Summary

The APD (Adaptive Pre-Distortion) Active / Cal / Avail status indicators in the TX applet need further investigation to accurately reflect the radio's APD state.

Current State

• APD enable/disable toggle works (apd enable=0|1)
• Radio sends equalizer_active=0|1, configurable=1, linearity, sample_index, and insanity messages
• Indicators update but mapping may not match SmartSDR behavior

What We Know from FlexLib

public bool EqualizerActive { get; set; }              // → "Active"
public bool EqualizerCalibrating => !EqualizerActive;  // → "Cal" (computed: !Active)
public bool Available { get; set; }                     // → "Avail" (never set in FlexLib)

• Active and Cal are mutually exclusive (Cal = !Active)
• Avail is never set in FlexLib — derived in the SmartSDR WPF UI layer (which we don't have)
• Only one indicator should be lit at a time
• All indicators off when APD is disabled

Observed Radio Behavior

• equalizer_active jumps from 0→1 after first TX (no intermediate state)
• linearity score (0–1) appears before equalizer_active flips
• sample_index increments with each TX while refining the equalizer
• insanity messages list quality issues during calibration
• mmx=0 field never changes (purpose unknown)
• configurable=1 is always present on FLEX-8600

Open Questions

1. What exactly drives the Avail indicator in SmartSDR?
2. Should insanity messages or linearity score affect indicator state?
3. Does mmx play a role in the state machine?
4. Is configurable the gate for Avail, or something else?

Related Files

• src/gui/TxApplet.cpp — indicator display logic
• src/models/TransmitModel.h/.cpp — APD state tracking
• reference/FlexLib/FlexLib/APD.cs — FlexLib reference implementation