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Re: [CQ-Contest] Contesting and the FT8 Revolution

To: Bill Coleman <aa4lr@arrl.net>
Subject: Re: [CQ-Contest] Contesting and the FT8 Revolution
From: David Gilbert <ab7echo@gmail.com>
Date: Fri, 2 Jul 2021 18:01:58 -0700
List-post: <mailto:cq-contest@contesting.com>

I've gone through this stuff in detail with someone who knows far more about digital signal processing than either of us, and everything I said is possible with the exception that I will acknowledge that synchronous operation has advantages.  My postulation does NOT involve adhering to the FT8 or FT4 protocol as you seem to suggest below.  I proposed a mode similar to FT4 except wider bandwidth (which dose NOT necessarily degrade S/N as you claim) and a different set of other parameters ... plus conversion to CW instead of fixed text blocks simply to make it more adaptable to common contesting practice.

I don't care what you say ... it can be done, but it's going to take somebody to work it up from scratch instead of trying to port FT8 or FT4 to a different user interface.  Just about everything you said below is wrong simply because you're stuck in that mental trap.

I will say again since nobody seems to get it ... FT8 and FT4 as implemented by WSJT-X are not some new invention that locks all other similar efforts into the same set of boundary conditions that K1JT chose.  K1JT made very clever use of modern signal processing to create FT8, FT4, and other similar modes but he chose a VERY restrictive set of boundary conditions in order to implement his own particular vision.  Those same modern signal processing techniques could be implemented with different boundary conditions to give ham radio (and in particular contesting) a much cleaner and more usable interface.  Go read K1JT's descriptions of what he did and what techniques he used, and if you then do a bit of searching you will find lots of technical discussions of those same methods applied in different ways to other tasks.  WSJT-X is unique, but the the science behind it is not.

I know that I am flogging a dead horse here, but it frustrates the hell out of me to see the opportunity that is being squandered simply because the guy that came up with the first popular manifestation of modern signal processing had such a limited vision of what it should be.

Dave   AB7E



On 7/2/2021 10:39 AM, Bill Coleman wrote:

On Jun 21, 2021, at 2:59 PM, David Gilbert <ab7echo@gmail.com> wrote:

Everything you just said there is the fault of WSJT-X as a user interface ... 
not FT8 or FT4 as a mode.  They are NOT the same thing.  WSJT-X is simply the 
narrow and restrictive vehicle by which we have been exposed to the exceptional 
weak signal capability of modern digital processing (forward error correcting, 
Costas array processing, etc).  We'd all be having a LOT more fun with a more 
open ended interface ... possibly with these parameters:

1.  wider individual signal bandwidth, such as maybe 200 Hz instead of 83 Hz.
A wider bandwidth would potentially decrease the sensitivity of the mod

2.  fully tunable over the typical digital sub band (like RTTY does)
There’s absolutely nothing stopping you from running FT8 or FT4 anywhere in the 
digital sub-bands. You may not have many QSOs there, but it is possible.

3.  Asynchronous in time ... i.e., not locked to a discrete and specific clock 
window
This requirement is fundamentally incompatible to the way that FT8 or FT4 work. 
The fixed transmission / reception windows are clearly a part of the mode.

4.  shorter blocks of data with continuous feed of the blocks
Shorter blocks? The blocks today only convey 77 bits (BITS!) of information. 
That’s right, it takes nominally 15 (or 7.5) seconds to transmit 77 bits 
(BITS!) of information.

And continuous blocks don’t work either.

5.  sent via text blocks on the transmit end ... exactly as DVRs and contest 
loggers do now
Remember the 77 bits (BITS!) mentioned earlier? Each transmitted block has a certain 
structure, and typically contains the two callsigns (caller and callee) and a little bit of 
additional text. There’s no much room for sending any random text, because 
there’s only a few bits available to on each sent block.

6.  displayed as text or converted to audible CW (or even digital voice) on the 
receive end
Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901


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