SuperFox is a new iteration of Fox mode for FT8

SuperFox was introduced to eventually replace the conventional Fox mode for use by DXpedition operators when using FT8. The mode was created by the WSJTx developers in response to requests by DXpedition operators. It is currently in Beta and being tested on American Samoa before moving to ‘production’ mode later in August on Jarvis Island.

What are the limitations with conventional Fox mode?

The limitations can be broken down into four areas.

• First, multiple streams of signals drops the amount of power output for each stream. Personally, this is the biggest problem for me as a Hound on the receiving end. The more streams the Fox uses, the harder it is to hear the Fox and to work them. The Fox, when he/she hears you, places your call in a queue to be worked by one of the streams. When your turn comes, the Fox comes back to you. The problem is you might not hear that particular stream. Or you hear it, respond to it, and then - because the power output is low from the Fox - you don’t hear the stream with the RR73.

• Second, capacity. One of the reasons for creating Fox mode in the first place was to increase the amount of stations worked at one time. Obviously, only one signal on FT8 limits you to how many stations you can work in a minute. Increasing the number of streams increases your capacity, of course, but you can only add so many steams before no one copies you any more. In my experience, the most streams I’ve copied is six - but not consistently. Better is three streams, but even then, it is highly dependent on propagation (as are all streams…). I don’t know what the goal of SuperFox mode is in relation to SSB or CW rate, but my assumption is that the attempt is to make it equal or better - and probably better. After all, the goal of a DXpedition is to work as many hams as possible on as many bands as possible given the limited amount of time the DXpedition is on site - and increasingly, how long to get back to the same place again later. Time and permissions to go to a site is limited. For example, it has been 20-some years since Jarvis was last activated. You’d want to maximize the number of DXers worked given the difficulty of getting permission to operate from a rare site.

• Third, Security. Pirates have been spoofing DXpeditions since the beginning of time and FT8 is just another mode to pirate a call again. Any ham can activate Fox mode in FT8 and operate. And pirating begins.

• Fourth, deliberate QRM. Again, deliberate QRM has happened since the beginning of time (why people are sick enough to do this is weird). In Fox mode, there is an easier time to do this because of Fox’s unique feature that moves a station out of the main band area above 1000 Hz to below that where the Fox is operating. Theoretically, it should be ‘quieter’ there and the Fox should hear you better because you are on the Fox’s frequency. So deliberately QRM the Fox frequency and you effectively block the Fox from hearing the station just moved to be worked. Or, block the Fox’s transmissions so DXers can’t hear them.

Advantages of SuperFox mode in WSJT-X compared to traditional Fox mode

SuperFox mode directly addresses these issues and provides a couple other advantages.

• As noted above, under traditional Fox mode, power is reduced for each stream added by the DXpedition. SuperFox does not have this limitation. If the station is putting out 100 or 1,000 watts, the FT8 streams are putting out at 100 or 1,000 watts - whatever the DXpedition is operating. This is a big deal for me because the the chances of now hearing the DXpedition are much better given any level of propagation.

• In terms of capacity, SuperFox utilizes fully 9-streams to send out signals. Fully optimized, that means you could get 18 contacts a minute or over 1,000 QSO’s per hour (if my math is right!).

• And pirating will be more difficult. In order for someone to use SuperFox mode, they will need to have a security code provided to them by a reputable DX association. The initial codes will be provided by the Northern California DX Foundation and it is expected that other organizations will be added. These organizations will vet the DXpedition to ensure legitimacy before providing the code. If you don’t have the code, you won’t be able to send it SuperFox mode. In addition, the Fox will also send out a ‘call verified’ message to the Hound so you know you’re really working the DXpedition.

• Deliberate QRM will also be much more difficult. The traditional Fox mode transmitted on a very narrow bandwidth - like 50 Hz per stream. SuperFox transmits over 1500 Hz wide. I suppose you can try and blot that out with some other signal, but FT8 is so good at decoding, that might not work either.

• An enhancement is a tenth stream that is used to send ‘free messages’ by the DXpedition. For example, you could be transmitting on 14.091 and put in your free message that you are also on 21.091. Or you are QRT until 2100z. Or whatever. The Fox never had the ability to let DXers know what was up next on FT8 until this mode.

• Another note is that Hounds do not have to transmit above 1000 Hz as in traditional Fox mode. They can transmit wherever they want, including below 1000 Hz, creating a little more space within the bandwidth to work the DX station.

Impressions

Creating and testing software - especially testing - is a difficult task. Can you test with all of the use cases? Hard to do since working in a controlled environment doesn’t necessarily reflect reality on the ground in a real environment. That’s why the developers decided to use American Samoa as a real-world test before using the mode on the critical Jarvis Island DXpedition.

And issues were found! Hounds were not necessarily copying every transmission even though the DXpedition was loud into their station. On the Fox side, the entire transmission didn’t get out, missing the first part. Updates to the software - on both the Fox and Hound side, were fast - often updates daily on the Hound side of the software.

This is how iterative software is supposed to work. You don’t want these problems happening on a DXpedition that may not get back to an island (Jarvis) in 20-more years; you want to work as many hams as possible while you’re there.

And working the SuperFox is fun, at least from my Hound side. I had stopped using the Spectrum on the waterfall for FT8; I never used it. I reactivated it for SuperFox and when their signal hits the Spectrum, it’s an interesting pattern that you see.

I also never have the volume on for FT8, but I turned up the volume a bit to hear the SuperFox signal. It sounds a lot like R2D2! I’m sure I’ll lose that fun fascination, but right now, it’s great.

The best part? With the DXpedition not decreasing power with every stream, seeing 9-streams come through on their transmissions is awesome. Especially working them on one call with my modest 100-watt signal into a vertical here on the East Coast working into the Pacific.

I’m impressed with SuperFox. I think it will add a whole new dimension to how DXpeditions operate. For example, do you need three FT8 stations now or will two suffice because your capacity to work stations is so much better? Maybe you can use that extra station to operate another CW or SSB station on other bands because you’re now getting far more bang for your station size than before.

It’s going to be a fun future.