VFO Panel Reference

The VFO panel is a floating per-slice control panel anchored to the VFO marker on the spectrum display. It provides quick access to the most frequently used per-slice settings — mode, filter presets, antenna selection, AF gain, pan, squelch, AGC, RIT/XIT, DSP noise reduction buttons, and DAX assignment — without leaving the spectrum view. Collapses to a compact frequency-only strip.

Before you start

• AetherSDR must be connected to the radio. The VFO panel requires an active radio connection.
• The DAX audio bridge must be running. If it is not, enable it via Settings > Autostart DAX with AetherSDR and restart AetherSDR, or start it manually.
• The VFO panel for the target slice must be open and expanded. If it is collapsed to the frequency-only strip, click anywhere on it to expand it.

Opening the VFO panel

Click the VFO marker flag on the spectrum display for the slice you want to configure. The VFO panel opens, anchored to the left of the marker.

VFO panel controls

Control	Location	Default	Valid values	Behavior
RX antenna button	Header	—	—	Opens antenna selection menu for the receive antenna of this slice.
TX antenna button	Header	—	—	Opens antenna selection menu for the transmit antenna of this slice.
Frequency display	Header	—	—	Shows the current slice frequency. Click once to begin direct frequency entry; type MHz and press Enter or Tab.
Filter width label	Header	—	—	Shows current filter bandwidth. Click to cycle through filter preset buttons in the Mode tab.
Collapse toggle	Header	expanded	—	Collapses the VFO panel to a compact frequency-only strip. Persisted per slice as SliceFlagCollapsed_{N}.
Marker thickness button	Header	1 px	Off, 1 px, 3 px	Cycles the VFO marker line through Off, 1 px, and 3 px. Persisted per slice as Slice{N}_MarkerWidth.
Filter edges button	Header	shown	—	Toggles the filter edge lines on the spectrum passband. Persisted per slice as Slice{N}_FilterEdgesHidden.
AF Gain slider	Audio tab	100	0–100	Sets the audio output level for this slice. Not persisted — reflects live radio state.
Pan slider	Audio tab	50	0–100	Sets left/right stereo pan for this slice. 50 = centre.
Mute button	Audio tab	off	—	Mutes audio output for this slice without changing the AF gain setting.
Squelch button + slider	Audio tab	off	0–100	Enables squelch for this slice. The adjacent slider sets the threshold.
AGC combo	Audio tab	FAST	FAST, MED, SLOW, OFF	Sets the AGC attack/release speed for this slice.
Mode combo	Mode tab	USB	USB, LSB, CW, CWL, AM, SAM, DIGU, DIGL, FM, NFM, DFM, RTTY	Sets the demodulation mode for this slice.
Filter preset buttons	Mode tab	—	—	Applies a saved filter width preset. Right-click to save the current filter width into that slot. Persisted in FilterPresets.
RIT / XIT buttons + labels	X/RIT tab	off	—	Enables receiver (RIT) or transmitter (XIT) incremental tuning. The label shows the current offset; scroll-wheel adjusts in 10 Hz steps.
DAX channel combo	DAX tab	Off	Off, 1–8	Assigns a DAX audio channel to this slice.
DSP buttons	DSP tab	off	—	Enables the corresponding noise reduction algorithm for this slice. Button availability depends on radio series and build. Right-click NR2, NR4, MNR, or DFNR to open the AetherDSP Settings dialog for that algorithm.
ADSP button	DSP tab	—	—	Opens the AetherDSP Settings dialog (client-side NR2 / NR4 / DFNR / RN2 / BNR / MNR). Styled like a radio-side DSP toggle but non-checkable. Click raises and focuses the modeless AetherDSP Settings dialog.
AetherVoice button	DSP tab	—	—	Toggles the Aetherial Audio Channel Strip — the unified TX/RX DSP suite. Spans 2 columns in the 4-column DSP grid.

Indicators

Indicator	States	Meaning
TX badge	TX (red), hidden	Shown when this slice is the active transmit slice.
SPLIT badge	SPLIT (amber), hidden	Shown when TX is assigned to a different slice than the active receive slice.

Assigning a DAX channel

1. Click the DAX tab inside the VFO panel.
2. Click the DAX channel combo and select a channel from the drop-down list.
3. To disable DAX routing for this slice, select Off.

The DAX channel combo assigns a DAX audio channel to the current slice. Selecting a numbered channel routes the slice's received audio to that DAX channel. Selecting Off removes the assignment. This setting reflects live radio state and is not persisted locally by AetherSDR.

Squelch behavior by mode

The squelch button and slider are automatically disabled in modes where squelch is not meaningful or supported:

• Squelch is disabled in Digital, RTTY, and CW modes.
• Digital / RTTY: Audio feeds external decoders via DAX; squelch is not meaningful and can gate weak FSK signals.
• CW: The radio locks squelch on at a fixed level and rejects changes.
• If squelch was enabled when switching into one of these modes, the radio turns it off automatically. The saved squelch state is preserved and will be restored if you switch back to a supported mode.

DSP tab controls

The DSP tab in the VFO panel contains radio-supplied noise reduction buttons and two client-side launcher buttons.

Radio-side DSP buttons

The following radio-side DSP buttons appear in the DSP tab grid:

Button	Algorithm
NR	Noise reduction
NB	Noise blanker
ANF	Automatic notch filter
APF	Audio peaking filter (CW mode only)
NRL	Noise reduction level
NRS	Spectral subtraction
RNN	RNN noise reduction
NRF	Spectral noise filter
ANFL	LMS notch filter
ANFT	FFT notch filter

Client-side launcher buttons

Two client-side launcher buttons appear at the end of the DSP grid:

Button	Behavior
ADSP	Opens the AetherDSP Settings dialog (client-side NR2 / NR4 / DFNR / RN2 / BNR / MNR). Styled like a radio-side DSP toggle but non-checkable. Click raises and focuses the modeless AetherDSP Settings dialog.
AetherVoice	Toggles the Aetherial Audio Channel Strip — the unified TX/RX DSP suite. Spans 2 columns in the 4-column DSP grid.

Client-side noise reduction toggles

The following client-side noise reduction buttons appear in the DSP tab when enabled by the radio series and build:

Button	Algorithm
NR2	Client-side noise reduction algorithm 2
NR4	Client-side noise reduction algorithm 4
RN2	Client-side noise reduction algorithm RN2
MNR	Client-side noise reduction algorithm MNR
DFNR	Client-side noise reduction algorithm DFNR
BNR	Client-side noise reduction algorithm BNR
NRL	Noise reduction level
NRS	Spectral subtraction
RNN	RNN noise reduction
NRF	Spectral noise filter

Right-click NR2, NR4, MNR, or DFNR to open the AetherDSP Settings dialog for that algorithm.

DSP level slider

A shared level slider row appears below the button grid. The slider adjusts the strength of whichever leveled DSP button was most recently turned on. The label to the left of the slider shows the active target (for example, NR or NB). The numeric value is shown to the right.

The slider range is 0–100. When no leveled DSP is active — or when only RNN, ANFT, or APF is on — the slider row is dimmed and does not respond to input. The row remains in place at all times; it does not shift the button grid when its target changes.

Algorithms that support the level slider: NR, NB, ANF, NRL, NRS, NRF, ANFL.

When a leveled DSP algorithm is enabled from the radio's saved profile on startup, the level slider is automatically populated without requiring a manual toggle.

Filter width label

The filter width label shows the current filter bandwidth. Click to cycle through filter preset buttons in the Mode tab. The label uses RxApplet::formatFilterWidth as the single source of truth, fixing a 0.1 kHz offset that affected SSB/digital mode readouts.

RX and TX antenna menus

The RX antenna button opens a menu to select the receive antenna for this slice. The TX antenna button opens a menu to select the transmit antenna. These menus use the slice's radio-provided antenna list when available, falling back to the global antenna list. TX antenna options automatically exclude RX-only antenna ports. Each menu item shows its raw antenna name as a tooltip.

Marker controls

The Marker thickness button cycles the VFO marker line through Off, 1 px, and 3 px. The setting is persisted per slice as Slice{N}_MarkerWidth.

The Filter edges button toggles the filter edge lines on the spectrum passband. The setting is persisted per slice as Slice{N}_FilterEdgesHidden.

Collapse toggle

The Collapse toggle collapses the VFO panel to a compact frequency-only strip. The setting is persisted per slice as SliceFlagCollapsed_{N}.

Slice badge

The slice badge shows the slice letter. The badge supports rich text formatting, allowing special characters.

Frequency entry

Click the frequency display to begin direct frequency entry. Type the frequency in MHz and press Enter or Tab.

• On XVTR bands, the frequency range is extended to 50000.0 MHz.
• For 2m/70cm bands (100-999 MHz range), a bare integer like 1446 is automatically interpreted as 144.6 MHz by inserting a decimal after the third digit.
• For 23cm and microwave bands, a bare integer represents MHz directly.
• When you explicitly enter a frequency above 54 MHz (e.g., typing "144.225"), the parser correctly treats it as MHz even without an XVTR slice, allowing direct VHF/UHF entry.

If you attempt a direct frequency entry while the VFO is locked, the entry is cancelled and the LOCKED overlay is shown instead of accepting the new frequency. Scroll-wheel tuning on a locked VFO triggers the same feedback — the slice model notifies tuneBlockedByLock, which cancels any in-progress frequency entry and repaints the LOCKED indicator.

The frequency entry field uses a custom FreqLineEdit widget. The hint text reads "MHz (e.g. 14.225)". The frequency display also provides accessibility announcements when the frequency changes, ensuring screen reader compatibility.

VFO lock behavior

The Lock VFO button toggles the locked state of the VFO. When locked: - Scroll-wheel tuning is blocked — the slice model shows feedback via tuneBlockedByLock. - Direct frequency entry is cancelled when attempting to begin or during an active entry. - The frequency display shows a LOCKED overlay (🔒 symbol) instead of the frequency value during direct entry attempts.

Unlocking clears the LOCKED overlay centrally in the SliceModel.

Tab layout

The VFO panel tab stack reports only the current tab's preferred size. This fixes a visual gap inside the Mode tab when the DSP tab is taller (due to the digContainer being visible in DIGU/DIGL modes). The tab content no longer over-allocates height from the maximum of all pages.

Tab navigation

The VFO panel tabs are implemented as QPushButton widgets instead of QLabel widgets. This change provides proper keyboard focus support:

• Each tab button is focusable via the Tab key (Qt::TabFocus policy).
• Focused tabs show a subtle bottom border outline using the tab label colour.
• Right-click on the speaker tab (first tab) toggles the audio mute state directly — a convenient shortcut to mute the slice without opening the Audio tab.

The tab buttons use flat, checkable style with the same visual appearance as before. The active tab is styled with the accent colour (#00b4d8) and a bottom border.

Scroll wheel behavior

The scroll wheel direction in the VFO panel respects the Reverse mouse wheel setting. If you have enabled reverse mouse wheel in Settings > Audio/Radio > Tuning, scrolling the VFO panel wheel will tune in the opposite direction. This setting is checked via the InteractionSettings model and applied to all VFO panel wheel events.

The scroll wheel behaviour is fully integrated with the InteractionSettings configuration. If you reverse the mouse wheel in settings, the VFO panel scroll direction reverses accordingly. This applies to all wheel events on the VFO panel, including the frequency display area and the RIT/XIT offset labels.

Accessibility

The VFO panel provides accessibility announcements for frequency changes. When the frequency changes while an accessibility client (screen reader) is active, a QAccessibleValueChangeEvent is posted for