AetherSDR

A Linux-native client for FlexRadio Systems transceivers

AetherSDR brings FlexRadio operation to Linux without Wine or virtual machines. Built from the ground up with Qt6 and C++20, it speaks the SmartSDR protocol natively and aims to replicate the full SmartSDR experience.

Current version: 0.7.17.2 | Download | Discussions

Cross-platform downloads available: Linux AppImage, macOS universal DMG, Windows installer (.exe) and portable ZIP. Linux is the primary supported platform. macOS and Windows builds are provided as a courtesy but are unsupported and low priority until post-v1.0.

Native. Open. Yours.

Supported Radios

Tested with the FLEX-8600 running v4.1.5 software. Should work with other FlexRadio models that use the SmartSDR protocol (FLEX-6000 series, FLEX-8000 series).

Features

Multi-Slice Operation

Color-coded slice markers on spectrum and waterfall (A=cyan, B=magenta, C=green, D=yellow)
Click inactive slice badge to switch focus
Independent TX assignment — TX stays on its slice until explicitly moved
Clickable TX badge in VFO overlay (red = active TX, grey = click to assign)
Close (✕) and lock (🔒) buttons floating beside the VFO overlay
+RX button creates new slices on the current panadapter
Right-click context menu to close slices
Off-screen slice indicators with frequency display
Diversity mode (DIV) — dual-SCU diversity reception with ESC beamforming
ESC controls — polar display, phase/gain sliders, real-time ESC signal meter

Panadapter & Waterfall

Real-time FFT spectrum and scrolling waterfall display
Draggable FFT/waterfall split, bandwidth zoom, pan
Draggable filter passband edges
dBm scale with drag-to-adjust, time scale on waterfall
ARRL band plan overlay on FFT display (color-coded CW/DATA/PHONE segments with license classes)
Spot frequency markers with hover tooltips (QRP calling, beacons, SSTV, etc.)
SpotHub — unified spot manager (Settings → SpotHub) with DX Cluster, RBN, WSJT-X, POTA, and FreeDV sources, sortable spot list with band filters, density badges, per-source color coding, and configurable lifetimes
FreeDV Reporter — real-time FreeDV station spots via Socket.IO WebSocket to qso.freedv.org
Floating VFO widget with S-meter, frequency, and quick controls
Band selector with ARRL band plan defaults
Display sub-menu: AVG, FPS, FFT fill (opacity + color), weighted average
Waterfall controls: gain, black level (+ auto), scroll rate
Native VITA-49 waterfall tiles with automatic FFT fallback during TX
FFT and waterfall rendering fully decoupled
All overlays consume mouse/wheel events (no accidental VFO tuning)
Band zoom buttons (S/B) — quick zoom to phone segment or full band

Receiver Controls

Full RX controls: antenna, filter presets, AGC, AF gain, pan, squelch
All DSP modes: NB, NR, NR2 (spectral), ANF, NRL, NRS, RNN, RN2 (RNNoise), NRF, ANFL, ANFT, APF
NR2 spectral noise reduction — Ephraim-Malah MMSE-LSA with OSMS floor tracking (contributed by @EI6JGB)
RN2 neural noise suppression — Mozilla/Xiph RNNoise deep-learning denoiser, bundled (no external dependency)
BNR GPU noise removal — NVIDIA Maxine neural denoiser via self-hosted Docker container (RTX 4000+), real-time gRPC streaming with intensity control
FFTW3 optimized FFTs with automatic radix-2 fallback and background wisdom generation
DSP level sliders (0-100) for all supported features
CW decoder — real-time Morse decode using ggmorse, auto-detects pitch and speed, confidence-colored text (green/yellow/orange/red)
Mode-specific controls (CW pitch-centered filters, RTTY mark/shift, DIG offset, FM duplex)
RIT / XIT with step buttons
Per-mode filter presets and tuning step sizes
Dynamic mode list from radio (supports FDVU, FDVM, and future modes)

Transmit Controls

TX power and tune power sliders
TX/mic profile management
TUNE, MOX, ATU, and MEM buttons
ATU status indicators and APD control
P/CW applet: mic level/compression gauges, mic source selector, processor, monitor
PC audio TX via DAX stream — auto-starts when mic source = PC
Mic metering with RX monitoring (met_in_rx)
PHONE applet: VOX, AM carrier, TX filter
8-band graphic equalizer (RX and TX)
Volume boost up to +6 dB (200%) with software gain

DAX Virtual Audio (Digital Mode Integration)

4 RX virtual capture devices + 1 TX virtual sink for WSJT-X, VARA, fldigi, JS8Call
Linux: PulseAudio/PipeWire pipe modules (works with both)
macOS: CoreAudio HAL plugin with shared memory
Per-channel gain sliders with real-time level meters (MeterSlider widget)
DAX TX audio routing: mode-aware gating (voice/digital/RADE)
Autostart DAX on connect with persistent settings

Metering

Analog S-Meter gauge with peak hold
TX power, SWR, mic level, and compression gauges
4o3a Tuner Genius XL (TGXL) applet with relay bars and autotune

FM Duplex

CTCSS tone encode (41 standard tones)
Repeater offset with simplex/up/down direction
REV (reverse) toggle

Tracking Notch Filters (TNF)

Right-click spectrum or waterfall to add TNF at any frequency
+TNF button creates a notch at the center of the filter passband
Drag TNF markers to reposition
Right-click TNF to adjust width (50/100/200/500 Hz) and depth (Normal/Deep/Very Deep)
Permanent TNFs (green) survive radio power cycles; temporary (yellow) are session-only
TNF markers render across both spectrum and waterfall with grab handles
Global TNF enable/disable synced with radio

CAT Control & Integration

4-channel Hamlib rigctld TCP server (ports 4532-4535), one per slice (A-D)
Virtual serial ports (PTY) at /tmp/AetherSDR-CAT-A through -D
PTT auto TX-switch: keying a channel moves TX to that channel's slice
Autostart options for rigctld and TTY
Supports: get/set frequency, get/set mode, PTT, split, dump_state

Digital Voice (RADE)

FreeDV RADE (Radio Autoencoder) — AI-based digital voice codec (contributed by @pepefrog1234)
Client-side neural encoder/decoder — radio does SSB passthrough (DIGU/DIGL)
TX: mic → LPCNet feature extraction → RADE OFDM modulation → radio
RX: DAX audio → RADE demodulation → FARGAN neural vocoder → speaker
Bundled with Opus (auto-downloaded at build time) — no separate installation
Available on Linux and macOS; Windows support tracked in #87

SmartLink Remote Operation

Log in with FlexRadio SmartSDR+ account (email/password via Auth0)
Radio auto-discovered via SmartLink relay server
Full TCP command channel over TLS — tune, change modes, all controls work remotely
VITA-49 UDP streaming over WAN — FFT spectrum, waterfall, RX audio, and meters
WAN UDP registration via client udp_register protocol (matching FlexLib)
NAT pinhole keepalive (5-second UDP ping) for sustained remote sessions
Requires UPnP or port forwarding on the radio's network

Connectivity

Auto-discovery of radios on the local network (UDP broadcast)
Manual connection for routed networks (cross-subnet, VLANs)
Saved routed radios auto-probe and reconnect on launch
SmartLink for internet remote access
Auto-reconnect on connection loss
Auto-connect to last used radio on launch

Audio

Radio audio outputs: line out gain/mute, headphone gain/mute, front speaker mute
PC audio input/output device selection with live switching
Full settings in Radio Setup → Audio tab

USB Cable Management

Configure USB-serial adapters plugged into the radio's rear USB ports
CAT cable: serial parameters, frequency source, auto-report
BCD cable: band decoder with polarity and HF/VHF selection
Bit cable: 8 independent bits with band/frequency/PTT/delay per bit
Passthrough cable: raw serial tunnel with configurable serial parameters

MIDI Controller Mapping

Map any class-compliant USB MIDI controller to 50+ AetherSDR parameters
MIDI Learn — select a parameter, move a knob, binding created automatically
Supports CC (knobs/faders), Note On/Off (buttons/pads), and Pitch Bend
Dedicated Settings → MIDI Mapping dialog with device selector and binding table
Real-time activity indicator showing incoming MIDI messages
Named profiles for different controllers (save/load)
Parameters: AF gain, squelch, RF power, MOX, TUNE, mic level, EQ bands, and more
Bindings persisted in dedicated midi.settings XML file
Optional dependency (RtMidi) — feature hidden when not available

Radio Setup

Full settings dialog (10 tabs): Radio, Network, GPS, Audio, TX, Phone/CW, RX, Filters, XVTR, USB Cables
Per-band TX settings: RF power, tune power, PTT inhibit, interlock routing
TX profile management
XVTR transverter configuration
Firmware update — upload .ssdr files directly from Linux (no Windows required)
Network diagnostics, memory channels, spot settings

External Control

FlexControl USB tuning knob — auto-detect, rotary tuning with acceleration, 3 configurable buttons
MIDI controllers — knobs, faders, and buttons mapped to radio parameters with Learn mode
Serial PTT/CW keying — USB-serial DTR/RTS output for PTT and CW key, CTS/DSR input for foot switch/paddle

General

Click-to-tune and scroll-wheel tuning on spectrum
Right-click context menu on spectrum and waterfall
Persistent display settings: WNB, RF gain, black level saved across sessions
Multi-Flex support (independent operation alongside SmartSDR/Maestro)
XML settings persistence (SSDR-compatible format)
Persistent window layout and display preferences
Cross-platform: Linux (primary), macOS, Windows
Desktop integration (.desktop file, icon, cmake --install, AUR package)
PC audio TX via DAX stream (mic TX also supported)
Security hardened: redacted logs, restricted file permissions

Download

Pre-built binaries are available from Releases:

Platform	Download	Notes
Linux x86_64	`AetherSDR-*-x86_64.AppImage`	Single file, no install needed. `chmod +x` and run.
Linux ARM	`AetherSDR-*-aarch64.AppImage`	Raspberry Pi, ARM laptops. `chmod +x` and run.
macOS DMG	`AetherSDR-*-macOS-universal.dmg`	Intel + Apple Silicon. Drag to Applications. Signed & notarized.
macOS Installer	`AetherSDR-*-macOS-universal.pkg`	Installer package. Signed & notarized.
Windows Installer	`AetherSDR-*-Windows-x64-setup.exe`	Setup wizard with Start Menu shortcut and uninstaller.
Windows Portable	`AetherSDR-*-Windows-x64-portable.zip`	No install needed. Extract and run.

Linux is the primary development platform and receives the most testing. macOS and Windows builds are provided as a convenience — they compile from the same codebase but are not actively tested or supported. Bug reports are welcome but fixes for macOS/Windows issues will be low priority until after v1.0.

Building from Source

Dependencies (Linux)

# Arch / CachyOS / Manjaro
sudo pacman -S qt6-base qt6-multimedia cmake ninja pkgconf autoconf automake libtool

# Ubuntu 24.04+ / Debian / Linux Mint / Elementary OS
sudo apt install qt6-base-dev qt6-multimedia-dev cmake ninja-build pkg-config \
  autoconf automake libtool gstreamer1.0-pulseaudio gstreamer1.0-plugins-base \
  libxkbcommon-dev portaudio19-dev libfftw3-dev

# Fedora
sudo dnf install qt6-qtbase-devel qt6-qtmultimedia-devel cmake ninja-build \
  autoconf automake libtool

# macOS (Homebrew)
brew install qt@6 ninja cmake pkgconf autoconf automake libtool

Linux Mint / Ubuntu note: If PC audio devices show as "Dummy Output" or empty, install the GStreamer PulseAudio plugin: sudo apt install gstreamer1.0-pulseaudio. For PipeWire-based systems (Mint 22+, Ubuntu 24.04+), also install gstreamer1.0-pipewire.

Build & Run

git clone https://github.com/ten9876/AetherSDR.git
cd AetherSDR
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build -j$(nproc)
./build/AetherSDR

The application will automatically discover FlexRadio transceivers on your local network.

Install (optional, Linux)

Install the binary, desktop entry, and icon system-wide:

sudo cmake --install build

This places AetherSDR in /usr/local/bin, the .desktop file in the app launcher, and the icon in the system icon theme.

Roadmap

Shipped

In Progress

SmartLink own Auth0 credentials (pending FlexRadio developer support)

Planned

DAX audio channels — Windows virtual audio devices (#87)
GPU-accelerated spectrum/waterfall via QRhi (#391)
Detachable/pop-out panadapter and radio panel windows (#246)
CW keyer memories and CWX macros (#18)
Master PC volume control (#137)
Headless ASAN test infrastructure (#440)

See the full issue tracker for all tracked features and enhancements.

Contributing

PRs, bug reports, and feature requests welcome! See CONTRIBUTING.md for guidelines.

Development environment: AetherSDR is developed using Claude Code as the primary development tool. The entire codebase — architecture, conventions, and patterns — is built and maintained through AI-assisted development. To ensure consistency and minimize integration issues, we strongly encourage all contributors to use Claude Code for development. PRs must follow the project's established conventions, pass CI, and integrate cleanly with the existing architecture.

Not a developer? You can still contribute great feature requests using AI. See the AI-Assisted Feature Requests section in our contributing guide — it walks you through using Claude.ai to turn your idea into a well-structured request that's easy for us to implement.

The codebase is modular — each subsystem (core protocol, models, GUI widgets) can be worked on independently. Check Issues for current tasks.

Verifying Downloads

Linux AppImages, Windows binaries, and source archives are GPG-signed. macOS artifacts are Apple notarized. Each release includes detached signatures (.asc) and a signed SHA256SUMS.txt. All commits on main are signed by their authors.

# Import the public key
curl -sSL https://raw.githubusercontent.com/ten9876/AetherSDR/main/docs/RELEASE-SIGNING-KEY.pub.asc | gpg --import

# Verify a download
gpg --verify AetherSDR-v1.0.0-x86_64.AppImage.asc AetherSDR-v1.0.0-x86_64.AppImage

See docs/VERIFYING-RELEASES.md for full instructions.

License

AetherSDR is free and open-source software licensed under the GNU General Public License v3.

AetherSDR is an independent project and is not affiliated with or endorsed by FlexRadio Systems.

KD4Z/AetherSDR

README