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First contact

The standard this project holds itself to: a licensed ham with moderate Linux experience gets from a fresh install to a working digital-modes station without asking anyone a question or reading a forum thread. This page is that last stretch — from installed software to a decode on the waterfall.

It is the short version. Two guides carry the long one: FT8 and the digital modes walks rig control, the clock, your callsign in each program, the first FT8 QSO, PSK31, RTTY and JS8Call; Radio audio covers the sound path between radio and program on PipeWire, levels and the ALC trap, and its own list of audio symptoms.

The chain you are building

A digital-modes station is four things wired together:

  1. The radio, on a band with activity (20 m and FT8 is the reliable first test — 14.074 MHz).
  2. Audio between radio and computer, both directions. A sound-card interface or a Digirig-class device. This is the part that most often needs attention: the computer must hear the radio and be able to talk back.
  3. PTT — how the software keys the radio. CAT (through hamlib/flrig), a serial line, or VOX.
  4. The software — WSJT-X for FT8, from the digital-modes profile.

Wire it up

After hammunition install station digital-modes:

  1. Check the clock. timedatectl should say System clock synchronized: yes. FT8 decodes nothing, with no error, when the clock is a second out; Time and position covers a station with no network.
  2. Set your callsign and grid if you have not: hammunition station set --callsign … --grid-square …. WSJT-X asks for them on first run too; Your callsign in each program lists where every program wants them.
  3. Rig control. Say which radio you have (hammunition station set --rig …, then hammunition install rig-service) and WSJT-X talks to it as Hamlib NET rigctl at 127.0.0.1:4532; or start flrig, select your radio and choose FLRig in WSJT-X. Either way exactly one program holds the serial port and everything else asks it, so there is no second CAT cable fight. Rig control walks both.
  4. Audio routing. In your sound settings, confirm the interface appears as both an input and an output device. In WSJT-X's Settings → Audio, select it for both. The waterfall should come alive with the band's noise. Finding which device is the radio, and keeping it from becoming the desktop's default output, is in Radio audio.
  5. PTT. WSJT-X → Settings → Radio: set PTT to CAT (through the rig service or flrig) or a serial line. Test with the Tune button — the radio should key and show output into a dummy load or antenna.

The first decode

Tune to 14.074 MHz USB, watch WSJT-X's waterfall for the FT8 signature (evenly spaced tones in fifteen-second cycles), and let it run a cycle. Decodes appear in the left pane: callsign, grid, signal report. That is first contact with the mode — you are hearing the band.

Answering a CQ is one double-click, but hearing decodes first proves the whole chain works receive-side before you transmit.

When the waterfall is silent

Symptom-first, because that is how trouble actually presents:

  • Waterfall flat, no noise → the computer is not hearing the radio. Wrong input device in WSJT-X, or audio cable in the wrong jack. Confirm the interface shows input level in your OS sound settings first; the audio symptoms list goes further.
  • Signals on the waterfall, no decodes → the clock. FT8 needs it within about a second; see the time section.
  • Decodes but Tune does not key the radio → PTT. Wrong CAT setting or serial line; first read the frequency back through the program that owns the port (rigctl -m 2 -r 127.0.0.1:4532 f, or flrig's own panel), then see Rig control.
  • dialout permission errors on the serial device → you were added to the group at install, but group membership needs a fresh login. Log out and back in.

  • On Wayland, a ham GUI misbehaves (blank window, no decorations — WSJT-X on a Pi is the classic) → switch the session to X11. This is accumulated operational knowledge, not a bug in the software.

  • Decodes appear, but only a few, and the time column looks wrong → the clock. timedatectl.

Each step above has a full guide: rig control, radio audio, and FT8 and the digital modes, which goes on to JS8Call and fldigi. Deeper symptom-first help lives in the troubleshooting section; each program's package page carries its own known problems and where to get real support for it.

Back: Your first profile. Next: the guides, one task each.