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Decoding FT4

FT4 is FT8's faster sibling, popular in contests: the same kind of short messages, in 7.5-second slots instead of 15. The console's FT4 panel lists the FT4 messages your radio hears. The RemoteMyShack agent decodes them at the shack, by the shack computer's clock, so it works on a slow connection and with your device's audio off.

FT4 is part of the Super Station plan (and the free trial) when you operate remotely. At the shack, on the shack computer's own network, it's always available. See Plans and pricing.

Open the panel

Put the radio in USB with DATA on (USB-D). A panel for digital modes opens under the mode buttons.
Click FT4 in the row of buttons above it.
Choose a band from Go to band…. It tunes to the band's usual FT4 frequency (14.080 MHz on 20m) and switches to USB-D if the radio isn't in it.

FT4 slots start every 7.5 seconds: at :00, :07.5, :15, :22.5 and so on past each minute. Messages appear about 6.5 seconds into the slot they're sent in. The progress bar shows where the current slot is.

The agent decodes only while at least one console has the FT4 panel open. When you open it, it shows the last five minutes it decoded, if anyone had it open.

Reading it

Each slot starts with its time (UTC, as hhmmss), then one line per message, by audio frequency, with the same columns as FT8's Band activity:

dB: the signal-to-noise ratio, an estimate as WSJT-X reports it.
DT: how many seconds late the signal started.
Hz: the message's audio frequency. Hover over a line to see its frequency in MHz.
The message. CQ calls are green, messages to your callsign are highlighted, and messages from it are in the accent color.

Tick CQ and me only to hide the rest. Clear empties the list in this console.

The shack computer's clock must be right to within about a second, as for FT8. Keep the radio's receive filter wide (about 3 kHz): the decoder looks for signals from 200 to 3000 Hz.

How it decodes

FT4 uses FT8's decoder, built from the published protocol and the open-source ft8_lib. Like the FT8 decoder, it misses some very weak or overlapping signals that WSJT-X finds.

Not built yet: transmitting FT4, so you can't answer a station from the panel. Use FT8 to make contacts.