One app from antenna to award — FT8/FT4 digital, CW, and SSB phone in a single modern operations center.

_{Offline installer — bundles WebView2 and Hamlib, per-user install, no admin rights. · Operator manual · Comprehensive overview}

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Nexus is a free, GPLv3, all-mode amateur radio operations center for the desktop. It puts a WSJT-X-parity FT8/FT4 cockpit, a CW keying station with an AI decoder (DeepCW model by e04), an SSB phone cockpit with a voice keyer, a live propagation map, an evidence-backed "work this now" board, a POTA/SOTA hunter, a club-ready Field Day mode, and a DXCC-first logbook with LoTW / QRZ / ClubLog / eQSL connectors — in one window, on one rig, with one log.

It is built in Rust (DSP, sequencing, CAT, networking) behind a Tauri desktop shell, and it treats WSJT-X as the golden standard for FT8/FT4 behavior: the auto-sequencer state machine, decode cadence, split handling, Hound mode, and the UDP ecosystem protocol all match stock — your WSJT-X muscle memory just works, inside a UI built this decade.

Why Nexus

• 🎛️ All-mode, one app. Digital, CW, and phone cockpits share one rig, one CAT layer, one logbook, and one needs engine. Entering a cockpit sets the rig up for it automatically — DATA submode for digital, CW for the keyer, the correct sideband by band for phone. No mode fumbling, no app-switching, no five stitched programs.
• 📡 WSJT-X operational parity in a modern shell. The FT8/FT4 core replicates the stock behavior the whole ecosystem depends on: the QSO sequencer state table, the early decode pass at 11.8 s, Split Operation (Rig / Fake It), Hound mode, directed CQ, the Tx1–Tx6 panel, the F-key shortcuts, and the full WSJT-X UDP protocol — JTAlert, GridTracker, and loggers see Nexus as a WSJT-X. A Classic ↔ Roster toggle gives you the stock layout or a modern sortable call roster.
• 🧭 An honest "work this now" board. Every Needed row shows its evidence — “heard by K9LC (EN52, 26 km), 4 min ago” — and admission is gated by corroboration rules: multiple receivers near you, Es-patch locality on VHF, reciprocal-path checks. A superstation on a mountain can't tell you a band is open when it isn't open at your QTH. One click QSYs the rig, opens the right cockpit, and prefills the log — split offsets parsed from cluster comments included.
• 🏞️ POTA & SOTA hunting built in. Live activator spots with NEW PARK and BAND OPEN badges, and a one-click HUNT that tunes the radio and pre-tags your next QSO with the park or summit reference in standard ADIF. Hunter-focused, zero bookkeeping.
• 🏕️ Field Day that runs the club. ARRL FD and Winter FD event modes with correct scoring (per-mode points, dupes per band per mode, legal power tiers, live bonus checklist), submittable Cabrillo 3.0 — and every contact pushed in real time to the club's N3FJP master log over its official TCP API and broadcast as native N1MM+ <contactinfo> datagrams. One laptop logs digital, CW, and phone into one dupe-checked event log.
• 🏆 A logbook that chases awards properly. DXCC, DXCC Challenge, Honor Roll, WAS, and WAZ computed offline from your log, with source-aware confirmations (eQSL never silently counts toward LoTW-grade awards), two-pull incremental LoTW sync, a per-QSO upload state machine that survives restarts, callbook autofill, and a local-only Journey achievement layer that makes the first 100 QSOs as motivating as the last 10 entities.
• 🗺️ Propagation you can act on. A live world map (3-D globe / azimuthal beam map / flat) fused from PSK Reporter, RBN/DX-cluster, and NOAA space weather; an opening detector anchored to your QTH with reciprocity gates and propagation-mode classification (Es / F2 / aurora / tropo); and a persistent Now-Bar answering “am I getting out?” from anywhere in the app.
• 🔌 Zero-config setup. Plug in the radio and click Detect my radio — Nexus reads the USB descriptors, matches the rig model, pairs the audio CODEC, and links the one driver you need if it's missing. Hamlib ships inside the installer. A goal-driven first-run wizard (“what do you want to do?”) shapes the app to you, and your declared license class becomes a real Part 97 transmit lockout — Nexus refuses to key outside your privileges, a software guard in every TX path.
• 💬 Novel weak-signal chat tiers. The original Tempo layer: TempoFast (4-second conversational cycle) and TempoDeep (fading-resilient non-coherent 8-FSK) with IR-HARQ retransmission combining and presence-gated store-and-forward — simulation-validated, seeking on-air reports.
• 🔌 Program your radios. The Program section turns "load the local repeaters into my HT" from an evening with legacy per-radio software into minutes: pick a location (your grid, any grid, or a city for a trip), fetch the repeaters around it, ADD the ones you want, and export a CHIRP-ready CSV (CHIRP flashes ~1,000 radio models) or a plain CSV — offsets, tones, channel numbers, and radio-length names handled for you. With a CAT rig connected, one click tunes the rig to a repeater now, exact odd-split offsets included. Data courtesy of RepeaterBook.com (with your own API token) or the open hearham.com directory.

Who it's for

The new ham. Nexus compresses the painful first month into an afternoon: auto rig detection instead of driver archaeology, a wizard that asks what you want to do rather than what you know, a license-class lockout so you can't transmit out of segment, an auto-sequencer that completes FT8 QSOs while you learn the flow by watching, a Needed board that says who to work and why, and a Journey layer that celebrates your firsts. You can be making contacts the day your callsign hits the FCC database.

The WSJT-X operator. Same gestures, same flow: double-click semantics straight from processMessage, Esc / F4 / F6 / Alt+1–6, Band Activity bottom-pinned in chronological order, early decodes at 11.8 s, Fake-It split keeping TX audio in 1500–2000 Hz, Hound auto-move on the Fox's report. Plus what stock never had: country and need annotations on every decode row, a sortable roster view, in-app LoTW/QRZ sync, and always-on decode (no accidental deaf Monitor-off).

The DX chaser. ATNO / new-band / new-mode / new-zone ranking across all bands simultaneously (not just the one you're tuned to), DXpedition tracking with workable-now cards, cluster split comments (“UP 2”) parsed and applied to the rig at click time, Honor Roll math, and confirmation diagnostics that explain exactly why a QSO isn't credited yet — with a one-click fix where one exists.

The club. Field Day mode reshapes the app for the event weekend and feeds club infrastructure natively — no JTAlert bridge, no end-of-day log merges. Plus a built-in CAT broker so other shack software can share the radio through Nexus.

Works with your shack

Integration	What it does
WSJT-X UDP protocol	Full outbound Decode / Status / QsoLogged / Heartbeat + inbound HaltTx, Clear, Replay, Location, Highlight — JTAlert and GridTracker see a WSJT-X
CAT broker	Nexus serves a rigctld-compatible TCP port so WSJT-X, N1MM+, and loggers share the radio through it
Companion mode	Ride an upstream WSJT-X/JTDX decode stream over UDP instead of owning the rig
N3FJP	Real-time Field Day QSO push over the official TCP API, with a connection Test button
N1MM+	Native <contactinfo> UDP broadcast per contact
LoTW	TQSL upload + two-pull incremental confirmation sync
QRZ.com	Callbook autofill, logbook push, connection test
ClubLog / eQSL	Real-time push (official installers bundle the ClubLog API key; source builds supply their own free key) / InBox confirmation import
DX cluster / RBN	Telnet feed with locality-gated VHF admission
PSK Reporter	MQTT firehose in for propagation; standard UDP spot uploads out (you appear on the map)

Credentials for every service live only in the OS keychain — never in config files, never in logs, never shown back to the UI beyond “configured.”

Quick start

1. Download the Windows installer — offline, bundles WebView2 and Hamlib, per-user, no admin needed.
2. Plug in the radio, open Settings ▸ Rig & Audio, click Detect my radio.
3. Answer the first-run wizard: callsign, grid, license class, and what you want to do.
4. Watch decodes arrive. Double-click a station — the sequencer runs the QSO, and the contact lands in the logbook, on PSK Reporter, and (if configured) on QRZ and LoTW.

New here? Start with Getting Started.

The installer is unsigned (cross-compiled on Linux), so SmartScreen may warn — More info → Run anyway. Verify the download against the SHA-256 on the download page.

Status — the honest version

• The FT8/FT4 tier is the production core: operational parity with stock WSJT-X, verified against a 207-row behavior matrix and exercised on the air daily.
• CW and Phone cockpits are casual/ragchew-grade by design: macros, voice keyer, scope, full logging — macros, voice keyer, live single-signal CW decoder, WinKeyer support, full logging — no contest exchanges yet.
• The TempoFast/TempoDeep chat tiers are simulation-validated, not yet proven on the air — AWGN and fading sweeps say they work; on-air decode-rate reports are the remaining gate and the single most useful contribution you can make.
• Windows installer is the supported package today; the codebase is cross-platform Rust/Tauri and builds on Linux.
• Not implemented (yet): Fox role (running a DXpedition end), contest modes (NA VHF / RTTY RU / WW Digi), WSPR-as-a-mode, Q65/MSK144. (Shipped since earlier revisions of this list: rotator control with satellite auto-track, the amateur-satellite section, 23 cm band support, per-QSO WAV save, HRDLog.net, a headphone monitor, and a native ITU-R P.533 propagation engine selectable beside the heuristic model.)

Architecture

┌────────────────────────────────────────────────────────────────┐
│ Tauri v2 desktop shell (src-tauri) + web UI (ui/, React + TS)  │
│   cockpits: Operate · CW · Phone · Field Day · Connect map     │
│   boards: Needed · POTA/SOTA · Logbook · Awards · Journey      │
├────────────────────────────────────────────────────────────────┤
│ Rust core (crates/)                                            │
│   tempo-app    live TX/RX engine · settings · DTOs             │
│   tempo-core   slot timing · 77-bit messages · QSO sequencer · │
│                logbook/ADIF · Field Day · reconcile            │
│   tempo-audio  cpal audio · rigctld CAT · CW keyer · voice     │
│                keyer · decode scheduler · CAT broker           │
│   tempo-net    WSJT-X UDP · PSK Reporter · DX cluster ·        │
│                LoTW/QRZ/ClubLog/eQSL · N3FJP · N1MM            │
│   propagation  needs engine · opening detector · space wx ·    │
│                awards · Journey                                │
│   tempofast/tempofast-sys  safe wrapper + FFI over libtempo                  │
├────────────────────────────────────────────────────────────────┤
│ libtempo (Fortran → C ABI, FFTW3, no Qt)                         │
│   FT8/FT4 encode+decode · TempoFast 4-CPM turbo + IR-HARQ ·          │
│   TempoDeep non-coherent 8-FSK + soft LDPC                           │
└────────────────────────────────────────────────────────────────┘

See docs/ARCHITECTURE.md for the full design.

Building from source

git clone https://git.code.sf.net/p/nexus-ham-radio/code nexus
cd nexus
cargo test --workspace                  # Rust core (modem FFI, engine, sequencer, exports)
cd ui && npm install && npx vitest run  # UI suites
# Windows installer, cross-compiled from Linux/WSL2:
./scripts/build-windows-cross.sh

The TempoFast/FT8 modem is Fortran + C behind a Rust FFI, so the GNU toolchain is required — see Building from Source and WINDOWS.md.

Documentation

• Comprehensive overview — every surface, in depth
• Operator manual — setup, per-mode operating guides, integrations, troubleshooting
• TempoFast protocol specification — the native waveform, for implementers
• Frequency plan — where the TempoFast/TempoDeep tiers live on the bands

License & credits

Nexus is free software under the GNU GPL v3 (GPL-3.0-only).

• WSJT-X — Joe Taylor K1JT, Steve Franke K9AN, Bill Somerville G4WJS, and the WSJT Development Group. Nexus's digital modem (libtempo/) is derived from WSJT-X: the FT8/FT4 codec, the 77-bit message packing, the LDPC(174,91) FEC, and the CRC-14 check are their GPL-licensed work, vendored and reused unmodified via a foreign-function interface (see NOTICE for the full lineage and marked modifications). Nexus interoperates with their ecosystem over the standard WSJT-X UDP protocol; its auto-sequencer is original Rust modeled on WSJT-X's on-air behavior. Nexus is not endorsed by nor affiliated with the WSJT Development Group. GPLv3.
• TempoFast / TempoDeep — the native weak-signal waveforms by KD9TAW.
• AetherSDR (GPLv3) — the waterfall's 3D stacked-spectrum view (ui/src/dss.ts) and retained-history model (ui/src/waterfallHistory.ts) are ported from AetherSDR's DssRenderer / WaterfallHistoryBuffer; its PanadapterStream was a wire-format reference for the native Flex DAX/VITA path (see NOTICE).
• Hamlib — bundled rigctld for CAT control (GPL/LGPL).
• FFTW (GPL), Tauri, React, cpal, Natural Earth basemap (public domain).

This is experimental amateur-radio software. You are responsible for operating within your license privileges and local regulations. Nexus never transmits on launch; ARRL Field Day prohibits fully-automated contacts, and Nexus's Field Day workflow is operator-initiated by design.

Author: KD9TAW · kd9taw@protonmail.com · contributions welcome — see CONTRIBUTING.md and the Code of Conduct.

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