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Best Digital Mode? … Not Really
20 November 2017 | by 
For the past year, as interest in the digital modes began to skyrocket, I have been reading the topical discussions and questions posted in the WSJT Yahoo Group.Since the introduction of FT8, the group's daily traffic has soared and easily occupies the vast majority of inquiry.
Far and away, most questions either involve software / computer configuration problems or inquiries involving the operational use of the software itself. I am often surprised at the range of inquiry and in almost all questions involving the software itself, it just comes down to 'reading the manual' ... it seems that hams, like so many others, just don't like to read manuals and for a technically-oriented hobby, I find this peculiar. Perhaps it's because I'm just the opposite, and will usually go over instructional material, more than once, before plugging something in or installing any new software.
Not all digital modes are 'created equal' nor with the same purpose in mind and for those new to these modes or making the transition from traditional mode operations, sorting them out can often be a source of confusion. One such user broached this very topic with his recent inquiry:
I have been using JT65 and FT8 a lot, mainly on 6m DX to receive weak signals in the noise floor. QSB is acting fast there and the 15s intervals are a major advantage of FT8 to be able to complete rare contacts.
But which algorithm is better to decode weak signals in theory and practice? Do the long intervals allow the JT65 algorithm to decode weaker signals than FT8?
If both modes are equivalent is there any reason to use JT65 rather than FT8?
Bill, G4WJS, has been handling most of the technical inquiries and I thought his reply might help others that could be wondering the same thing:
... simple answer, neither wins in all situations. Each mode in WSJT-X is designed for a certain set of requirements and given those the protocol and the decoders try to optimize sensitivity and robustness.
Bill, G4WJS, has been handling most of the technical inquiries and I thought his reply might help others that could be wondering the same thing:
... simple answer, neither wins in all situations. Each mode in WSJT-X is designed for a certain set of requirements and given those the protocol and the decoders try to optimize sensitivity and robustness.
JT65 was designed initially for EME where ultimate sensitivity was necessary and one minute T/R periods with variable bandwidths between 180Hz up to 400Hz, to cope with Doppler spreading, was deemed acceptable for practical QSOs.
FT8 is not as sensitive, a few dB behind JT65A but as you point out it is particularly suitable for multi-hop 6m Es propagation where openings can be very short. This is no surprise as it was crafted for exactly that. OTOH FT8 has become *very* popular on HF, probably because most HF QSOs do not need ultimate sensitivity and the 15s T/R period makes QSOs four times as fast compared with JT65. This last attribute is surely what is driving the massive uptake on HF on the current "easy DX" propagation bands like 20m for daylight paths and 40m for darkness paths.
JT9 was designed for HF and uses about 1/10 of the bandwidth of JT65A along with even better sensitivity. Unfortunately many users use ancient software with no JT9 support or are working through JT65 goals like WAS mode specific endorsements so JT9 does not get the attention it deserves. Although JT9 works for many on 6m, the tighter frequency tolerance required is a limitation for many with older rigs.
Both FT8 and JT65A have two pass decoders that can dig out multiple overlapping signals (similar techniques could be developed for JT9 but the need has not been seen yet).
FT8 has the AP decoder which gets a couple of dB extra sensitivity for critical decodes and also helps with truncated or interrupted messages in some cases.
WSPR is a pseudo beacon mode that uses a short message and two minute T/R period that has greater sensitivity than even JT9 despite the signal being only 6Hz wide. WSPR like JT65A and FT8 uses a two pass decoder capable of decoding overlapping signals.
There is also MSK144, QRA64, JT4, the fast versions of JT9, ISCAT, FreqCal and Echo mode. Each with a specific purpose and maybe for other opportunities they were not initially designed for.
For myself, I have yet to download the latest WSJT-X release, as I presently have no need, nor see the need to use FT8. To utilize the new release, I think I'll need to delete my older (pre-FT8) version, in order to avoid file confliction problems. My older version works very well for what I do need, and that is JT9. There are a few features on the software that I also find handy, which have been removed in the newer versions ... I think.
I can however, visualize losing out on some great DX opportunities on 6m during the summer, if the huge exodus from the CW DX mode to the FT8 mode continues to escalate. I really hate the idea of this happening but if that's what it takes, I'll install the FT8 version on my small contest-logging laptop which means building a new interface to run the 756PROIII on FT8.FT8 is not as sensitive, a few dB behind JT65A but as you point out it is particularly suitable for multi-hop 6m Es propagation where openings can be very short. This is no surprise as it was crafted for exactly that. OTOH FT8 has become *very* popular on HF, probably because most HF QSOs do not need ultimate sensitivity and the 15s T/R period makes QSOs four times as fast compared with JT65. This last attribute is surely what is driving the massive uptake on HF on the current "easy DX" propagation bands like 20m for daylight paths and 40m for darkness paths.
JT9 was designed for HF and uses about 1/10 of the bandwidth of JT65A along with even better sensitivity. Unfortunately many users use ancient software with no JT9 support or are working through JT65 goals like WAS mode specific endorsements so JT9 does not get the attention it deserves. Although JT9 works for many on 6m, the tighter frequency tolerance required is a limitation for many with older rigs.
Both FT8 and JT65A have two pass decoders that can dig out multiple overlapping signals (similar techniques could be developed for JT9 but the need has not been seen yet).
FT8 has the AP decoder which gets a couple of dB extra sensitivity for critical decodes and also helps with truncated or interrupted messages in some cases.
WSPR is a pseudo beacon mode that uses a short message and two minute T/R period that has greater sensitivity than even JT9 despite the signal being only 6Hz wide. WSPR like JT65A and FT8 uses a two pass decoder capable of decoding overlapping signals.
There is also MSK144, QRA64, JT4, the fast versions of JT9, ISCAT, FreqCal and Echo mode. Each with a specific purpose and maybe for other opportunities they were not initially designed for.
For myself, I have yet to download the latest WSJT-X release, as I presently have no need, nor see the need to use FT8. To utilize the new release, I think I'll need to delete my older (pre-FT8) version, in order to avoid file confliction problems. My older version works very well for what I do need, and that is JT9. There are a few features on the software that I also find handy, which have been removed in the newer versions ... I think.
Of course there is always the possibility that the trend will reverse as many eventually find that FT8 contacts are not all that interesting. The inability to exchange anything other than minimal required QSO information is the price paid for that extra sensitivity ... fine for that once in awhile new one in the log but not very satisfying for everyday communications.
The 'reversing trend' was also addressed in a recent posting to the WSJT Yahoo Group:
In my opinion it is nice to see a steady return to JT65 & JT9.
An all round better mode.
Still a bit short on the DX stations but I am sure they will follow soon.
Pretty much what a lot of us said would happen: an initial surge to FT8 and then things would settle down. Just another tool in the toolbox that does not have to be “better” or “worse” than anything else that has a few advantages over some modes in some areas (Es, for example) and disadvantages over others. None of these modes has to be classified as “good,” “bad,” “better,” “worse,” etc just like I don’t consider a screwdriver “better” overall than a hammer but each tool does a different thing. I suppose it’s human nature to attempt to classify things that way.
I have also seen some confusion when some are describing WSPR 'QSOs'. This is disturbing since there can never be a two-way exchange of information, all via radio (a QSO) using the one-way WSPR beacon-mode. Some may be confusing 'WSPR QSO's' for the actual Weak-Signal two-way 'WSPR QSO' modes such as JT65, JT9, FT8 etc.
Since WSPR relies on an internet back-channel exchange of information (to see where you've been heard), there is no actual on-air exchange of the data needed to claim a legitimate contact. To make such a claim would be no different than two stations, each running a beacon and calling each other up on the telephone to say that they can hear each other and calling it a two-way 'QSO'!
I have been using, and will continue to use JT9 on the new 630m band where signal levels are often too marginal for CW work but easily handled with this digital QSO mode ... otherwise I'll keep pounding brass whenever I can!
5 Responses to “Best Digital Mode? … Not Really”
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I have been using FT8 (mostly 10m RX) and it is good. Some of this is concentrating activity in a narrow slot of spectrum. OK, it is not as good as WSPR for really weak signals, but considering there are no sunspots I have copied loads of continents on 10m. In the past, people would have given up on 10m as “dead”. FT8 is proving there is plenty of life on the band.
With hearing going bad I went from voice to PSK31 added PSK63 and later Olivia. When JT-65 came out I didn’t try it for a year. I did have fun with WSPR. Soon I tried JT-65 and JT-9. Kind of reminded me of watching paint dry, but I was more then surprised by the outstanding results. I like JT-9 better then JT-65 as far as pulling really weak signals out, but I never found that much activity,as compared to JT-65.
Fast forward FT-8 came out and it blew me away with the speed and the number of contacts I could make with 50 watts or less and my 7 band 3kw Buckmaster OCFD antenna at 30 ft. Part time,as in maybe a hour a day, I was able to blow past 1000 new log entries. Then after the second month going into the 3rd past 2000 log entries without any effort. That is the draw of FT8. The other draw IMHO is that DX that I have not heard or was extremely hard to impossible for me to work, even QRO at 500 watts were now being logged for the first time. The reality is that all these DX station would have been not more then a basic exchange anyway, so what FT8 is doing is nothing more or less then a CQ TEST or a 1 minute exchange and 73 anyway.
I have been a ham for 53 yrs. Novice in 1963. I never mastered CW do too learning it all wrong. So stuck with a Tech license and with work and travel even HF and vhf was something I had very little time to do. Now retired and having more time I am relearning CW and at a blazing speed of about 15 WPM..kind of sort of… Even with bad hearing CW works, but like SSB very weak signals will not be in my logbook.
My feeling is FT8 is here to stay and will grow. JT-65 will also grow, but at a slower rate. I have little hope of JT-9 doing much. I have racked up a DXCC and WAS from LoTW and eQSL has netted me 6 awards with 4 close behind. Never had any wallpaper and this is kind of fun… That alone will keep WSJT-X growing. That all said CW will not go away and will keep increasing in numbers as well as SSB and RTTY because I really believe that in the end people still want more then Zombie radio and once you get all the wall paper using one mode, the then itch will be getting hams back into digital with PSK and CW and SSB.
This morning, just for yucks, I check a few bands and found them dead or almost dead on CW and SSB. So I fired up FT8 and made contacts on 10, 12, 15, 17, 20 and 30 meters, all within a hour. I went back and called CQ on 10 meters, 12 meters and 15 meters.. Nothing.. no contact. 15 meters one contact. 20 meters 3 contacts and 30 meters with my really bad CW no contacts… No sunspots which could be part of the problem, but with FT8 dead bands were not dead. It is part of my everyday radio working now.. It is just not the only one…
Steve, it’s really interesting to read a discussion on this subject that hasn’t descended into polemics, and that’s probably because you set the tone right in the first place. Thanks for that. I’ve been in the hobby since 1957, and licensed since 1979, so maybe I’m a bit of a dinosaur, but I still prefer SSB and CW, with the latter being my mode of choice. I can see the attractions of the various digi modes, but am not yet ready to do more than have a look at them every now and then to satisfy my curiosity. Each to his own.
Harry, I think you did the right thing by calling CQ on an apparently empty band, and it would probably be a good idea for all of us to do that more frequently. This also implies that we should all make an effort to answer CQ calls we hear, regardless of where they are from. Only then will the band activity pick up and set the ball rolling to attract more people back into the traditional modes because they can hear more going on. I guess it comes down to being the change you want to see.
Thanks all…I am very much enjoying your comments…and Colin…over the past two weeks I have made a point of calling several CQs on CW, either 80 or 40 in the late afternoon and have been truly astounded to see the high amount of good old fashioned brass pounding (keyers included!) on both of these bands. They both sound as they did many years ago. Perhaps my fear of this mode vanishing in favor of the digital modes were all for naught? With many years of quiet Sun approaching, these low bands can only get better. We even had a great west coast opening to Europe a couple of weeks ago and the band was full of CW activity … just love to see this. Maybe some have tired of digital already or maybe some are, as you suggest, ‘being the change you want to see’. That sounds like a great subject title for another blog 👍
Good article. I am a die-hard JT65A guy, with JT9 a close second in my preference, when I am seeking to get some DX into my logbook.
Despite the lemmings-to-the-sea inrush of new digital operators infatuated with FT8, there are those who enjoy and covet the conversational digital modes. Seeking more than just wallpaper, these operators take joy in meeting new people and learning about their culture, their view of the hobby, and more. Some even develop long-lasting friendships because of the conversations they have via keyboard-to-keyboard digital modes. One such mode that is still very popular, even in emergency communications around the world, is OLIVIA. See my new post here on AmateurRadio.com at http://www.amateurradio.com/come-join-the-fun-with-olivia-on-hf-shortwave-digital-mode-olivia/ for some information I put together about this mode.