David,
LF,
Very
interesting you wrote :-
This is a very efficient mode.
The magazine 'Dubus' this quarter has an article on communicating over the
horizon with light by reflecting light modulated by JT65 off the clouds.
I have
just seen this mail via the Spectrum Lab Group copy below.
Gary –
G4WGT
Hello Walter
Yes the time for a block is very slow - in fact around 15 minutes.
However, we don't mind if we spend a whole evening to complete a QSO
as our goal is to extend the distance for optical cloud bounce beyond
the 209 km we have presently achieved with WSJT. Our experiments to
date with a single tone show that the optical cloudbounce can work
effectively at milli-Hz bandwidths and give around 30 dB improvement
on WSJT. The thinking is that MFSK in say 2 mHz steps over 340 Hz
would allow around 17 bits so two blocks would allow a callsign to be
sent with Kotter-Vardy source encoding at 28 bits per callsign. Thus
it would take an hour to send two callsigns. Because the system is
very slow it could initially be decoded by eye from Spectrum Lab and
if successful we could perhaps output the Spectrum Lab data to
automate the process - but this is for the future.
As Wolfgang has intimated soundcard stablity is also an issue but
this should be resolvable by GPS locking if we find the approach to
be viable.
Happy New Year
Rex VK7MO
Interesting result Jim / Jay.
I assume that the figure that varies
between -17 and -23 is the receive value in dB.
Given the observation about local noise
then it may be the case that UK
- USA
could be achieved with 6 to 9dB less power.
This is a very efficient mode.
The magazine 'Dubus' this quarter has an article on communicating over the
horizon with light by reflecting light modulated by JT65 off the clouds.
Clearly various JT modes are being used
at both extremes of the EM Spectrum. No wonder it's creator also holds a
Nobel prize for Physics.
The total number of decodes at this QTH
was 14. Most occured between 2348
and 0012, when there were 10 decodes out of a possible 13. The first decode
occured at 2300 and the last at 0102. So these are over a similar period of
time to G3XVL's reception, although differently distributed.
I think more decodes would have occured if the level of mains noise here
last night had been lower.
