One USB Cable
Any Device

Real Spectrum — FT4222 SPI & CI-V

FT-710: 850-point FFT spectrum at ~21 fps read straight from the DSP chip over FT4222 SPI. IC-7300/MK2: CI-V 0x27 475-bin scope upsampled to 850 points. TX-aware pause keeps the scope clean while transmitting; automatic S-meter fallback when no hardware path is available.

• FT4222 SPI direct read (libft4222 + libftd2xx)
• CI-V 0x27 scope via the same USB serial link
• TX-aware pause — no more post-PTT spectrum churn

FFT Plot + Waterfall

EMA-smoothed spectrum polyline above a 120-row history waterfall. Shared Floor/Ceil controls, six colormaps, and click-to-QSY anywhere on the spectrum.

• ~30 fps S-meter fallback keeps the waterfall alive
• Click-to-QSY with drag-guard for scroll gestures
• Clear "TX — spectrum paused" indicator while transmitting

Bidirectional Opus Audio

One 48 kHz codec domain end to end: RX capture → Opus 64kbps → browser AudioWorklet; browser mic → Opus CBR → server → radio. The FT-710 backend bridges to its fixed 44.1 kHz USB-audio device boundary (960→882 per 20 ms); the IC-7300 backend uses native 48 kHz USB audio with no resample.

• 64kbps Opus — 12× smaller than raw PCM
• Zero-audio watchdog flags wedged USB audio
• Graceful PTT release — word endings preserved

Full CAT / CI-V Control

FT-710: direct serial CAT over the Enhanced COM Port at 38400 baud (frequency, modes, filters, VFO A/B, split, preamp, ATT, NR/NB/AN, compressor, tuner, gains). IC-7300/MK2: USB CI-V at 115200 8N1 (addr 0x94), with Icom mode/band/filter tables and capability-driven UI adaptation.

• No Hamlib / wfview / middleware — direct serial
• Dirty-field tracking minimises WebSocket traffic
• Read-back verification on filter width sets

Adaptive Polling

100ms→5s smart intervals, 0.25s per-query timeout ceiling, and priority preemption so PTT never waits for a poll cycle. Stale in-flight reads are discarded after user commands.

• ~296 bytes/sec total serial utilisation
• Auto-zero TX meters on RX transition
• Scope re-init after every serial reconnect

Meters & Memory Channels

Canvas S-meter (S1–S9+60dB) with dBm readout plus full TX telemetry: PWR / ALC / SWR / Id / Vd / COMP. Memory channels with one-tap recall; every UI preference persists in cookies.

• Seeded starter channels, per-user storage
• AF volume, scope options, mic gain — all remembered

Server-Side QSO Recording

Press REC in the browser and the whole QSO is written on the server: reloading the page, closing the tab or losing CAT does not stop it. RX and mic audio land on one monotonic 16 kHz timeline and encode to MP3 as they arrive, so even a server crash leaves a playable prefix on disk.

• Recordings panel — list, seekable player, download, delete
• 16 kHz mono MP3 @64 kbps (~29 MB/h), no client-side encoder
• Never auto-deleted; MRRC_RECORDINGS_MAX_SESSION_MIN only stops

ATR1000 Tuner Linkage

Optional networked ATR1000 antenna tuner: learned LC relay values follow every frequency change, and a server-side tune assist runs the full carrier-measure-keep-or-rollback sequence for you.

• Off by default — zero impact without the hardware
• Learning gated on SWR 1.0–1.8, ±5kHz nearest match

NanoVNA Antenna Bench

A NanoVNA-H on the box's USB becomes a real vector analyzer page at /Nano: the complex S11 of the antenna itself, not an inference from reflected power.

• 1–54 MHz, 401 points in about one second
• SWR, impedance, Smith chart, resonance plateaus
• Scans saved as one library file, dry/wet comparison, CSV and s1p export
• Refused while transmitting — the analyzer sits on the antenna

Built-in FT8

FT8 receive and transmit inside the same server — decoding runs in its own worker process, so an SSB contact and a weak-signal slot can share the radio.

• WSJT-X Improved DSP with a fast path plus an adaptive deep-path cascade
• Waterfall, candidate list, QSO sequencing, CQ loop and a local log
• Native library built for each platform (Linux images, macOS, Windows)

SDR Receiver (box only)

An SDRplay RSP1 on the box becomes a public web receiver at /sdr: 10 kHz – 2 GHz, its own password and page, in no way coupled to radio control.

• AM / USB / LSB / CW / NFM / WFM, shared demodulators by (offset, mode, bandwidth)
• 30 s tuning hold keeps the last band choice; 50 listeners by default
• Keeps receiving while you transmit

Bluetooth Remote (box only)

The box pairs a Bluetooth HID remote and drives the radio directly — no browser, no login: the operator stands next to the antenna and tunes with the handset.

• PTT, tune, memory step and kHz entry straight from the keys
• Permission is the socket (0600, same user) — a physical button never goes through the web login
• Every release path sends ptt:false; the power key is ignored on purpose

Remote help session

When something needs a second pair of eyes, the box can open a timed SSH window to us — nothing permanent, nothing open until you ask for it.

• One-time password shown in your panel, valid only while the window is open
• Read-only awareness: it closes itself after 5 failed attempts or when you stop it
• Anonymous redacted diagnostics bundle travels the other way

Report a problem & get an answer

The menu's 🐞 Report a problem builds a redacted diagnostics bundle on the server — logs, config snapshot, radio/audio state and an auto-triage summary — and uploads it to this project's own receiver, or saves it locally when there is no uplink. Conclusions are published on the answers page, searchable by bundle id or keyword; the engineering loop behind them — bug / feature / noise classification, scheduling and unattended fixes — is on the FDE board.

• Never contains passwords, keys, tokens, recordings or memory channels
• Packaged builds now keep a rotating server log — reports became diagnosable
• An autopilot maps the evidence onto real code before answering

Multi-Layer PTT Safety

Touch-and-hold TX with instant release on touch-end. Fire-and-forget TX0 with 500ms TX-status poll + browser watchdog. Server-side forced RX when the last client — or the TX-audio owner — disconnects.

• 7 independent release layers — no single point of failure
• TX uplink ownership follows the keying client
• Graceful TX audio drain before RF drop

Mobile-First UI

Optimised for iPhone Safari: safe-area adaptation, PWA manifest with Service Worker offline caching, Wake Lock, fullscreen toggle, and native iOS / Android companion apps.

• PWA manifest + Service Worker offline cache
• Wake Lock API (screen stays on)
• Native iOS 17+ and Android apps share the same protocol

Zero inbound

The box only dials out, never opens a port. Your router does not have to change. Home broadband, 4G/5G, an office network: the same.

One call sign, one door

<call>.mrrc.vlsc.net is the entry point. The call sign is both the tenant and the account — there is no second username to maintain.

PTT stays local

The hub carries traffic and never keys the radio. When the link dies, the machine beside the radio puts it back on receive — not a timer in the cloud.

Verified hop by hop

A real certificate from browser to hub, and the hub checks yours by name. No hop is paid for by switching verification off.

Full Radio Control

Frequency (direct entry / step / band jump), VFO A/B, mode, filter width, Preamp/ATT, AGC, NB/NR/ANotch, RF power, mic gain, squelch — all from the iPhone.

• 4 encrypted WebSocket channels (wss)
• Token auth, password in Keychain

Waterfall + Meters

850-bin real-time waterfall with FFT curve, colormap matched to the web UI. S-meter plus TX meters (PWR / SWR / ALC / COMP) and memory channel list.

• Same binary spectrum frames as the browser
• Dark amber theme, portrait + landscape

Opus Voice RX/TX

RX: Opus 48kHz decode and playback through the device speaker. TX: mic capture at 48kHz in 20 ms PCM frames — hold PTT to talk.

• libopus device build (arm64)
• Settings: reconnect, gain, volume

Android Client — FT710Android

Kotlin + Jetpack Compose (Material3, minSdk 26) app speaking the same protocol: full control, waterfall + meters, Opus RX/TX, memory channels, and DataStore settings.

• PTT state machine designed-in from day one
• JVM-tested protocol & PTT logic — device RF acceptance pending

Download APK v1.1.32 (Android 8.0+)

MRRC-Modern-v1.1.32-Android.apk · 9.0 MB · SHA-256 dbd3a49ee752e731351bf7b0e6c065cb82af41ccd4b1c41cfbeb4e6066c1f65e
Install: allow “install unknown apps”, then open the APK.
⚠ This build uses a new signing key: uninstall the previously installed app first (its server settings and login will be cleared).