Very well stated, separate questions. 73 Rein W6SZ
-----Original Message----- >From: "J. Moen" <[email protected]> >Sent: Jul 13, 2010 6:37 PM >To: [email protected] >Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum > >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: [email protected] > Sent: Tuesday, July 13, 2010 2:35 PM > Subject: [digitalradio] Re: Random data vs Spread Spectrum > > --- In [email protected], 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
