This question of bandwidth for various modes and where to squeeze in the wider modes is a good topic. Reminds me of the folks who really like enhanced fidelity SSB (3.5 out to nearly 5 kHz), or AM. There are many bands at certain times of day that have lots of space for those modes, but I'd hope those hams would be kind to the rest of us, for example during a contest or when certain bands are chock-full. I think if 3 kHz SSB is ok, that 2.25 kHz modes (ROS as an example) should be ok, as long as the frequencies chosen are prudent for the band and time of time. That discussion is entirely separate from the US legal questions about SS modes on HF.
Jim - K6JM ----- Original Message ----- From: g4ilo To: digitalradio@yahoogroups.com Sent: Tuesday, July 13, 2010 2:35 PM Subject: [digitalradio] Re: Random data vs Spread Spectrum --- In digitalradio@yahoogroups.com, Alan Barrow <ml9...@...> wrote: > > - Simplistic bandwidth comparisons that do not factor in total > throughput. (IE: The effect of processor gain, FEC, etc). I don't think > ROS was stellar here, but the idea that a wider mode for X data rate is > worse than a narrower mode is flawed. Otherwise we'd all be using RTTY. > FEC increases bandwidth for the same data rate, but the trade off > surfaces over sustained measurement in real (difficult) HF conditions. > Skip's work did show there was not a big win for ROS, so we arrived at > the right spot. But many were banning just because it was wider than > their favorite mode! I don't know if that is a dig at one of the arguments I have made in the past, but I do believe that 2.25kHz ROS was too wide for our existing HF bands. Regardless of the merits or otherwise of a mode, people can't go on inventing new modes unless they can also come up with a place for them to be used that doesn't squeeze out existing users. Even three channels was patently inadequate for the number of users wishing to use ROS with the result that most of the contacts made, as evidenced by the spots posted here, were anything but weak signal DX as the chances of finding 2.25kHz of 20m unoccupied are pretty slim at any time. Julian, G4ILO
