More general : it seems that it is possible to cross the pond with
stations
running less than 1W ERP (believe that BMU and AQC are abt 400-500mW) but
it needs rather long dotlengths (1 minute). So we want to take the next
step to 2-way communication we might need a more 'time efficient' mode
than
straight morse code.
Yes, exactly what we on this side are working on. We have two systems, Bill
de Carle has a BPSK variant that is coherent to a GPS data stream and the 1
Hz ticks fed into a computer parallel port. I have resurected an FSK
system I used on EME some years ago, more below.
More complicated 'coding' using multiple frequencies
could even speed up things more, using 4 frequencies we could code 64
characters in 3 'dots'.
Based on the experience that a 'very basic' QRSS QSO takes about 20
minutes
at 3 sec. dotlength this would mean over 6 hours at 1 minute dotlength.
Yes Rik, in fact the 6 hour QSO would be very difficult to make fly with the
minimum character QSO model I am using, about 250 units of data have to be
exchanged.
I studied DFCW and the linear requirement is not possible of course. So I
have adapted an FSK Model that I used previously for EME from 5 level to a 7
level FSK. This brings the QSO down to just under 2 hours for callsigns
that are what I call "reasonable", some call signs are painful from a bit
component. I will write up the minimum QSO model and the 7 Level FSK model
in the near future and let them out on here. I intend to demo the FSK model
as soon as a I have an DDS Exciter that will listen to a computer serial
port hi.
7 level FSK might sound a bit much but when FSK steps only have to be 50 or
60 milliHz the end effect is not very painful.
Larry
VA3LK
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