FT8 101 – An Intro

How hard could this be?

Blair Kitchen <KE2EHU> - April 2, 2025

Agenda

• What is FT8?
• How do we get on the air with FT8?
• Connecting your rig to your computer
• Configuring WSJT-X
• Operating WSJT-X and Responding to CQ

Caveats

• I’m a beginner – I only sort of know what I’m doing
• Some of this is my mental model – It’s not always 100% accurate, but it gets the job done
• I’ve done this on exactly one radio – I can’t guarantee it’s all the same in your specific setup

What is FT8?

What is FT8?

• Digital mode used for weak signal communication
• Digital mode = Computer required to encode/decode messages
• Requires only 50 Hz (0.05 kHz) of bandwidth and can be decoded at -20 dB
• SSB Phone is 3000 Hz (3.00 kHz)
• Pre-defined exchange to communicate callsign, location and signal report
• Does NOT support arbitrary messages, rag chewing, etc.

Why use FT8?

• Useful in noisy environments (it will get you on the air)
• Measuring signal propagation (https://www.pskreporter.info)
• Testing antennas
• Contesting / DXing
• Good introduction to digital modes
• Widely used and relatively simple
• Confirms your rig and PC are communicating

FT8 and Timing

• Transmission is in fixed time windows
• 15 seconds of transmit / 15 seconds of receive
• Requires both sides to have the same understanding of time
• Use NTP (Network Time Protocol) to keep your PC in sync with others

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So how do we get on the air with FT8?

Step 1 – Connect your radio to your computer

Radio – With a person

Radio

Mic

Speaker

Audio

Speech

PTT

Frequency, etc.

(Buttons and Dials)

Me

Replace all of this with a computer

Audio Out

Audio In

Radio – With a computer

Radio

Audio Out

Cat Control

(PTT, Frequency, etc)

Computer

Serial Port

WSJT-X

Audio In

WSJT-X is the “brain” controlling the radio and encoding / decoding signals

Hardware / Software

• WSJT-X (https://wsjt.sourceforge.io/wsjtx.html)
• Software for encoding / decoding FT8 digital mode
• Also provides rig control
• External Interface (Xiegu G90)
• Sound Card (Audio In / Out)
• You’ll need cables to connect your radio to your sound card
• Serial Port (Rig Control)
• You may need a serial->USB adapter
• Digirig (https://digirig.net)
• Built-in Soundcard and Serial Passthrough
• Cables built for specific radios
• Single USB connection to your computer
• Built-in Interface
• Some HF radios have built-in interfaces. Check your manual

My Setup – Xiegu G90 w/ Digirig and Macbook

Configure Radio for Digital Modes

• Some radios require manual setup
• Xiegu G90 – Make sure mode is U-D (Upper Side Band – Data) – I think this is what causes audio to be sent to Line Out

Set your Transmission Power

• Digital modes transmit at the maximum configured power
• Don’t go above 50% of your equipment's max power rating
• Ratings are typically for phone mode
• Keep an eye on equipment temperature!
• 10W probably good enough for FT8

So how do we get on the air with FT8?

Step 2 – Set up your radio and WSJT-X

WSJT-X Settings – General

• Enter your call
• Enter your grid
• Enter your IARU Region
• Check “Display distance in miles”

WSJT-X Setup – Radio

• Radio dependent – Read your manual!
• For My Setup
• Rig – Xiegu G90
• Serial Port – System dependent
• Baud Rate – 19200
• PTT Method – CAT
• Mode – Data/Pkt
• Split Operation – Fake It
• Click Test CAT – Will be red or green depending on success
• Click Test PTT – Confirm your radio goes into Tx then click again to stop

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WSJT-X Setup – Audio

• System Dependent
• For My Setup
• Input – USB Audio Device (Digirig)
• Left Channel
• Output – USB Audio Device (Digirig)
• Left Channel

WSJT-X Setup – Reporting

• Check “Prompt me to log QSO”
• Reminds you, via popup, to record a QSO when exchange is complete
• Check “Enable PSK Reporter Spotting”
• Submit your spots to https://pskreporter.info

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So how do we get on the air with FT8?

Step 3 – Operating WSJT-X

WSJT-X - Monitoring

• Select a band and WSJT-X will auto-tune your rig
• 20m = 14.074.000
• Click the “Monitor” button if it’s not already green
• Watch the signal bar on the left
• Keep it green (40-60)
• If it’s too high / low, adjust line out volume on your radio
• You should start seeing the Band Activity window populate

How am I seeing all this traffic?

• Remember FT8 requires only 50 Hz of bandwidth
• Your radio is likely set to filter 3000 Hz
• WSJT-X can filter out the various signals and decode all the traffic within that 3000 Hz window

20m

14074 kHz

14077 kHz

WSJT-X – Responding to CQ

• In the Band Activity panel, find a CQ
• These are usually colored entries
• Double-Click on the CQ to which you want to respond
• Messages in the lower right will auto-populate
• Select “Enable Tx”
• This will start the Tx/Rx cycle

What just happened?

CQ Calls are highlighted in

various colors

Your transmissions are

highlighted in yellow

Messages directed at you

are highlighted in red

I made a QSO! Where are my logs?

• WSJT-X logs QSOs in ADI format (I think by default)
• All QSOs stored in a single ADI file
• Go to File -> Open Log Directory in the menu
• Look for file wsjtx_log.adi
• Import into your logging software
• Some logging software can connect directly to WSJT-X and automatically import QSOs as they happen

What’s Next?

• Go deeper into FT8
• Call CQ!
• Set up helper programs like GridTracker (https://gridtracker.org)
• Automate your logging process
• Try other digital modes!
• You’ve done the hard part connecting your radio to your computer
• WSJT-X offers modes beyond FT8
• Other modes are also out there! JS8Call is derived from FT8 and setup is almost identical!

References

• FT8 – https://en.wikipedia.org/wiki/FT8
• Digimode Automatic Propagation Reporter – https://www.pskreporter.info
• WSJT-X - https://wsjt.sourceforge.io/wsjtx.html
• Digirig - https://digirig.net
• GridTracker - https://gridtracker.org

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