FT8

FT8, love it or loathe it you cannot ignore it.  FT8 has been the mode of choice for many operators on all bands from 160m upwards.  Castigated by some as simply two computers in contact, a degree of human input is nevertheless required.  This is particularly true at 6m where knowing how propagation works at these frequencies and where and when to point your beam can really affect the sort of ‘DX’ that you work.  FT8 has dominated 6m in the past 18 months; perhaps unsurprisingly when the possibilities become apparent.

So what is it?  Devised by Joe Taylor K1JT it is a weak signal mode where computer algorithms are able to dig extremely weak signals out of the background noise and recover useful information from the transmitted signal.  This is typically a call-sign, 4 digit locator square and an indication of the strength of the station being worked in dB.  Typically something between +25 (very strong) and -25 (very weak).   Additionally, the programme will send 73 and acknowledge receipt of the signal report.  This is sufficient to qualify for a valid QSO although the niceties of name QTH etc are missing.

There is absolutely no doubt that it is possible to work DX that would have been impossible via the traditional modes of SSB and CW.  The mode has distinct advantages for those unable to run the legal limit to a large array.  Even 10 Watts to a vertical or small Yagi is capable of surprising results.  This short brief is not intended to go into the detail of how to set up your station to use FT8, for that this link should tell you all you need to know:  https://www.g4ifb.com/FT8_Hinson_tips_for_HF_DXers.pdf  The link will also point you to downloads for the software itself.  Ensure that you download the latest release as earlier variants are not necessarily compatible!
 
ft8-screenshot.pngThere are three main programs, any of which will achieve the same outcome: WSJT-X, JTDX and MSHV. Which you choose is down to personal preference.  My advice would be to use one until you become familiar with it and then try the others.  They are sufficiently similar that a second learning curve will be very short.   A swift Google for FT8 will bring you a lot more information if you have the time to sift through it all. The example shown here is JTDX.
 
It will take a short while to become comfortable with the software but it is fairly intuitive and there is plenty of help available both within the software via drop down boxes and also out there on the net, especially via YouTube.

There are two main frequencies used for FT8; these are 50.313 and 50.323. 50.313 is the ‘work horse’ frequency where most of the general operation takes place, especially within your own continent. Here it is largely immaterial which transmit sequence is used as the opposite sequence is always used by your QSO partner. It would make sense though when calling CQ to use (Tx 00/30) if you are in Europe as most US and Asian stations will transmit in the odd sequence and therefore won't be heard. 

By convention, 50.323 should only be used for QSO’s outside your continent with Europe transmitting in the first sequence (Tx 00/30) and the USA/Asia transmitting second sequence (Tx 15/45)
 
DX outside these main areas are free to choose which sequence will suit them best for the area they intend to work.

FT4 is a variant of FT8 and is intended for faster QSO’s (typically around half the time taken by FT8) and is therefore much more suitable for contest operation; the trade off for this increased speed is reduced sensitivity. It uses four tones rather than the eight used by FT8 and has a recommended frequency of 50.318. At present, UKSMG do not accept contest entries for FT8/FT4 QSOs. This is largely intended to retain the cut, thrust and excitement generated by a SSB/CW contest as well as to retain a relatively even playing field.

Finally, bear in mind that there are other well used digital modes and that these have not been supplanted by FT8 although it may seem that way. For example, JT65 has a little more sensitivity than FT8 and is probably a better option over particularly marginal paths where the QSO is by prior arrangement.


EA5ISZ, Jun 2020