Marco, You stated that " FT8 is (should be) seen as a low power high S/N efficient transmission mode". If you were struggling to hear N5J during the DXpedition, you certainly would have difficulty hearing them if they were running low power FT8. The RIBs (Radio in a Box) they used were running amplifiers, I believe 500watts on FT8.
Super Fox was/is an improvement over the traditional Fox/Hound. It permits more stations to be worked by the fox without sacrificing output power. I watched them work both Super Fox and Fox/Hound and it was obvious to me that the signals I received were generally stronger/louder when he was running Super Fox. Comparing this DXpediton to other DXpeditions probably isn't fair. The N5J group was given antenna limitations by the US Fish and Wildlife Service, who controls access to the island. You may have been able to hear them with more success if they were permitted to run directional antennas pointed your direction. Personally, I was blown away at the signal strength improvement when Superfox was tested on American Samoa and again when it was utilized on Jarvis. 73 Fred K3FRK On Sat, Aug 24, 2024 at 5:51 PM Marco Calistri via wsjt-devel < wsjt-devel@lists.sourceforge.net> wrote: > I'm with your thought, Gary and if you and others permit me, I would add > that FT8 is (should be) seen as a low power high S/N efficient transmission > mode, then it is particularly useful and welcomed for modest ham-radio > stations like mine. > > If now, to work a DX Expedition which is using SFox we would need a > multi-elements Yagi beam and at least 500 Watts of RF power, this > beautiful "FT8 concept" disappear! > > --- > > > > *73 de Marco, PY1ZRJ (former IK5BCU) * > Il 24/08/24 18:12, Gary via wsjt-devel ha scritto: > > Exactly. The reduced overall sensitivity compared to 3 stream regular F/H > was at play in my case. On 3 streams, they decoded on regular F/H at -17. > Weak, but well within the -24db decoder limit. A -17db signal on Super F/H > is outside of that decoder's limit of -16. It makes a difference for those > of us forced to use marginal stations. Also, the 1500hz bandwidth makes it > more prone to QRM, as I see it. > > I hope that DXPeditions from now on will not be using S/FH exclusively, or > myself and a lot of other small stations are going to be left out, unless > the SFX runs some power. Like 40-100w at least. I heard that N5J was only > running 10w. That could have been a big part of the problem, if true. > > 73 de Gary - W9BS > > On 8/24/2024 4:50 PM, Jim Shorney via wsjt-devel wrote: > > It is a matter of deciBels as has been documented. Each time a stream is > added in multi-stream there is a multi-dB power hit on all streams. This is > what SF avoids but TANSTAAFL. You do lose some sensitivity but at that > point you would probably not be hearing multi-stream FH either. It seems > like you were a victim of propagation. If you were copying three streams of > FH you probably could have copied SF under the same conditions. Just a > guess as there are multiple factors in play. I was decoding SF more > reliably than anything over 2 FH streams. It is rare that I am able to copy > three or more FH streams when prop is poor. Signals have to be very good. > That is not the fault of the software, it is the limitations imposed by my > antenna system and local noise floor vs. propagation conditions. > > 73 > > -Jim > NU0C > > On Sat, 24 Aug 2024 12:10:02 -0400 > Gary via wsjt-devel <wsjt-devel@lists.sourceforge.net> > <wsjt-devel@lists.sourceforge.net> wrote: > > Perhaps it is a problem when running 5 streams. But my experience was > just the opposite. I could never hear them on SFox on any band. > Admittedly, I run a low profile station with an attic antennas. From > this perspective, SFox was a huge disappointment. It wasn't until they > switched to regular fox near the end of their deployment that I was able > to finally work them on 17 and 30. They were running 3 streams at the > time. Never decoded them once on Superfox on any band, after > frustratingly listening for them all week. > > 73 de Gary - W9BS > > On 8/24/2024 11:51 AM, Jim Shorney via wsjt-devel wrote: > > But the same can be said of multi-stream F/H. I can say with certainty > that I have Super contacts in the log with N5J that I would not have if > they had been using multi-stream. > > On Sat, 24 Aug 2024 13:48:02 +0000 (UTC) > Greg Chartrand via wsjt-devel <wsjt-devel@lists.sourceforge.net> > <wsjt-devel@lists.sourceforge.net> wrote: > > > The bottom line is SF mode IS self defeating when/where conditions are > marginal AND they are always marginal somewhere in the world > > > > > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >
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