WSJT-X and DX with JT9 and JT65

Last week I came across JT9 as a mode for DX on HF. I’d not come across it before (possibly being side tracked with WSPR), but before I knew it I was downloading WSJT-X, reading the tutorial and running it up.

However, first attempts to receive were a complete fail. I was sure of success as it was when there was no interference (for once) and I had heaps of JT65 signals roaring in and system time was in sync to ~100 milliseconds. But not a single decode.

I then proceeded to just give it time and let it run some 24 hours. But still nothing…

A bit of searching around the net revealed I wasn’t the only person who had troubles decoding with WSJT-X. Further, it seemed maybe that for those who had troubles all used to work with version 1.1 of WSJT-X.

I proceeded to download WSJT-X 1.1 and lo’ an’ behold suddenly I was decoding signals left right and centre. Both in single JT65 mode (for which there seems greater activity) and also in split mode decoding both JT65 and JT9 transmissions.

Since then I’ve tried again with version 1.3 and also 1.2.1 (a couple of times), but for the sake of me I can not get decodes with either – oh, except a single decode once… And looking on pskreporter (a great site BTW) it would seem very few are using the latest version of WSJT-X. Further, looking at a WSJT-X changelog I note there were changes starting with 1.2 about how the sound hardware was accessed. So I wonder if maybe that’s had a flow on effect to those running on Windows XP (such as my shack PC).

Anyway, at least I have a version that works (just a shame some nice waterfall improvements came in in version 1.2) so I proceeded to try some contacts. My first was with VK5HAM but I made a fair mess of things as I wasn’t as comfortable with the UI as I thought I was. Anyway, the one I was most impressed with was with HA1AD. Details were:

Their grid square: JN87
My grid square: QE37
Mode: JT9
Freq: 14.078850 MHz
Report sent: -06
Report received: -09
Distance: ~12,995
My power: 5W

That is indeed my first true (ie. bi-directional) DX contact.

After that, I was hooked and tried a few more, but often shooting too far (15,000+ kms). It’s amazing how quickly the time passes by with these modes.

So, if you’re yet to try these modes then I highly recommend them. They take WSPR a step further, and with reverse beacon networks such as PSK Reporter you’ve got everything you need (ie. WSPR beaconing but with option for proper QSO contacts)!

One last thing though before I go. Later on my interference returned, but to my surprise WSJT-X kept on decoding. The following two images show WSJT-X picking signals out of the noise. If you take a look at the waterfall @ 23:23 and then just near 1200Hz you can see the signal (just) from ZL3HAM, but at the same time you can see the wonderful interference I enjoy.

Although an extreme example, I have actually had QSOs in amongst lesser interference with WSJT-X this week-end. Something I would have struggled with voice and many other digital modes.


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