FT8 and FT4 — Beginner's Guide
FT8 (Franke-Taylor design, 8-FSK modulation) is the most popular digital mode in amateur radio today. Developed by Joe Taylor K1JT and Steve Franke K9AN and released in 2017, FT8 uses sophisticated signal processing to decode contacts 15–20 dB below the noise floor — signals completely inaudible to human ears. The result is a mode that lets a modest station with a simple antenna work DX that would be impossible on phone or CW. FT4 is a faster variant designed for contest use.
The 15-second sequence
FT8 operates on a strict 15-second timing cycle synchronised to UTC. During the first 15 seconds of each 30-second period one station transmits, and during the second 15 seconds the other responds. Every transmission is exactly 12.6 seconds of audio followed by a brief silence. The software encodes your callsign, the other station's callsign, their grid square, and a signal report into a highly compressed 77-bit message that fits within the 15-second window.
Because every station is synchronised to the same clock, WSJT-X can coherently decode signals from dozens of stations simultaneously on a single 3 kHz slice of spectrum. A waterfall display shows all the FT8 signals as coloured traces, and the software decodes them all automatically.
The standard FT8 exchange
A complete FT8 QSO takes about 90 seconds and consists of four 15-second transmissions. Station A calls CQ with their callsign and grid square. Station B responds with A's callsign, their own callsign, and a signal report in dB (e.g., -12 means 12 dB below noise). Station A confirms receipt and sends their signal report back. Station B sends RR73 (roger roger, 73) to confirm and end the contact. Station A may optionally send 73 to close. The entire exchange is automated by the software — you click on a decoded signal and WSJT-X handles the rest.
Download and install WSJT-X
WSJT-X is the free software that handles FT8 (and FT4, JT65, WSPR, and other weak-signal modes). Download it from physics.princeton.edu/pulsar/k1jt/wsjtx.html. Install it and run the setup wizard. You will need to enter your callsign and your Maidenhead grid square locator — find your grid square at qthlocator.50megs.com or using any online grid square calculator.
Connect your radio
WSJT-X needs to receive and transmit audio through your radio, and ideally control the radio via CAT. If your radio has USB audio (IC-7300, IC-705, FT-991A, TS-890S), connect via USB and configure WSJT-X to use the radio's USB audio device for both input and output. If your radio does not have USB audio, use a sound card interface like a SignaLink USB connected between your radio's audio jacks and your computer.
Synchronise your computer clock
FT8 timing is critical — if your computer clock is off by more than about 1 second, you will not decode signals or be decoded yourself. Windows users should enable internet time synchronisation or install Meinberg NTP. On Mac and Linux, NTP synchronisation is typically enabled by default. Use time.is to verify your clock accuracy before operating.
Set audio levels
Set your receive audio level so that the noise floor in the WSJT-X waterfall is visible but not clipping. For transmit, set your radio's audio drive so that the ALC meter barely moves — FT8 is very sensitive to overdrive. Running too much power or audio drive causes splatter that interferes with other stations. 25–50W is typically more than adequate for FT8 on HF.
Make your first FT8 contact
Tune to 14.074 MHz USB (20m FT8 frequency). Watch the waterfall fill with signals. Double-click any decoded CQ call in the decoded messages panel — WSJT-X will automatically respond and complete the exchange if the other station replies. Enable "Log QSO automatically" so contacts are logged without manual intervention. Upload to LoTW and PSK Reporter afterwards.
| Band | FT8 Frequency | FT4 Frequency | Notes |
|---|---|---|---|
| 160m | 1.840 MHz | 1.844 MHz | Night only — regional and DX |
| 80m | 3.573 MHz | 3.575 MHz | Night — regional and DX |
| 40m | 7.074 MHz | 7.047 MHz | Day and night — very active |
| 30m | 10.136 MHz | 10.140 MHz | No phone, CW/digital only |
| 20m | 14.074 MHz | 14.080 MHz | Most active FT8 band — worldwide |
| 17m | 18.100 MHz | 18.104 MHz | No phone, CW/digital only |
| 15m | 21.074 MHz | 21.140 MHz | Good DX when open |
| 10m | 28.074 MHz | 28.180 MHz | Spectacular when open at solar max |
| 6m | 50.313 MHz | 50.318 MHz | Essential for Es and meteor scatter |
Is FT8 really a proper QSO?
This is genuinely debated in the ham radio community. A completed FT8 exchange meets the FCC's definition of a two-way communication and is accepted for all ARRL awards including DXCC. Critics argue that the fully automated exchange lacks the personal interaction of a voice or CW contact. Proponents point out that FT8 enables contacts that are simply impossible by any other mode for operators with modest stations. Both perspectives are valid — FT8 is a tool, not a replacement for all other operating.
What is the difference between FT8 and FT4?
FT4 uses 7.5-second transmission periods instead of FT8's 15-second periods, making it twice as fast. FT4 was specifically designed for contest use where high contact rates are the goal. FT4 requires slightly better signal conditions than FT8 — it is not as sensitive. For casual DX operating, FT8 is the standard. For contest digital operating, FT4 is increasingly common.
What is PSK Reporter?
PSK Reporter (pskreporter.info) is a crowdsourced propagation reporting website that collects spots from WSJT-X and other digital mode software automatically. When you run WSJT-X, it uploads spots of stations you decode to PSK Reporter. The website shows a real-time map of who is hearing whom around the world. It is an excellent tool for checking band conditions and verifying that your signal is getting out.
How much power should I run on FT8?
FT8 is designed for weak-signal contacts — running high power is unnecessary and causes splatter that degrades other operators' decodes. Most successful FT8 operators run 25–100W. Running full legal limit (1500W) on FT8 is poor practice. Set your power so your ALC meter barely deflects, and let the mode's efficiency do the work.