I figured out that FT8 operation is similar to contest operation. The band is crowded, there is some overlapping between stations. Some hams choose a frequency, stick to it and call. Some others listen (or read with FT8), browse the band, and try to contact the ones who call. During a contest, the portion of band devoted to SSB is fully occupied. This often the same with FT8, especially if the propagation is good.
Let’s compare the band slots. SSB needs 2.5Khz, FT8 needs 50 Hz. The station « density » is 40 per 100 Khz for SSB and 20 per KHz for FT8. On 20m for example, about 300 KHz of spectrum allocated to SSB can accommodate 120 QSOs. In order to accommodate the same number of QSOs with FT8, we would need a 6 KHz slot on 20m. In case FT8 remains or becomes more and more popular, if we want to provide the same opportunities to FT8 as SSB’s (an provide some band portions dedicated to DX), we can consider expanding the FT8 slot. If we do the same calculation on 40m (let’s say there is 120KHz available for SSB), so 48 QSO for SSB, the is a need of a 2,4KHz slot for FT8 in order to provide a fair balance between SSB and FT8. We can apply the same reasoning to other bands. Considering the quick decline of JT65 operation due to the popularity of FT8, we cannot predict if this popularity is sustainable. Maybe there will be a more attracting mode popping out in the next future. If FT8 becomes one of the preferred modes to make QSOs, my opinion is that there will be some needs to review band plan. Best Regards Phil, F5FDV Le 22 nov. 2017 à 05:19, Gary Kohtala - K7EK via wsjt-devel <wsjt-devel@lists.sourceforge.net> a écrit : Perhaps it is time to phase out JT65 on HF, in favor of FT8 and JT9. That would most certainly be best use of spectrum, considering the bandwidths and efficiency of those modes. Best regards, Gary, K7EK From: Black Michael via wsjt-devel <wsjt-devel@lists.sourceforge.net> To: WSJT software development <wsjt-devel@lists.sourceforge.net> Cc: Black Michael <mdblac...@yahoo.com> Sent: Tuesday, November 21, 2017 11:41 AM Subject: Re: [wsjt-devel] Feature Request of FT8 TX Frequency limitation less than 2kHz Is anybody on JT65 running out of room at 500-2000 offset? Why do we need to change anything? Yes...SOME rigs can do 3000, many cannot. So if you want to transmit above 2500 you may be losing a lot of people (including DXpeditions). Moving the 7.074 to 7.073 means anybody running an older version will miss out on the lower offset by default. FT8 can also decode overlapping signals fairly well... Are you really unable to find a spot to transmit? Note that the popularity will decrease as everybody gets everybody else worked. On Tuesday, November 21, 2017, 10:07:11 AM CST, Libor Holouš <ok...@email.cz> wrote: Hello guys.. According this theme I'd like to ask about expanding the band possibility. FT8 seems to be very popular these days and there are some DXpeditions operating there, so 2 kHz is not enough space for all that traffic. The extreme is 40 and 20m, but when propagation allows, the other bands too (on higher bandsis not possible to see most of EU traffic, from DX side it must be crazy :-) I'd suggest add another kHz lower. Lots of newer radios got 3kHz filter, so it is possible to hear whole band easily. Beginning of band should be used by DX stations (expeditons) using fixed freq. while using split operation (for transmit are freq. bellow 200Hz and above 2.4kHz practicaly unusable). For JT65 users then should be less possibility of intrusion and there will be more space for non-dx operations too. Example: Expedition tunes in VFO B 14072kHz, audio sets between approx. 1100-1300. VFO-A for RX tunes 1kHz higher 14073 and sets 3kHz filter. Sets Hold TX freq. CQ message "CQ UP DX1DX square". RR73 should be a standard in this case. User, normaly set on 14073 should see expedion calling betwen 100-300Hz, what is readable, but difficult to transmit there directly, but can use 300-2400Hz for call easily, if sets split on the radio, can easily use up to approx. 2930Hz, still readible by expedition. And voila: 14073000+2930+60Hz = 14075990Hz. So intrusion to JT65 band is solved. The only expedition was using radio split was 5T5OK - used UP2 - but it was unfortunately in JT65 band. Extending band by 1000Hz lower could help a bit. I don't know the details of earlier mentioned developed DX mode in this discussion, so for today's conditions it is possible solution without some SW development (except overwrite freq. list in future) It's theme for discussion. FT8 started revolution in digital modes, and is much more popular now, than PSK31 was. The JT65 was not popular for me, due looong time procedure of the QSO, if it was DX there, it was for several coffies, until got QSO. It's still not as fast as RTTY or PSK, but there is no space for macros, most users use on PSK (Everybody seen the QSO, while complete PC and SW setup, WX, age and lots of rubbish was send on PSK), so waiting for the qso was also sometimes boring. So, lets discuss.. :-) 73 Libor OK2ZO ----- Original Message ----- From: Black Michael via wsjt-devel To: WSJT software development Cc: Black Michael Sent: Tuesday, November 21, 2017 3:05 PM Subject: Re: [wsjt-devel] Feature Request of FT8 TX Frequency limitation less than 2kHz Although FT8 has "intruded" on the lower part of the normal JT65 spot I don't see it as a problem. There aren't that many JT65's out there...and, in the past, I've seen plenty of JT65's "intruding" on the JT9 area. It's quite natural to bump up the 2kHz limit when the band is crowded. ALl has to do with the average bandwidth of a receiver typically being 2400 and higher. So far don't think I've seen any FT8's above 2500. The only reason WSPR is excluded is because the same people that wrote WSPR also wrote WSJT-X...otherwise it probably would not be excluded (e.g. there are other JT65 programs that don't excluded the WSPR area ). de Mike W9MDB On Monday, November 20, 2017, 11:10:15 PM CST, Tsutsumi Takehiko <ja5...@outlook.com> wrote: Hi all, It is great to observe the popularity of FT8 format among non-wsjt-x experience in the past and I have a proposal to add the following feature for these. If I miss any consideration to my proposal, I welcome your comments. Regards, take de JA5AEA ----------------------------------------------------------------------------------------------------------------------------------------------------- Please add the feature to limit FT8 TX frequency less than 2kHz. Reasons are stated as follow. 1. The working frequency table was and is designed and planned that the width of FT8 is 2kHz. However, the limitation feature of 2kHz to the operator has not implemented to wsjt-x software. 2. Recently we observe above 2kHz communication practice by operators who does not know above design concept and the interference to adjacent wsjt-x channel such as JT65 is created. 3. Such TX frequency limitation practice is implemented to JT65 operation at 30m to protect WSPR channel in wsjt-x software. Some may object the implementation by the recent FT8 traffic expansion. But my position is that these traffic un-balanced problem should be separately solved by the optimization work of the working frequency table in near future. 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