Background

Per-band settings persistence (band memory) was implemented in v0.2.0 but had a critical bug where the band-crossing detection fired during initial connection, saving incorrect state (e.g., 20m frequency saved under 80m/40m bands). The fix in v0.2.3 guarded with m_updatingFromModel but this didn't work because the flag was reset before the band-crossing code ran in the same lambda.

Band memory is currently deprecated — band switching always uses BandDef defaults, and any stale QSettings band data is cleared on launch.

What Needs to Be Redesigned

The core problem: automatically detecting band crossings from frequencyChanged signals is unreliable because:

1. The signal fires for both user-initiated and radio-status-driven frequency changes
2. During connect, the radio sends multiple frequency updates as slices are initialized
3. There's no reliable way to distinguish "user tuned across a band edge" from "radio reported its current frequency"

Proposed Approaches

Option A: Save only on explicit band button clicks

• Only save state when the user clicks a band button in the overlay menu
• Simple, no false triggers, but doesn't save state when user tunes manually across bands

Option B: Timer-based debounce

• After a frequency change, wait N seconds before saving band state
• Avoids saving during rapid status updates on connect
• Still risky during reconnect/auto-connect

Option C: Radio-side band stacking

• The radio may have its own band stacking registers (band_persistence_enabled=1 seen in radio status)
• Investigate if the radio handles per-band settings natively and we just need to read them

Settings to Persist Per Band

When redesigned, each band should save:

• Frequency, mode, RX antenna
• Filter width, AGC mode/threshold
• RF gain, WNB on/off + level
• Pan center, bandwidth, dBm range, FFT/waterfall split

Related Code

• src/models/BandSettings.h/.cpp — BandSnapshot struct, save/load/lookup (currently unused)
• src/models/BandDefs.h — shared band table with defaults
• src/gui/MainWindow.cpp — captureCurrentBandState(), restoreBandState() (currently unused)

References

• Original implementation: v0.2.0
• Bug: Band menu tunes to wrong frequency (80m/40m → 20m) #8 (band menu tunes to wrong frequency)
• Deprecation: v0.2.3

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