NetKeyer - FlexRadio CW Keyer

A cross-platform GUI application for CW (Morse code) keying with FlexRadio devices, supporting both serial port and MIDI input devices.

Download

Download pre-built binaries of NetKeyer now!

Features

Cross-Platform: Runs on Linux, Windows, and macOS using Avalonia UI
Radio Discovery: Automatic discovery of FlexRadio devices on the network
- Local network discovery
- SmartLink remote connection support
- Sidetone-only practice mode (no radio required)
Multiple Input Device Types:
- Serial port (HaliKey v1)
- MIDI devices (HaliKey MIDI, CTR2, and other MIDI controllers)
- Configurable MIDI note mappings for paddles, straight key, and PTT
CW Controls:
- Speed adjustment (5-60 WPM)
- Sidetone volume control (0-100)
- Pitch control (300-1000 Hz)
- Iambic Mode A/B selection
- Straight Key mode
- Paddle swap option
Local Sidetone Generation:
- Low latency audio using platform-optimized backends
- PortAudio for cross-platform compatibility
- WASAPI for Windows
PTT Support:
- Supports PTT keying for non-CW modes

Requirements

.NET 8.0 SDK
FlexRadio device on the network (or use sidetone-only mode for practice)
Input device:
- Serial port device (e.g., HaliKey v1/v2), OR
- MIDI controller (e.g., HaliKey MIDI, CTR2)

Building from Source

If you don’t want to use the pre-built binaries, you can build from source directly.

cd NetKeyer
dotnet build

Running

cd NetKeyer
dotnet run

Usage

Setup Page

SmartLink (Optional): Click “Enable SmartLink” to connect to remote radios via FlexRadio SmartLink
Select Radio:
- Click “Refresh” to discover FlexRadio devices
- Select a radio and GUI client station from the dropdown, OR
- Select “No radio (sidetone only)” for practice mode
Select Input Device Type: Choose between:
- Serial Port (HaliKey v1) - uses CTS (left) and DCD (right) pins
- MIDI (HaliKey MIDI, CTR2) - uses configurable MIDI note mappings
Choose Input Device:
- For Serial: Select the serial port connected to your keyer/paddle
- For MIDI: Select the MIDI device, then optionally click “Configure MIDI Notes…” to customize mappings
Connect: Click “Connect” to begin operating

Operating Page

Monitor Paddle Status: Visual indicators show left/right paddle state in real-time
Adjust CW Settings:
- Speed (WPM): Controls dit/dah timing
- Sidetone: Volume of local audio feedback
- Pitch: Frequency of sidetone tone
Select Keyer Mode:
- Iambic: Automatic dit/dah generation with Mode A or Mode B
- Straight Key: Direct on/off control
Swap Paddles: Reverse left/right paddle assignment if needed
Disconnect: Return to setup page to change settings

MIDI Configuration

The MIDI note configuration dialog allows you to assign any MIDI note (0-127) to one or more functions:

Left Paddle: Generates dits in iambic mode
Right Paddle: Generates dahs in iambic mode
Straight Key: Direct key on/off control
PTT: Push-to-talk for non-CW modes

Default mappings (compatible with HaliKey MIDI and CTR2):

Note 20: Left Paddle + Straight Key + PTT
Note 21: Right Paddle + Straight Key + PTT
Note 30: Straight Key only
Note 31: PTT only

Troubleshooting

Connection Issues

Radio not found:

Ensure radio is on the same network
Check firewall settings
Try SmartLink if local discovery fails

GUI client binding fails:

Radio needs SmartSDR or another GUI client running
Wait a moment after connecting before binding

Audio Issues

No sidetone:

Check sidetone volume slider
Verify system audio is not muted
Check audio output device in your system mixer

High latency:

Windows: Ensure WASAPI backend is being used
Linux: Check PulseAudio/PipeWire configuration
Adjust buffer size if needed

Input Device Issues

Serial port not found:

Check device permissions (Linux: add user to dialout group)
Verify device is connected
Click “Refresh” to rescan

MIDI device not responding:

Verify MIDI device is connected and powered
Check MIDI note mappings match your device
Use “Configure MIDI Notes…” to adjust mappings

Debug Logging

NetKeyer supports detailed debug logging controlled by the NETKEYER_DEBUG environment variable. This can help diagnose issues with specific subsystems.

Log File Location:

Debug messages are automatically written to a log file in the NetKeyer application data folder:

Windows: %APPDATA%\NetKeyer\debug.log
Linux: ~/.config/NetKeyer/debug.log
macOS: ~/Library/Application Support/NetKeyer/debug.log

You can easily access the log folder via Help → View Debug Log… in the application menu.

Note: On Windows, GUI applications don’t show console output when run outside a debugger. Debug messages are always written to the log file, making them accessible even when the console isn’t visible.

Available Debug Categories:

Category	Description
`keyer`	Iambic keyer state machine (paddle state, element timing, mode transitions)
`midi`	MIDI input parsing and raw event processing
`input`	Input abstraction layer (paddle state changes, indicator updates)
`slice`	Transmit slice mode monitoring (CW vs PTT mode detection)
`sidetone`	Audio sidetone provider (tone/silence state machine, timing)
`audio`	Audio device management (initialization, enumeration, selection)

Usage Examples:

Linux/macOS:

# Enable all debug output
NETKEYER_DEBUG=all dotnet run

# Enable specific categories
NETKEYER_DEBUG=keyer,midi dotnet run

# Enable all MIDI-related categories using wildcard
NETKEYER_DEBUG=midi* dotnet run

Windows PowerShell:

# Enable all debug output
$env:NETKEYER_DEBUG="all"
dotnet run

# Enable specific categories
$env:NETKEYER_DEBUG="keyer,midi"
dotnet run

Windows CMD:

# Enable all debug output
set NETKEYER_DEBUG=all
dotnet run

# Enable specific categories
set NETKEYER_DEBUG=keyer,midi
dotnet run

Common Debugging Scenarios:

Paddle not working: Use NETKEYER_DEBUG=input,keyer to see paddle state changes and keyer logic
MIDI issues: Use NETKEYER_DEBUG=midi,input to see raw MIDI events and parsed paddle states
Audio problems: Use NETKEYER_DEBUG=audio,sidetone to see device initialization and tone generation
Radio connection issues: Use NETKEYER_DEBUG=slice to see transmit mode detection

Developer Information

Project Structure

NetKeyer/
├── Views/                  # XAML UI layouts
├── ViewModels/             # Application logic and data binding
│   ├── MainWindowViewModel.cs
│   ├── MidiConfigDialogViewModel.cs
│   ├── AudioDeviceDialogViewModel.cs
│   └── AboutWindowViewModel.cs
├── Models/                 # Data models
│   ├── UserSettings.cs
│   ├── MidiNoteMapping.cs
│   └── AudioDeviceInfo.cs
├── Services/               # Core application services
│   ├── InputDeviceManager.cs
│   ├── KeyingController.cs
│   ├── RadioSettingsSynchronizer.cs
│   ├── SmartLinkManager.cs
│   └── TransmitSliceMonitor.cs
├── Audio/                  # Sidetone generation
│   ├── SidetoneGeneratorFactory.cs
│   └── ISidetoneGenerator.cs
│   ├── SidetoneGenerator.cs (PortAudio)
│   ├── WasapiSidetoneGenerator.cs (Windows WASAPI)
│   ├── SidetoneProvider.cs (waveform generation)
├── Midi/                   # MIDI input handling
│   └── MidiPaddleInput.cs
├── Keying/                 # Iambic keyer logic
│   └── IambicKeyer.cs
├── SmartLink/              # SmartLink authentication
│   ├── SmartLinkAuthService.cs
│   ├── SmartLinkModels.cs
├── Helpers/                # Utility classes
│   ├── DebugLogger.cs
│   └── UrlHelper.cs
├── lib/                    # Compiled FlexRadio libraries

Input Device Support

Serial Port (HaliKey v1):

HaliKey v1: CTS (left paddle) + DSR (right paddle)

MIDI Devices:

Supports any MIDI controller with configurable note mappings
- Tested with HaliKey MIDI and CTR2-MIDI
Note On/Off events trigger paddle/key/PTT state changes

Iambic Keyer Implementation

Software-based iambic keyer with Mode A and Mode B support
State machine is based on audio timings

Audio Sidetone

WASAPI Backend (Windows preferred):

Lowest latency

PortAudio Backend:

Cross-platform compatibility for Linux and macOS
Supports Windows DirectSound and ASIO in case WASAPI doesn’t work for some reason

Settings Persistence

User settings are stored in:

Linux: ~/.config/NetKeyer/settings.json
Windows: %APPDATA%\NetKeyer\settings.json
macOS: ~/Library/Application Support/NetKeyer/settings.json

Stored settings include:

Selected radio (serial number and GUI client station)
Input device type and selection
MIDI note mappings
SmartLink credentials (encrypted)