Operating FT8

FT8 is a relatively new mode created by Pulsar Astronomer, Joe Taylor, K1JT. It encodes short defined messages in 15 second transmission cycles in 8 bit FSK, occupying a bandwidth of 50Hz so many QSOs can take place in a 2.5kHz SSB bandwidth. The entire QSO is automated with the software ensuring the correct responses are sent.

The main software used for FT8 is WSJT-X. This is available from Joe Taylors website. That site includes windows downloads and a user guide. Another option is JTDX available from https://jtdx.tech/en/. There is no noticeably performance difference between the two so which you choose is really down to personal preference.

A typical QSO on a busy band might look like this:

Here’s a breakdown of what’s happening:

  • EI6KO calls CQ giving their grid.
  • F4DIA replies with their grid.
  • EI6KO replies with a signal report
  • We didn;t get a reply so we send that message again.
  • We get his reply with a signal report.
  • We also get a reply from IK4LZH wanting a QSO. But let’s continue with F4DIA.
  • We send RR73 to F4DIA.
  • We get another call from IK4LZH.
  • We get 73 from F4DIA and we log the contact. We can now click on IK4LZH and work that station.

Advice for working FT8

  • Use the waterfall to find an empty spot to transmit then click on ‘Hold TX frequency’ so that you always transmit on that frequency. The software will scan the whole bandpass for messages – you don’t need to transmit on the same frequency as the other station.
  • Ensure your computer clock is accurate using something like Dimension 4. You can check your computer clock by visiting time.is.
  • Ensure you always reply to a CQ including your grid square for the contest.