FreeDV on FLEX 6000/8000/Aurora with no external hardware

Howard K7JNX

I was inspired by the earlier post by Mike VA3MW RADEv2 (FreeDV v2) on FLEX-6000/8000/Aurora with RPI, but I wished for a Intel architecture version of the FreeDV-Flexradio appimage to appear so that the RPi was not needed. This happened a few days ago. (I don't know who developed this appimage but my hat is off to them. If and when I find out I would love to acknowledge him here.)

The key is to use WSL2 (Windows subsystem for Linux) to run that appimage in the same Windows 11 machine that is being used to run SmartSDR.

Here I have tried to document how I set it up and got it working properly. Over the air QSOs this morning have confirmed proper operation.

If you encounter problems or have additions to suggest, let me know and I will revise the guide accordingly.

Guide: Running FreeDV-Flex on Windows 11 via WSL2

1. Prerequisites

• Windows 11 (Version 22H2 or higher).
• Ubuntu 24.04 LTS installed in WSL. (See the Appendices if you need to install it.)
• FlexRadio 6000/8000/Aurora on the same local network.

2. Configure WSL Networking

Windows 11 "Mirrored Networking" is required to allow the radio's UDP streams to reach the Linux environment.

1. Navigate to your Windows user folder (e.g., C:\Users\YourName\).
2. Create (or edit) a file named .wslconfig (note the prefix period and lack of filetype) It must contain:

[wsl2]
networkingMode=mirrored
dnsTunneling=true
firewall=true

3. Restart WSL by running this in PowerShell

wsl --shutdown

3. Prepare the Ubuntu Environment

Open your Ubuntu 24.04 terminal and run:

# Update system and install required libraries
sudo apt update && sudo apt upgrade -y
sudo apt install -y libfuse2t64 libpulse0 libasound2t64 wget

4. Install the FreeDV-Flex AppImage

Run the following commands from the Ubuntu 24.04 terminal:

wget https://github.com/drowe67/freedv-gui/releases/download/v2.2.1/FreeDV-FlexRadio-2.2.1-x86_64.AppImage
chmod +x FreeDV-FlexRadio-2.2.1-x86_64.AppImage

5. Create the Launch Script

Because of the way WSL handles network interfaces and environment variables, using a script is the most reliable way to connect.

• Create a file named fdv.sh by running

nano fdv.sh

• Paste the following (replace the IP with your Radio's IP and AA00 with your gridsquare):

#!/bin/bash
# IMPORTANT: Use 'export' so the application can see the variable
export SSDR_RADIO_ADDRESS=192.168.1.193

# Run the AppImage with your station details
./FreeDV-FlexRadio-2.2.1-x86_64.AppImage -m "Your Name + Location" -l AA00 -t 120

6. Create Windows shortcut to launch the script

• Select New > Shortcut.
• In the "Type the location of the item" box, enter the following command (assuming your script is named fdv.sh and is in your Ubuntu home directory):

wsl.exe ~ -e ./fdv.sh

• Click Next.
• Type a name for the shortcut, like "FreeDV FlexRadio".
• Click Finish.

Critical Radio Settings

Unlike other digital modes (like FT8), this application handles the VITA-49 streams directly.

• DAX MUST BE OFF: Ensure the DAX button on your active Slice is unselected.
• Mode: Set your Slice to DIGU or DIGL as appropriate.

Troubleshooting

"No Radios Found"

• Check for VPNs: Fully exit Tailscale or other VPNs. They often intercept the UDP traffic even if the firewall is off.
• Interface Binding: If your 192.168.x.x IP is on eth1, add export SSDR_INTERFACE_ADDRESS=<Your_Ubuntu_IP> to your script.

Windows Firewall

If communication is blocked, run this in PowerShell (Admin):

New-NetFirewallRule -DisplayName "WSL Flex" -Direction Inbound -Action Allow -Protocol UDP -LocalPort 4991-4999

Appendix A: Installing WSL and Ubuntu 24.04 from Scratch

If you do not already have Linux running on your Windows machine, follow these steps to get a clean installation of Ubuntu 24.04 LTS.

1. Enable WSL and Install Ubuntu

Windows 11 makes this process very straightforward via the command line.

1. Open PowerShell or Command Prompt as an Administrator (Right-click the Start button and select Terminal (Admin) or PowerShell (Admin)).
2. Type the following command to see available distributions

wsl --list --online

1. Install Ubuntu 24.04 vy running:

wsl --install -d Ubuntu-24.04

2. Complete the Linux Setup

1. Once the installation finishes, Windows will prompt you to Restart your computer.
2. After restarting, a Linux terminal window will open automatically to finish the installation.
3. Enter a Username: This does not have to match your Windows username.
4. Enter a Password: You will not see characters appear as you type; this is normal security behavior.

3. Verify the Version

To ensure you are on the correct version (24.04), type the following in your new Ubuntu window:

lsb_release -a

You should see: Description: Ubuntu 24.04 LTS.

Appendix B: Troubleshooting the Installation

Error: "The virtual machine platform remains unenabled"

If you get an error regarding the "Virtual Machine Platform," you may need to enable virtualization in your computer's BIOS/UEFI.

• Look for settings labeled VT-x (Intel), AMD-V (AMD), or SVM.
• Ensure they are set to Enabled.

Ensure WSL 2 is the Default

Some older Windows installations might default to WSL 1. For the "Mirrored Networking" required by the FlexRadio, you must be on WSL 2. Check this in PowerShell:

wsl --set-default-version 2

Updating an existing WSL to 24.04

I had originally tried running with an old version 22.04 and it failed miserably! If you already have an older version of Ubuntu (like 22.04) and want a fresh 24.04 instance specifically for your radio tools, you can run:

wsl --install -d Ubuntu-24.04

This will install 24.04 alongside your old version. You can switch between them or set 24.04 as the default using:

wsl --set-default Ubuntu-24.04