[Moon-Net] FT8 for EME

Joe Taylor joe at princeton.edu
Thu May 21 22:11:28 CEST 2020


Hi all,

On 5/21/2020 2:47 PM, Earl Shaffer WB9UWA via Moon-net wrote:
> Well I suggested FT8 here some time ago now and all I got was crickets. 
> Nobody had commented or had tried it.

Indeed, you asked about FT8 three months ago.  It was not viable for EME 
then, since the decoder would not respond to signals delayed by the 
2.5-second EME path delay.  Now, with an optional user setting, it does.

On 5/21/2020 2:53 PM, Dave Redman G4IDR wrote:
> ... Is this possible up to the theoretical limits. ??  Or is JT65 already
> optimal in A, B, and C modes for use up to and including 23cms ? 

You ask about relative sensitivities of FT8, JT65, and possible new 
modes.  As we have implemented it, FT8 gets significantly closer to the 
theoretical sensitivity limit than does JT65.  A "slow FT8" mode is 
indeed a sensitivty winner, on suitable propagation paths.  We are busy 
implementing such a mode, but with particular emphasis on its use on the 
LF and MF bands.

As mentioned by Earl and noted by all FT8 users, FT8 has the operational 
advantage of putting everybody in one (or a few) narrow spectral slices 
on each band.  So it's easy to find QSO partners without skeds or chat 
rooms.  Everything is done over the air, with no "side channels" needed.

To my friends Valter and Hervé, and others who (like me) love CW:

I agree it's a thrill to hear your own lunar echo, and to make CW EME 
QSOs.  But looking ahead, most of us 80-year-olds (actually I'm still 
only 79, for a few months) will be permanently QRT.  Most hams of the 
future will not learn or use CW.  But they will be real hams, and some 
of them will do EME.  All of them will gain much from the wonderful 
hobby we share.

Sometimes I pine for the bygone world of commercial sailing ships, which 
happen to be very much a part of my family's history.  But I know that 
technologies evolve, and the world does not stand still.

	-- 73, Joe, K1JT


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