That 3 kHz slice that is being occupied by FT8 on most bands is supporting DOZENS of simultaneous QSOs when the band is open. That's spectral efficiency that no other popular mode can match, not even CW. Each signal on FT8 is about 50 Hz wide, so in theory there could be 60 active QSOs without mutual interference.
The other argument is that FT8 users aren't really communicating. It's a lot like contest operation -- it's a proof of being able to communicate, not the passage of actual information -- but unlike contests, it's like that 24/7. Some hams consider all such operation a waste of spectrum, and so they consider any amount of FT8 that is greater than zero to be a waste. I don't agree with that position. As for that separation of the CW and FT8 segments on six meters, that was caused by the desire for compliance with the existing band plan. By long agreement, CW operation mostly takes place in the first 100 kHz of the band. (In the US, modes other than CW are prohibited in that portion of the band. Unlike the CW segments on the HF bands but like the first 100 kHz of two meters, digital modes can't be used there.) 50.1 to 50.3 is where most SSB DXing happens; putting a digital mode there would not be welcomed by other users of the band. FT8 therefore had to be placed above 50.3 MHz. I'll point out that there are technological solutions, including using a rig with dual receivers, an SDR with a wider input bandwidth, or an advanced SDR that can run more than one receiver slice at the same time. On Tue, Jun 3, 2025 at 4:29 PM Jim Brown via wsjt-devel < wsjt-devel@lists.sourceforge.net> wrote: > On 6/2/2025 8:41 PM, Tsutsumi Takehiko via wsjt-devel wrote: > > Allow me to make comment on bandwidth topic as I was involved and > > actually decided FT8 bandwidth as "2kHz" (as I did not know such > > popularity for FT8) on 40m/80m, wondering the proper spectrum allocation > > methodology in 2017. > > The major error that developers made way back when, and CONTINUE to > make, is to chew up way too much spectrum by spacing watering holes with > excessive spacing, and by failing to reuse/share watering holes by > operating modes that have either gone obsolete or are rarely used. It's > CRAZY for there to be 10 kHz between dial frequencies! > > This is especially true on HF, where the bands can get VERY full on > weekends with major contests, and users of digital modes often start > calling CQ on top of contesters who are using what digital users believe > is THEIR frequency. > > This wastefulness was also a major contributor to the demise of CW on 6M > with FT8. The chosen frequency was too far from the CW part of the band > for users with spectrum display to be able to monitor both modes. A few > years earlier, I was able to make QSOs into SA during a 6M TE opening > with different stations using CW and JT65, BECAUSE the JT65 frequency > was low enough I could watch both parts of the band. > > I think the cause of what was really a massive failure on the part of > developers is that they lived in their own world, failing to consult > with other users of the spectrum. This was certainly true of those who > developed the excellent Flex radios. A local contester who like me is a > serious engineer had one early on, told me that his 6500 was the best > radio he'd ever owned, but that the user interface was unusable, because > the developers weren't active hams, and had no clue about on-the-air > operating. That all changed when some great operators who saw the > radio's potential were able to get the developers to work with them on > that UI, and their radios have become very popular with contesters. > > 73, Jim K9YC > > > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >
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