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DAX Virtual Audio

Status

Status: Supported · Applies to: FlexRadio · Platforms: Linux, macOS

DAX (Digital Audio eXchange) creates virtual audio devices on your computer that digital-mode programs (WSJT-X, fldigi, JS8Call, VARA and others) use as their sound card. Receive audio flows from a slice to the program, and the program's transmit audio flows back to the radio, all through AetherSDR with no cables.

DAX is a FlexRadio feature. On other radio families the DAX applet, menu entry and overlay button are hidden; use the TCI Server for audio there.

Requirements​

PlatformDAX
LinuxBuilt in. Needs PipeWire. Receive channels are native PipeWire streams; they also show up through PipeWire's PulseAudio and JACK layers.
macOSBuilt in, through the DAX Virtual Audio Driver that ships in the AetherSDR DMG; install it from there. If it is missing, enabling DAX shows "DAX Audio Driver Missing".
WindowsNo built-in DAX driver. The DAX applet says "No built-in DAX driver on Windows. Use TCI, or SmartSDR DAX." Use the TCI Server (audio and CAT over one connection), or FlexRadio's own SmartSDR DAX.

Setup​

Turning DAX on​

  • The DAX Audio applet (applet-tray button DAX) has a DAX: Enabled / Disabled button at the bottom.
  • Settings → Autostart DAX with AetherSDR is the same setting: while it is on, DAX starts every time you connect. This menu entry is not shown on Windows.

Assigning a slice to a DAX channel​

The radio sends a slice's audio to the DAX channel set on that slice. Choose it on the slice's VFO widget → DAX tab (DAX Ch). The channel list follows the radio's capacity, and a slice on a channel the radio cannot back shows Off.

The panadapter overlay's DAX flyout is for IQ instead: it holds IQ Ch and the WFM button (see DAX IQ Streaming).

Checking the devices (Linux)​

pactl list sources short | grep aethersdr   # DAX 1..N capture devices
pactl list sinks short   | grep aethersdr   # TX device

Stale devices left by a crash are cleaned up the next time DAX starts.

Using DAX​

Transmit audio​

When a digital program transmits in a digital mode (DIGU, DIGL), its audio from AetherSDR TX goes to the radio. Voice modes use your microphone. You don't switch anything by hand.

Wiring WSJT-X (Linux and macOS)​

  1. Put the slice in DIGU and set its DAX channel to 1.
  2. Turn DAX on, and turn on a Rigctld CAT port (see CAT Control).
  3. In WSJT-X, File → Settings → Audio: Input AetherSDR DAX 1, Output AetherSDR TX.
  4. Settings → Radio: Rig Hamlib NET rigctl, Network Server 127.0.0.1:4532, PTT Method CAT.

Full walk-through: WSJT-X Integration.

Other programs​

ProgramModesAudio inAudio outRig control
WSJT-X / JTDXFT8, FT4, JT65, Q65, WSPRAetherSDR DAX nAetherSDR TXRigctld CAT port, or TCI
fldigiPSK, RTTY, MFSK, CW, …AetherSDR DAX nAetherSDR TXRigctld CAT port
JS8CallJS8AetherSDR DAX nAetherSDR TXRigctld CAT port
VARA HF/FMVARAAetherSDR DAX nAetherSDR TXRigctld CAT port
Dire WolfAPRS, packetAetherSDR DAX nAetherSDR TX—

For packet and APRS you may not need an external modem at all: see AetherModem Packet Radio.

Two programs on two slices​

Give each program its own DAX channel and its own CAT port (with a different VFO A slice).

Reference​

Devices​

AetherSDR offers up to eight RX channels plus one TX channel. The number of RX channels follows the connected radio's slice capacity (for example 8 on a FLEX-6700, 4 on a FLEX-6600 or 8600, 2 on a FLEX-6300 or 6400). Rows and devices above that number are not shown.

DeviceDirectionPurpose
AetherSDR DAX 1 … DAX 8Capture (input)Receive audio from whichever slice is assigned that DAX channel
AetherSDR TXPlayback (output)Transmit audio to the radio

The DAX Audio applet​

Each RX row shows DAX n:, the slice currently assigned to that channel (or "—"), and a combined level meter and gain slider. The TX: row shows which slice holds transmit and the gain applied to audio coming from your program. Gains are saved per channel.

Known issues​

  • On macOS, a digital-mode program's transmit audio can reach the AetherSDR TX meter while the radio sends no RF (#4554).
  • On macOS, DAX transmit can stop sending audio to the radio altogether until AetherSDR is restarted (#5870).
  • On macOS with a FLEX-8000-series radio, DAX receive audio can come out chopped and very quiet (#3837).

Troubleshooting​

The program hears no audio​

The slice has no DAX channel, or the program is reading a different device.

  1. On the slice's VFO widget → DAX tab, set a DAX Ch.
  2. In the program, choose the matching AetherSDR DAX n input.
  3. On Linux, pactl list source-outputs shows which device each program is reading.

Transmit audio does not reach the radio​

The program sends to the wrong device, or the TX slice is in a voice mode.

  1. Set the program's audio output to AetherSDR TX.
  2. Put the TX slice in a digital mode (DIGU or DIGL).

A DAX row is missing​

The connected radio has fewer slices than that channel number, so AetherSDR does not show it. Use a lower channel number.

WSJT-X shows "Error in Sound Input"​

DAX was switched off while WSJT-X was using it.

  1. Turn DAX back on.
  2. Restart WSJT-X.

There is no DAX on Windows​

AetherSDR ships no DAX driver on Windows.

  1. Use the TCI Server, which carries audio and CAT over one connection, or FlexRadio's own SmartSDR DAX.

See also​