Sunday, November 26, 2017

Digital Modes Are Gaining Popularity

An Introduction To FT8 Mode


Richard Jannes, PD3RFR

FT8 is a new digital mode, introduced in July 2017 and developed by K9AN (Steven Franke) and KJ1T (Joe Taylor). FT8 stands for "Franke and Taylor, 8-FSK modulate".  It’s similar to JT65, with one big difference. The transmissions duration is only 15 seconds instead of 60 seconds in JT65. This mode was developed especially for contacts where large fluctuations in signal strength occur, QSB for example. A disadvantage is that the sensitivity is 10dB less than JT65. FT8 decodes signals to-20dB.

As in all other digital modes (JT65, PSK31, SSTV etc.) you need to have an audio interface between the transceiver and the computer's sound card. For this I use the MicroHam USB Interface III. Of course you need software that supports this mode, in this case that is WSJT-X version 1.80. This software can also control your transceiver and runs on many versions of Windows (including Windows 10), and is also available for other platforms.

It is very important that your computer clock  is synchronized to the hundredth of a second with the station you are contacting, otherwise you’ll miss a piece of the transfer. For years I’ve used the synchronization of the Meinberg Network Time Protocol. Another option is NetTime, which is easier to get working by a layman.

Here is an example of a QSO as it is intended with FT8, where PA1TEST (fictitious call) responds to my CQ call:

"CQ PD3RFR JO22″ CQ call from PD3RFR (JO22 is the grid square location)
"PD3RFR PA1TEST AB12″ PA1TEST responds to the CQ with its location AB12
"PA1TEST PD3RFR-08″ PD3RFR responds with a signal report
"PD3RFR PA1TEST R-12″ PA1TEST responds (replies) with a signal report
"PA1TEST PD3RFR Rahman" PD3RFR says reception report received
"PD3RFR PA1TEST 73″ PA1TEST says ‘with best regards'
"PA1TEST PD3RFR 73″ PD3RFR says 'with best regards'

Although this passage has lasted only 7x 15 seconds, it seems to be too long for some amateurs. In actual practice, I have regularly seen the following method, in which the actual QSO only takes 60 seconds.

"CQ PD3RFR JO22″ CQ call from PD3RFR (JO22 is the Location)
"PD3RFR PA1TEST-08″ PA1TEST responds with a signal report
"PA1TEST PD3RFR R-12″ PD3RFR responds (replies) with a signal report
"PD3RFR PA1TEST Rahman" PD3RFR says reception report received
"CQ PD3RFR JO22″ PD3RFR goes on to a new general call

It’s handy to use the online PSK Reporter Tool so you can see where your FT8 signal is received with your particular transmitter and antenna setup. Then you don’t need to unnecessarily call stations that you see, but who do not hear you.

On the screenshot of the  WSJT-X program [right] I was in a QSO with an Amateur in Scotland. As with JT65, there is a ‘Waterfall’ display which shows several QSOs. After tuning to an FT8 frequency, you see the received stations every 15 seconds in the ‘Band Activity’ box . If you see an interesting station, click on a CQ message (pink lines) to respond. If you receive an answer, you will see the response in the ‘RX Frequency’ box on the frequency where you send and receive. The colours are set in the software preferences but I just left them at the default. Unlike JT65, the advantage of this software is that it goes through the whole process/QSO by itself. So just click once and the QSO is completed when your contact station responds. If you send out a CQ call, then you can have this answered automatically.

Logging a QSO to an ADIF file is easily done by the program itself. An ADIF file can be opened in settings, or the contact can be imported to another program like HRD Logbook. Of course it’s cumbersome to paste one file into another every time and then also forward it to, for example, LoTW or eQSL. Therefore it’s useful to install an extra piece of software JTAlertX [from version 2.10.1 shown below]. This program allows you to automatically forward an entry to your preferred logbook/application, for example HRD. You can also permit this program to alert you to DXCC and calls that you would like to work in your log.


FT8 is used on different shortwave bands in upper sideband mode. For the novice that is on 10 meters at 28.074 MHz, 20 meters 14.074 MHz, and 40 meters 7.074 MHz.


Because radio amateurs like to unite themselves in clubs, there is a new FT8 Digital Mode Club created through an initiative of two Austrian Amateurs. I’ve joined, you never know what it may be useful for ;-). I received membership number 608, an indication that there are quite a few who have adopted this new mode already.





~ Richard, PD3RFR
   Reprinted with permission
   Translation by Google and VE7TI

For more information and other interesting articles check Richard’s website www.pd3rfr.nl






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