotency — double-call no longer leaks threads
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Implements RFDetector class that wraps rtl_433 (433/868MHz) and hackrf_sweep
(2.4/5.8GHz) subprocesses, emitting RFObservation objects onto a shared queue.
Includes signature matching, frequency band validation, and power thresholding.
- _handle_rtl433_line(): Parse JSON output, filter drone bands, emit observations
- _handle_hackrf_line(): Parse CSV output, average power levels, threshold at -90dBm
- start()/stop(): Manage subprocess threads for concurrent RF detection
- Graceful handling of missing tools (rtl_433, hackrf_sweep)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>