Friday, February 3, 2017

Now using JTDX

Many decodes per transmission cycle
Bas PE4BAS recently wrote about his results using JTDX instead of WSJT-X for JT9/65 modes. JTDX is written by Igor UA3DJY and seems to be gaining in popularity among users of this mode.

Bas mentioned that multiple decodes are possible on the same frequency at the same time. In other words, a CQ may result in multiple answers when operating JTDX whereas WSJT-X might only decode one of those stations responding.

I decided to try JTDX myself. It took only a few minutes to download and configure the audio/CAT parameters to match those used with WSJT-X. After 5 or 10 minutes it became clear that I was seeing more decodes per receive cycle than I'm used to seeing with WSJT-X.

But it could be that the band is in better shape and more stations are on the air taking advantage of that. So I decided to call CQ and, just as Bas mentioned, several stations were decoded responding to me - all within 2 Hz of each other!

Clearly the color scheme for calling stations needs to be fix but this is easy to do. These three stations responding to my CQ were all within 2 Hz of each other. WSJT-X would have only decoded one of them and I would have been unaware of the other two.

This is pretty amazing and makes me wonder how many (and which) additional stations responded to me when I previously used WSJT-X and only got one responder per CQ. Check out Bas's other posting here where he compares the two programs. The visual result of using JTDX is that the band appears more open than when using WSJT-X due to the number of decodes that take place. Igor has managed to improve ionospheric conditions with a free program!

I have not yet tweaked the levels of RX or TX and see no need to yet. I have changed the color scheme to provide better visibility of callsigns displayed - as can be seen from the screenshot, the default color scheme for stations answering a CQ is pretty poor. Fortunately, that's an easy thing to fix in the Settings>Notifications menu.

Thank you, Bas, for informing readers of your blog about this software. It is much more than a minor improvement to WSJT-X. The difference in performance is quite significant.
Incidentally, this posting, and the screenshot image editing were made entirely with my $35 Raspberry Pi/WSPR transmitter.

1 comment:

  1. Glad you like it John, well done post with your Raspberry hi. A new post on my blog about hint decoding might interest you. 73, Bas