That seems a bit theoretical to me. If you have a mode that is very wide but 
gets its information across in short bursts, it could be said to be very 
efficient, but in practise it is efficient only if others are able to make use 
of the gaps between transmissions. If that mode needs that frequency to itself 
and cannot exist with other modes then it really makes no difference if it 
transmits on a 100% duty cycle or a 1% duty cycle it is preventing users of 
another mode from using the same spectrum. 

I think this argument is valid for the amateur bands because most digital modes 
do not have exclusive use of a part of the spectrum. They have to share space 
with other, different modes. A wide, bursty mode will prevent narrow, 
continuous ones from having a contact on the frequency (and vice versa) 
therefore from the point of view of the users of the narrow mode struggling to 
find somewhere to operate, the wide mode is occupying all of that space.

Julian, G4ILO

--- In [email protected], Rein Couperus <r...@...> wrote:
>
> Hi Andy,
> 
> well, I don't agree... as soon as you talk efficiency, you have to define 
> what that means.
> 
> For me bandwidth efficiency is 3-dimensional, it defines how much information 
> can be 
> transferred within a certain time span, within a certain bandwidth.
> 


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