Change mode (USB, LSB, CW, AM, FM, etc.)¶
This page explains how to select a receive mode for a slice. Changing the mode reshapes the filter presets and tuning step sizes to suit the new modulation.
Before you start¶
- AetherSDR must be connected to the radio. The RX Controls applet requires an active radio connection.
- If you have more than one slice, select the correct slice first using the A..H tab row at the top of the RX Controls applet.
Steps¶
- If the RX Controls applet is not visible, click the RX tray button on the right sidebar to show it.
- If your radio has more than one slice active, click the appropriate slice tab (A through H) to bind the applet to the slice you want to change.
- Click the Mode combo drop-down. The current mode is shown (default: USB).
- Select the desired mode from the list:
- USB, LSB, CW, AM, SAM, FM, NFM, DFM, DIGU, DIGL, RTTY
- (RADE appears only in builds with RADE support enabled.)
- The slice switches to the selected mode. The filter width presets and tuning step sizes update automatically to suit the new mode.
- If you want to use the software WFM demodulator, click the WFM button (see below for details).
WFM (Software FM Demodulator)¶
The WFM button provides a software-based wideband FM demodulation mode. This is not a radio mode – it uses the DAX IQ stream from the slice and routes demodulated audio through the system's Hi-Fi Cable or similar virtual audio device.
When WFM is active: - The WFM button lights green. - The mode combo shows the last selected radio mode (e.g., USB) but the WFM demodulator overrides the radio's audio path. - The slice's audio is demodulated in software, allowing reception of broadcast FM (88–108 MHz) and other wideband FM signals.
When you change modes: - Selecting any real radio mode (USB, LSB, CW, etc.) automatically deactivates the WFM demodulator. - The WFM button state updates to reflect that WFM is no longer active on this slice.
When exiting WFM: - Click the WFM button again to deactivate it. The slice returns to normal radio-mode audio.
Limitations: - WFM requires a DAX IQ channel to be active on the slice. - The Hi-Fi Cable or equivalent virtual audio device must be configured as the DAX output. - WFM is not a radio mode – it does not affect the radio's mode or filter settings.
What each control does¶
| Control | Default | Valid values |
|---|---|---|
| Slice tabs (A..H) | — | 1–8 buttons (capped by hardware max slices). Row hidden if maxSlices ≤ 1. |
| Slice badge | A | A/B/C/D/E/F/G/H, coloured by slice identity. |
| 🔓 / 🔒 | 🔓 (unlocked) | Toggle button. Toggles tune-lock on the slice; locked slice ignores frequency changes. |
| Mode combo | USB | USB, LSB, CW, AM, SAM, FM, NFM, DFM, DIGU, DIGL, RTTY (+ RADE if available) |
| WFM | Off | Toggle button. Enables software FM demodulation via DAX IQ. Overrides radio audio path. |
| Frequency label | 0.000.000 | Displays current VFO frequency with dotted grouping. Click to edit. |
| Frequency edit | — | Enter MHz (0.001–54.000 MHz, up to 50000 MHz on XVTR). Escape cancels and restores previous frequency. |
| STEP | 100 Hz (index 2) | Per-mode list (e.g. SSB: 1, 10, 50, 100, 500, 1000, 2000, 3000 Hz; CW: 1, 5, 10, 50, 100, 200, 400 Hz; FM family: 50–12500 Hz) |
| Filter width presets | Mode-dependent | USB/LSB: 1800/2100/2400/2700/2900/3300 Hz; CW: 50/100/250/400/500/600 Hz; AM/SAM: 5600–14000 Hz; DIGU/DIGL: 100–2000 Hz; RTTY: 250–1000 Hz. Hidden for FM/NFM/DFM. |
| Filter passband widget | — | Drag lo/hi edges to adjust filter passband. |
| Tone mode (FM) | Off | Off, CTCSS TX. Visible only in FM family modes. |
| CTCSS tone value | — | 41 standard EIA/TIA-603 tones (67.0 Hz to 254.1 Hz). Enabled only when Tone mode = CTCSS TX. |
| Offset (FM) | 0.0 MHz | Spinbox (0.0–100.0 MHz, step 0.1). Sets FM repeater offset frequency. |
| − (offset down) | — | Toggle button. Sets repeater offset direction to down (TX below RX). |
| Simplex | checked | Toggle button. Sets repeater offset to simplex (TX = RX). |
| + (offset up) | — | Toggle button. Sets repeater offset direction to up (TX above RX). |
| REV | — | Toggle button. Inverts the TX offset sign for reversed repeater pairs. |
| 🔊 / 🔇 (mute) | 🔊 (unmuted) | Push button. Single-click mutes/unmutes this slice. Double-click mutes/unmutes all owned slices. Icon flips when radio acknowledges. |
| AF gain | 70 | Slider (0-100) for slice audio output gain. |
| L / R pan | 50 (centre) | Slider (0-100) for stereo pan position. Double-click resets to centre. The slider fill now paints from centre outward for better visual feedback (v26.6.1). |
| SQL | Off | Toggle button to enable squelch. Auto-disabled in RTTY, DIGU, DIGL, NT, CW, and CWL modes. In RTTY and digital modes, squelch is also turned off automatically to prevent gating FSK signals (#2504). |
| Squelch level | 20 | Slider (0-100) to set squelch threshold. Disabled in RTTY, DIGU, DIGL, NT, CW, and CWL modes. |
| AGC mode | Med | Off, Slow, Med, Fast. Hidden in FM family modes. |
| AGC threshold | 65 | Slider (0-100). Sets AGC threshold (or AGC off-level when AGC mode is Off). Right-click to calibrate against the noise floor (see below). |
| RX antenna | ANT1 | Combo box listing available receive antennas. Populated from the radio's ant_list, the slice's rxAntennaList() when available, and virtual antenna tokens from KiwiSDR manager. Blue-coloured label. |
| TX antenna | ANT1 | Combo box listing TX-capable antennas. RX-only antenna ports (prefix 'RX') are filtered out. Red-coloured label. |
| TX (badge) | — | Toggle button. Click to set this slice as the TX slice. |
| RIT | — | Toggle button. Toggles Receive Incremental Tuning on/off. |
| RIT 0 | — | Push button. Zeroes the RIT offset. |
| RIT offset | +0 Hz | Spinbox (step 10 Hz). Adjusts RIT offset. |
| XIT | — | Toggle button. Toggles Transmit Incremental Tuning on/off. |
| XIT 0 | — | Push button. Zeroes the XIT offset. |
| XIT offset | +0 Hz | Spinbox (step 10 Hz). Adjusts XIT offset. |
| QSK | — | Indicator. Lights amber when CW break-in (QSK) is active. Read-only; controlled via CW applet. |
| Filter width label | 2.7K | Indicator. Shows current filter bandwidth (e.g., '2.7K', '3.3K', '500', '6.0K'). |
| REV / XFC | For FM repeater operation, REV inverts the TX offset sign to work a reversed repeater pair. On backends that support a transmit-frequency check, the button relabels to XFC: pressing it holds the transmit frequency check for the duration of the press, and while held it briefly forces the radio toward the transmit frequency to confirm coverage. | The button toggles REV (checkable) normally, or becomes a momentary XFC down-button when the connected radio backend advertises hasTransmitFrequencyCheck. The held XFC is released on hide, deactivate, capability change, or disconnect. |
| SQL / AUTO | Three-way cycle button: each click steps Off → SQL (manual threshold) → AUTO (algorithm tracks the noise floor) → Off. In AUTO mode the button shows amber 'AUTO'; in manual mode green 'SQL'. Disabled (and auto-turned off) in RTTY and digital modes (DIGU, DIGL) where squelch would notch out FSK characters (#2504). | Manual and Auto both turn the radio squelch on. The auto-squelch algorithm lives in the panadapter; the level is the dB margin above the measured noise floor. Mirrored by an identical button in the VFO panel's Audio tab. |
| ## AGC-T Noise Calibration |
The AGC threshold slider now supports a noise floor calibration feature. This helps you set an optimal AGC threshold based on the current noise floor.
To calibrate: 1. Right-click on the AGC threshold slider. 2. Select Calibrate AGC-T against noise floor… from the context menu. 3. The calibration process samples the noise floor and adjusts the AGC threshold slider to an appropriate level.
The right-click context menu is available regardless of the AGC mode setting. The tooltip on the slider now includes a reminder: "Right-click to calibrate against the noise floor".
Tips¶
- FM, NFM, and DFM modes do not show filter width preset buttons. The filter is fixed for those modes.
- After switching to FM or NFM, the CTCSS tone and repeater offset controls (Tone mode, Offset, −, Simplex, +, REV) become visible. See Work an FM repeater with CTCSS tone and ± offset for details.
- After switching to CW, the QSK indicator in the header becomes relevant. Its state is controlled from the CW applet, not from RX Controls.
- AGC mode controls are hidden when an FM family mode is active.
- Filter presets are now stored in a
lo:hiformat (e.g.300:3000) as well as the older plain-width format. Both formats are read correctly. If you have saved custom presets from an earlier version, they continue to work without any action on your part. - The
stepFilterWidth()method walks the per-mode preset list so widen/narrow shortcuts produce mode-correct edge geometry. This ensures that when you widen or narrow the filter using keyboard shortcuts, the filter stays within the appropriate preset boundaries for the current mode. - When switching to RTTY or digital modes (DIGU, DIGL), the squelch is automatically disabled and turned off. This prevents the squelch from notching out FSK characters and breaking decoding (#2504).
- The slice badge now supports rich text formatting (HTML) for the slice letter (#2606).
- The manual squelch level is now radio-authoritative and is not persisted client-side. When no slice is attached, the control falls back to its class default of 20. This follows the Radio-Authoritative Settings Policy (AGENTS