Your figures for digital modes seem to assume we can use all the band
from the bottom. In fact, digital starts at typically x.070 so there
is really only room for half the number of digital stations. Also, if
you can really go up to x.150 why has ROS jumped on top of Olivia when
there is another 40kHz to play with? When you look at the bandplans
digimodes only have about 40kHz per band which makes us very much the
poor relation.
I don't think digital voice will ever replace SSB, any more than PSK31
and other spectrally more efficient modes will replace RTTY. Radios
have a long lifetime. But unlike digital modes whose bandwidth is
fixed, phone can communicate using reduced bandwidth. Look what
happens in a contest.
Julian, G4ILO
--- In digitalradio@yahoogroups.com
<mailto:digitalradio%40yahoogroups.com>, KH6TY <kh...@...> wrote:
>
> Your are right, Julian. The current regulations mostly protect phone
> users from interference by other modes and digital users are left to
> figure out how to share what space is left. The division is
> approximately 50-50 between phone and digital "what the FCC calls
> 'data/RTTY'". This is a holdover from the days when the only digital
> mode was CW and the only data mode was RTTY.
>
> Phone is the easiest to use human/rig interface, and the easiest to
> learn, so it is the preferred interface for most. Using 20m as an
> example, 150 kHz is allocated to RTTY/data (digital) and 200 kHz to
> phone. Assuming a 2.2kHz wide phone mode, there is room for
> approximately 90 phone stations. Assuming an average of 0.5 kHz wide
> digital modes, there is room for 300 digital stations. If everybody
used
> a 2.2 kHz wide digital mode, there would only be room for 68 digital
> stations.
>
> CW is still the most-used digital mode, about .2 kHz wide, depending
> upon the speed, then RTTY, and now, PSK31, are next, and all the other
> digital modes have to make do with whatever space is left.
>
> The phone operators could complain that THEY are the second-class
> citizens and have not been allocated enough space in proportion to
their
> numbers!
>
> What is really needed is digital voice in a more narrow bandwidth,
> instead of "CD" quality digital voice with a bandwidth of 2200 Hz,
> because there simply is not enough space for everyone to use wide modes
> of any kind. That is already possible today by combining speech-to-text
> with text-to-speech, but the voice is not your "own", but synthesized
> voice. Dragon Software's "Naturally Speaking" 10 is now good enough
> speech-to-text with about a 1% error rate with enough training, and my
> DigiTalk program for the blind ham will speak the incoming PSK31
text as
> fast as it comes in, so that is essentially "phone" in a 50 Hz
> bandwidth, but without your "own" voice, and unnaturally slow speaking.
>
> 73 - Skip KH6TY
>
>
>
>
> g4ilo wrote:
> >
> >
> > I'm not sure I follow this argument. The fundamental problem is that,
> > within the area allocated for digital modes, there is not enough
space
> > for many simultaneous contacts to take place using a 2.2kHz wide
mode.
> > This has not hitherto been much of a problem because until now there
> > has not been much demand for using wide band digital modes. People
> > live with interference from Pactor etc. because it comes in bursts
and
> > does not completely wreck a QSO.
> >
> > If "hordes of operators wanted to use ROS" then without the ability
> > for them to expand upward in frequency the digital modes sub band
> > would become unusable for anything else. All your current legislation
> > does is protect the phone users from interference by other modes and
> > make digital users second class citizens confined to a ghetto where
> > "anything goes".
> >
> > Julian, G4ILO
> >
> > --- In digitalradio@yahoogroups.com
<mailto:digitalradio%40yahoogroups.com>
> > <mailto:digitalradio%40yahoogroups.com>, KH6TY <kh6ty@> wrote:
> > >
> > > Imagine also if spread spectrum were allowed anywhere in the current
> > > phone and upper data segments. The complaints about NCDXF and
Olivia
> > QRM
> > > from ROS would be nothing compared to what it is already if spread
> > > spectrum were allowed anywhere in the same bandwidth as phone, and
> > > hordes of operators wanted to use ROS, and not just a relative few.
> >
> >
>
