733fe76ed5
Increase fft_size from 512 (default) to 2048 for better NFM channel isolation, and add squelch_snr_threshold = 15.0 dB per channel to reject noise-triggered recordings. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
1.2 KiB
1.2 KiB
Why
The recorder generates many short false-positive recordings (360 bytes to ~4KB) triggered by noise, static, or weak signals. Multiple channels often fire simultaneously, suggesting wideband interference or poor channel isolation. The current config uses the default FFT size (512) and default squelch SNR threshold (9.54 dB), both of which are too permissive for noisy CB monitoring at 27 MHz.
What Changes
- Increase
fft_sizeto improve channel selectivity and reduce adjacent-channel false triggers - Add
squelch_snr_thresholdper channel to raise the signal-to-noise requirement for squelch opening - Uncomment and update the
fft_sizesetting (currently commented out at 1024, defaulting to 512)
Capabilities
New Capabilities
false-positive-reduction: RTLSDR-Airband configuration tuning to minimize noise-triggered recordings via FFT size and squelch SNR threshold adjustments
Modified Capabilities
(none)
Impact
- Configuration: Changes to
rtl_airband.confonly — no new services or code - Pi resources: Higher
fft_sizeincreases CPU usage slightly; monitor after deployment - Recording behavior: Fewer but higher-confidence recordings; very weak legitimate signals may be missed