FT8 SuperFox decoding

John, G3WKL

Probably, like many other Flex users, I have taken part in the K8R testing of the "beta" FT8 SuperFox (SF) mode and experienced decoding issues. The opinion on the wsjtgroup chat seems to be that the SNR maybe too high (outside the range +4 to -15dB) as well as latency issues due to K8R being a remote op. This post is not aimed at bringing that discussion onto this forum but to ask the question of Flex users, who have decoded K8R, the settings that they found useful

On Saturday 13th I could see and hear the SF transmissions on 17 and 15m, but despite trying different combinations of AGC mode, AGC-T settings and pre-amp gain (inc -10dB attenuation) I did not manage any decodes, during the hour or so that I tried. Without decodes I didn't get an SNR report, but the S meter showed about S3, which is above the noise floor

Setup here is a Flex 6700 and half-wave sloper and/or a low FD4 windom, both on long feeders, so apart from a great radio not a station to expect signal overload from the middle of the Pacific!

73 John, G3WKL

Erik Carling EI4KF

13 July 17m

240713_063315 18.095 Tx FT8 0 0.0 396 K8R EI4KF IO54
240713_063330 18.095 Rx FT8 14 0.3 748 EI4KF K8R -10
240713_063345 18.095 Tx FT8 0 0.0 396 K8R EI4KF R+14
240713_063400 18.095 Rx FT8 14 0.3 750 EI4KF K8R RR73

11 July 15m

240711_080015 21.091 Tx FT8 0 0.0 2355 K8R EI4KF IO54

240711_080030 21.091 Rx FT8 10 0.3 753 EI4KF K8R +08

240711_080115 21.091 Tx FT8 0 0.0 2355 K8R EI4KF R+10

240711_080130 21.091 Rx FT8 14 0.3 750 EI4KF K8R RR73

I had no problem decoding K8R for a very long time on these occasions. I worked him on very few calls to him.

On 12 July I listened to his FT8 on 15m but, unlike the previous day, had no decodes at all. He was less strong than on the 11th but still a reasonable signal and I did work KH6 on normal FT8 so the band was open well enough. I could not make any difference to the decoding failure with my 6400M no matter what I tried including AGC, AGC-T and antenna gain. I also varied filtering width to no avail. I changed radios and that did not help. I tried changing antenna from my beam to a 40m band vertical but that did not help either.

SuperFox needs improvement.

Erik EI4KF

Mike-VA3MW

I know they mentioned latency, but I would like to see a lot of details.

And, hopefully, they were not trying to run WJST at the operator end when they should be running it at the radio end. There is too much AF Data loss doing it that way.

John, G3WKL

Thanks for the comments, guys.

73 John, G3WKL

K5XH

I found them on 15 yesterday and they were stronger than I have heard them before. They were a consistent 0 db. But, I could not decode them except every once in a while. Apparently what others are saying is true about decoding a strong signal. I rotated the beam about 30 degrees and the copy improved.

73, Mark K5XH

Erik Carling EI4KF

But, as above, I worked them at +10dB and yesterday they were +15dB at times and no decoding issue. We don't know but I suspect Mike VA3MW has surmised correctly the problem. Bottom line is that it's not our Flex radios at fault and I'm sure the early bugs of SF will be ironed out in due course.

John, G3WKL

Thanks for the comments, guys - much appreciated

I found the problem, or more correctly it was pointed out to me in another forum. I wasn't launching the wsjtx.exe file from the \bin folder (so it wasn't picking up the files needed to decode SF)

The problems with decoding higher SNRs has been solved it seems with -rc6 released on 19th July - I'm decoding K8R at +08 a few minutes ago on 21091kHz using a simple wire antenna.

Fairly subjectively I am finding the SF decode works well with AGC OFF, AGC-T around 90 then adjusting DAX so that the RX audio on the WSJT-X program between 30 and 60dB

73 John, G3WKL

Tim Osborne

Hopefully not too off-topic.

I seem to have issues using DAX RX1 with 2.7.0 rc6, I had to move to DAX RX2. Common issue/bug?

Had to change the CAT setup too, from COM port to TCP. That's OK though temporarily frustrating.

(I'm operating remotely if that makes a difference)

Tim Osborne

Hmmm. In case it helps anyone, DAX RX1 works great on the radio locally, but not remote. For that I used DAX RX2. I was able to raise N5J easily from WA state (not much in between there and here except water).