Feature

Implement client-side noise floor auto-adjust for the FFT display. When enabled, automatically adjusts min_dbm so the noise floor sits at a user-configurable position (0-100%) in the FFT display.

Background

• The radio reports noise_floor_position and noise_floor_position_enable in display pan status
• These fields are read-only — display pan set noise_floor_position=N returns 5000002D (incorrect parameter)
• SmartSDR must implement this client-side by measuring the noise floor from FFT data and adjusting min_dbm/max_dbm

Current State

• UI controls (Floor slider + On/Off button) were built and removed — the auto-adjust algorithm needs tuning
• Initial implementation measured 20th percentile of smoothed FFT bins and adjusted min_dbm every 10 frames
• Problems observed: oscillation, jitter, and incorrect floor tracking

Proposed Approach

1. Use a slower update rate (every 50-100 frames instead of 10)
2. Heavier smoothing on the noise floor estimate (exponential moving average)
3. Hysteresis — only adjust if the error exceeds a threshold (e.g., 3 dB)
4. Damped adjustment — move min_dbm gradually toward the target, not in one step

Code Reference

• src/gui/SpectrumWidget.h — m_noiseFloorEnable, m_noiseFloorPosition members (still present)
• src/gui/SpectrumWidget.cpp — auto-adjust block in updateSpectrum() (still present, just unwired)
• src/gui/SpectrumOverlayMenu.cpp — UI controls removed, signals still in header
• src/models/RadioModel.cpp — setPanNoiseFloorPosition/Enable (can be removed, radio doesn't accept)

Related

• Relative Noise Floor Scaling #21 (Relative Noise Floor Scaling)

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