Thursday, January 12, 2017

JT-65 and the Flex

I decided to give JT-65 a whirl a couple days ago.  JT-65 is a weak signal protocol developed by Princeton physicist and Nobel Laureate Joe Taylor K1JT, and is designed to  augment contacts using meteor scatter and EME.  The protocol uses FEC and can literally hear signals under the noise.  There is a HF variant called JT-65 HF so I decided to start there.  I downloaded JT-65 HF client

and it worked but on reading more I found WSJT-X is the one being upgraded and maintained so I switched to that client

Setup with the Flex 6xxx radios is trivial.  Under file open settings, and append as needed. 

Turn on RX stream 1 and TX stream in DAX

And set the audio input to PC and turn on DAX

Set the audio level in DAX TX stream to make sure the ALC mark on the level meter is not reached 

I run about 20W.   (Note I made this shot before I had the ALC set correctly the bar should be either green or just yellow NO RED)

JT-65 is an alternating mode.  One station transmits for 48 sec and then stops.  The data sent in that 48 sec is decoded and displayed in the left window.

During the 12 second window you decide what you want to do.  In the above I note K4CMS is calling CQ so I double click his call in the left window and his call is transferred to the right.  Enable TX is also enabled.  At the completion of the 12 sec my transmitter turns on for 48 sec and calls K4CMS.  He hears me and replies with a report, I ack and send him a report, we exchange 73's and I log the QSO.  It is necessary to have very close temporal coordination (meaning your clock and the other stations clock must match very precisely.  For that I use a client called Dimensions 4.  

This software automatically links to time servers and keeps my puter clock very close to
 0.0 seconds error.

The interesting thing about JT-65 is how well DX can hear you.  The  WSJT client automatically reports out to PSKreporter

All the little ovals are stations that report hearing me including VE9CD up in Canada.  As the night progresses my 20W is easily copied by stations in the Middle East Africa Russia and all over Europe

There is a lot more to read and know, in fact it's addicting and a lot of fun.  Give it your own whirl if you have a Flex 6xxx radio

73  W9OY