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Date: Thu, 25 Nov 2004 16:24:32 +0100
From: Alberto di Bene <dibene@usa.net>
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Subject: LF: Re: Linear amplifiers , MSK, and 500kHz
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smoqus@plusnet.pl wrote:

> But this must reduce the possible throughput - you throw away some bit combinations 
> (in a way similar to Compact Disc 8 to 14 bits coding).

Undoubtedly Marek, any Error Correcting Code requires the sacrifice of 
some bandwidth to
do its magic. And while this is not strictly an ECC, there is 
notwithstanding a price to pay...

DL4YHF@aol.com wrote:

> Hi Alberto,
>
> Will one of the big "pro's" of COFDM -its immunity to multipath and 
> "reflections"- really so important on LF with a very low symbol rate ? 
> - well this is just an initial thought, I don't really know much about 
> COFDM except that it is used in DVB-T (which we don't have in this 
> underdeveloped part of DL yet, hi).

Hi Wolf,
  what I had in mind was to use the multiple, orthogonal signalling 
frequencies not for their multipath rejection characteristics,
but to implement a sort of redundant signalling scheme, where you could 
have one, two, three or more slots ruined by QRM
(Loran comes to mind) and nevertheless have a correct copy, thanks to 
the error correcting capabilities made possible by the
redundancy in the coding scheme. Probably this is not orthodox COFDM, 
but I don't have a better name for it.
But these are just the kind of thoughts you have when you relax and 
close your eyes. All the gory details have to be worked out yet.

73  Alberto  I2PHD