WSJT-X

POTACAT listens for WSJT-X UDP messages (default port 2237) and cross-references decoded callsigns against active POTA spots.

Note: You don’t need WSJT-X to work FT8 in POTACAT — JTCAT is POTACAT’s built-in FT8/FT4 engine. This page is for operators who prefer to run the separate WSJT-X application and have POTACAT work alongside it. If you’re using JTCAT, leave the WSJT-X mode checkbox unchecked.

Features:

POTA activators in the WSJT-X decode list are highlighted green
Decode indicators appear on matching rows in the POTACAT spot table
Click-to-tune sends the frequency to your FlexRadio via SmartSDR TCP (no CAT conflict with WSJT-X)
Auto-log: QSOs completed in WSJT-X can be automatically logged in POTACAT and forwarded to your external logbooks

Enable WSJT-X in Settings → Spot Sources. Set the UDP port to match your WSJT-X configuration.

Who Controls the Radio?

Two applications can’t both run CAT control of the same radio. If WSJT-X and POTACAT need the same rig, you have two options.

Option A — WSJT-X Mode (simplest)

Check the WSJT-X mode checkbox under the CAT pill. In this mode:

POTACAT’s own CAT control is disabled. Instead of talking to the radio directly, POTACAT sends UDP packets to WSJT-X, and WSJT-X controls the rig through its own CAT connection.
Clicking a spot in POTACAT asks WSJT-X to QSY the radio.
Because POTACAT isn’t holding the serial port, there is no COM-port conflict.

Warning: While WSJT-X Mode is enabled, POTACAT features that need direct rig control — including JTCAT — are unavailable. Uncheck it when you return to normal operation. If clicking a spot suddenly “does nothing,” a leftover WSJT-X Mode checkbox is a prime suspect.

FlexRadio owners get a bonus: click-to-tune goes through the SmartSDR TCP API, which works even while WSJT-X owns CAT.

Run a networked rigctld yourself and point both applications at it:

Start rigctld (Hamlib) for your radio, e.g. on 127.0.0.1:4532.
In POTACAT, choose the rigctld Network connection type with that host and port.
In WSJT-X, set the rig to Hamlib NET rigctl with the same address.

Both apps keep full rig control, and CAT survives either application closing.

Warning: Don’t use POTACAT’s Other (Hamlib) connection type for this — it spawns its own internal rigctld, which would conflict with yours and shuts down when POTACAT exits, orphaning WSJT-X. Run a standalone rigctld instead.

UDP Port 2237 Basics

2237 is the conventional WSJT-X UDP server port. Set it in WSJT-X under File → Settings → Reporting, and make POTACAT’s port match.
POTACAT opens the port with port sharing enabled, so other listeners (GridTracker, ACLog, and friends) can share 2237 — WSJT-X broadcasts to all listeners on the port.
If another application refuses to share the port, move POTACAT to a different port and use a JTAlert-style UDP relay to feed both.

Launch Order for Logger Chains

If you chain WSJT-X → POTACAT → an external logger (N3FJP, ACLog, and similar), start the programs in that order:

WSJT-X — controls the radio and produces the UDP stream.
POTACAT — attaches to the UDP stream.
Your logger — receives forwarded QSOs from POTACAT.

When you click OK on the WSJT-X log window, POTACAT auto-logs the QSO, matches the callsign against spotted POTA activators so the park is marked worked, and forwards the QSO to your configured logbooks — see Logbook Forwarding.

Tip: Starting a logger before POTACAT can leave it holding a port POTACAT needs. If forwarding or rig control fails right after startup, close everything and relaunch in the order above.

FT4 and FT2 in ADIF Exports

POTACAT exports FT4 and FT2 QSOs as MODE=MFSK with SUBMODE=FT4 (or SUBMODE=FT2), as the ADIF specification requires — files with a plain MODE=FT4 are rejected by the POTA uploader. Keep this in mind if you hand-edit exported logs.

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