### 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