sdr-recorder/openspec/specs/false-positive-reduction/spec.md at 5f3c41ca3dec8108ffba44d282ebf5980669f1c8 - sdr-recorder - Gitea: Git with a cup of tea

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Michael Smith 733fe76ed5 Tune FFT size and squelch to reduce false-positive recordings

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>

2026-03-19 13:25:37 +00:00

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Requirement: FFT size configured for NFM channel isolation

The system SHALL use an fft_size of 2048 or greater to provide sufficient spectral resolution for separating NFM channels spaced 10 kHz apart.

Scenario: FFT size set in config

WHEN the RTLSDR-Airband configuration is loaded
THEN the fft_size is set to 2048

Requirement: Squelch SNR threshold configured per channel

Each monitored channel SHALL have a squelch_snr_threshold set to reduce false triggers from noise and weak signals.

Scenario: Squelch threshold applied

WHEN a signal is detected on a monitored channel
THEN the squelch only opens if the signal exceeds the configured SNR threshold (starting value: 15.0 dB)

Scenario: Noise below threshold is rejected

WHEN noise or interference is present but below the SNR threshold
THEN no recording is triggered