Skip to content

Setting up digital modes (FT8, WSJT-X, fldigi)

This page explains how to connect WSJT-X, fldigi, or similar digital-mode software to AetherSDR so they can receive audio from the radio, send audio back for TX, and control the VFO. You need two bridges running in AetherSDR: DAX (audio) and CAT (frequency and mode control).

Before you start

  • AetherSDR is connected to the FLEX-8600 and at least one slice is active.
  • WSJT-X, fldigi, or your chosen digital-mode application is installed.
  • You know which slice letter (A, B, C, …) you intend to use for digital modes.

Steps

Part 1 — Enable DAX audio

  1. Click the DAX tray button on the right sidebar. The DAX Audio applet opens.
  2. Click Enable. The button turns green. AetherSDR starts the DAX audio bridge and persists the setting as AutoStartDAX.
  3. Note the slice shown in the Slice-assignment status indicator next to the DAX channel you want to use (e.g., "Slice A" next to DAX 1:). If it shows —, assign the slice to a DAX channel in your radio's slice settings before continuing.
  4. Optionally adjust the DAX 1 gain+meter slider for your RX channel. Default is 0.5; valid range is 0.0–1.0. This is persisted as DaxRxGain1 (or DaxRxGain2–DaxRxGain4 for other channels).
  5. Optionally adjust the TX gain+meter slider. Default is 0.5; valid range is 0.0–1.0. Persisted as DaxTxGain.
  6. To start DAX automatically on every launch, go to Settings > Autostart DAX with AetherSDR and check that item.

Part 2 — Enable CAT control

  1. Click the CAT tray button on the right sidebar. The CAT Control applet opens.
  2. Check the Base port field. Default is 4532. Channels A–D bind to ports 4532, 4533, 4534, 4535. Valid range is 1024–65535. Change the value if another application already uses port 4532.
  3. Click Enable TCP. The button turns green. All four rigctld-compatible TCP servers start.
  4. On Linux or macOS, click Enable TTY if your application requires a serial-style port. PTY symlinks appear at /tmp/AetherSDR-CAT-A, /tmp/AetherSDR-CAT-B, /tmp/AetherSDR-CAT-C, /tmp/AetherSDR-CAT-D.
  5. To start CAT automatically on every launch, go to Settings > Autostart CAT with AetherSDR and check that item.

Part 3 — Configure your digital-mode application

WSJT-X

  1. In WSJT-X, open Settings > Radio.
  2. Set Rig to Hamlib NET rigctl.
  3. Set Network Server to localhost:4532 (or the port matching your chosen slice channel).
  4. Open Settings > Audio and set the Input and Output devices to the DAX channel assigned to your slice (e.g., DAX 1).

fldigi

  1. In fldigi, open Configure > Rig Control > Hamlib.
  2. Set Device to Net rigctl and Port/Address to localhost:4532.
  3. Open Configure > Sound Card and select the DAX channel for input and output.

What each control does

Control Default Range Setting key
Enable (DAX) off on/off AutoStartDAX
DAX 1 gain+meter 0.5 0.0–1.0 DaxRxGain1
DAX 2 gain+meter 0.5 0.0–1.0 DaxRxGain2
DAX 3 gain+meter 0.5 0.0–1.0 DaxRxGain3
DAX 4 gain+meter 0.5 0.0–1.0 DaxRxGain4
TX gain+meter 0.5 0.0–1.0 DaxTxGain
Enable TCP (CAT) off on/off —
Enable TTY (CAT) off on/off —
Base (CAT TCP port) 4532 1024–65535 CatTcpPort

Tips

  • Each CAT channel (A/B/C/D) controls one slice. If you run two digital-mode programs simultaneously, point the second program at port 4533 and assign it to Slice B with a second DAX channel.
  • If you enter an out-of-range value in the Base field, it resets to 4532 automatically.
  • The per-channel TCP status indicator in the CAT applet shows how many clients are connected (e.g., :4532 (1 client)). Use this to confirm WSJT-X has connected successfully.

Troubleshooting

  • WSJT-X reports "Rig not found" or connection refused — Confirm Enable TCP is active (button is green) and the port in WSJT-X matches the Base value in AetherSDR. Check that no firewall is blocking localhost connections.
  • No audio decoded in WSJT-X / fldigi — Confirm Enable in the DAX applet is active. Check that the slice-assignment status next to the DAX channel you selected shows your slice letter and not —. Verify the audio input device in your digital-mode application is set to the correct DAX channel.
  • TX audio not reaching the radio — Check the TX gain+meter slider is not at 0.0. Confirm the TX slice indicator in the DAX applet shows your active slice.
  • PTY symlinks not appearing (Linux/macOS) — Confirm Enable TTY is active. The paths /tmp/AetherSDR-CAT-A through /tmp/AetherSDR-CAT-D are created when TTY is enabled and the radio is connected.
⚡ Athena AetherSDR Assistant
Hi! I'm Athena, the AetherSDR AI assistant. Ask me anything about installation, configuration, or troubleshooting.