Enable APD to Linearise the Transmitter¶
APD (Adaptive Pre-Distortion) reduces transmitter non-linearity by applying a correction equaliser to the signal before it reaches the PA. Enable it to improve spectral purity, particularly on SSB and digital modes.
Before you start¶
- AetherSDR must be connected to the radio. APD is a radio-side function and requires an active connection.
- Open the TX Controls applet. If it is not visible, click the TX tray button on the right sidebar.
Steps¶
- Locate the APD button at the bottom of the TX Controls applet.
- Click APD to toggle adaptive pre-distortion on. The button background changes to green when enabled.
- Watch the status indicators to the right of the button:
- Cal lights green while the radio is collecting calibration data.
- Avail lights green when a calibration is complete but not yet applied.
- Active lights green when the equaliser is applied to the transmit signal.
- To turn APD off, click APD again. The button returns to its unlit state and all three indicators go dim.
What each control does¶
| Control | Kind | Behavior |
|---|---|---|
| APD | Toggle button | Enables or disables adaptive pre-distortion on the radio. Green when on, unlit when off. |
| Active | Indicator | Lit green when APD is on and the equaliser is actively applied to the signal. |
| Cal | Indicator | Lit green when APD is on and the radio is still calibrating. |
| Avail | Indicator | Lit green when APD is on and a calibration is available but not yet applied. |
The normal progression after enabling APD is: Cal → Avail → Active.
Tips¶
- APD calibration takes place automatically after you enable it. You do not need to transmit manually to trigger it; wait for the indicators to step through Cal → Avail → Active.
- If you disable and re-enable APD, the calibration sequence restarts from Cal.
ATU button behaviour¶
Starting with v0.9.5.1, the ATU button uses a per-frequency toggle that mirrors SmartSDR behaviour:
- First click (or any click after a frequency change): starts a new ATU tune cycle.
- Second click at the same frequency, when the ATU reports a successful match: switches the tuner to bypass.
- Click after any frequency change: always starts a fresh tune cycle, even if the previous status was successful.
The bypass state is cleared automatically when the transmit frequency changes, so the next click will start a new tune rather than bypassing. There is no change to the ATU button label or appearance; the Success, Byp, and Mem indicators below the button continue to reflect ATU status as before.
| Indicator | Kind | Behavior |
|---|---|---|
| Success | Indicator | Lights green when the ATU reports a successful or OK match. |
| Byp | Indicator | Lights orange when the ATU is in bypass or manual bypass. |
| Mem | Indicator | Lights green when the ATU is using a stored memory. |
MOX button and Quindar tones (v0.9.7)¶
In v0.9.7, clicking MOX routes through the Quindar-tone coordinator rather than toggling the transmitter directly. This means:
- Engage (click MOX on): if Quindar is enabled in the Audio Channel Strip and the active TX slice is on a phone mode, the K-tone plays before the transmitter keys.
- Disengage (click MOX off): the BK-tone plays after the transmitter unkeys.
- If Quindar is disabled, or the active TX slice is not on a phone mode, MOX behaves as before and keys the transmitter immediately.
The button appearance is unchanged: the MOX button turns red while the transmitter is keyed and returns to its unlit state when the transmitter is off.
| Control | Kind | Behavior |
|---|---|---|
| MOX | Toggle button | Toggles manual transmit. In v0.9.7, routes through the Quindar-tone coordinator so K/BK tones play on PTT engage/disengage in phone modes when Quindar is enabled. Button goes red while TX is keyed. |