Hello group,
just some ideas regarding the optimalisation of QRS speed for long distance
tests (skeds) :
1. DFCW will speed up things by a factor 3
2. For QRSS with rather long dotlengths (10-30 sec.) and using "full
break-in" it should be possible to indicate when the other station can
increase speed (or has to decrease). It could be agreed that sending a
"dot" just above the TX frequency means "speed up" while sending a carrier
just below means "speed down".
An example :
Assume a sked between M0BMU and UA9OC, both starting at 30 sec./dot. M0BMU
transmitting on 137770.0Hz and UA9OC transmitting on 137772.0Hz. Next
assume that M0BMU starts transmitting his own call. If UA9OC receives the
"M0" at good strength he could transmit a 30 sec. dot on 137770.2Hz during
the pause between the "0" and "B" (that pause takes 180 sec. at 30 sec/dot,
so a 30 sec. dot fits in well) . M0BMU know that he can speed up to 10
sec/dot (starting with the next character "B"). Now M0BMU is transmitting
at 10 sec/dot but later the QSO propagation is fainting, UA9OC can indicate
that by sending a 30 sec. dot on 137769.8Hz so M0BMU knows that he has to
go back to 30 sec/dot (the 30 sec. "indicator" just fits in a pause at 10
sec/dot).
I know that the above sounds a bit complicated, but it would allow an
optimal "use of propagation".
73, Rik ON7YD
At 20:25 20/03/2003 +0000, you wrote:
Dear Ed and friends, LF Group,
Thanks for sending the report of your UA9 expedition. It was very exciting
to see the first LF signals from Asia. In spite of the problems, achieving
the first Asia - Europe QSOs and successfully being received in, and
receiving signals from, ZL means it was a great achievement; I look
forward to the next time!
The UA9 - G propagation seems to be quite similar to what we experience
during the transatlantic tests - occasionally the propagation is
excellent, and a QSO is possible with quite fast speeds. But sometimes you
see no signals for several days, which is really frustrating, especially
if you are on an expedition. With the recent X-class solar flares, it is a
good thing you were in Siberia last week and not this week!
As far as I know, there have only ever been a handful of successful QSOs
using QRSS30 before last week, so we are still all learning how to do
this. Operation with QRSS30 and longer dot lengths is difficult because it
takes such a long time, and there is always a danger that propagation will
disappear before the QSO is finished. So it is important to use a
procedure that uses the smallest number of characters. But at the same
time, there has to be at least the exchange of callsigns and signal
reports to make it into a "proper" QSO. A problem with inventing new
procedures is informing all the stations that the new procedure exists. It
is not easy for stations who do not have internet access, or do not speak
much English, so there is always going to be some confusion unless the
procedure is kept very simple. I think using procedure signals for sending
faster and slower might help sometimes, but the problem is that the QSO
has to start with both stations sending slowly to be sure they can copy
each other - so they can only speed up after the first 2 overs, by which
time more than 50% of the QSO is complete,and so not much time is saved.
If one station has a higher ERP than all the others, as Ed did, it would
make sense for that station to send faster. I guess about 1/3 the dot
duration would be right (3s/10s, 10s/30s etc) - even if faster sending was
possible for one station, it would not make much difference to the total
QSO time.
It is quite common to see stations doubling with each other, which wastes
a lot of time at QRSS30. A good way to avoid that is to use break-in.
Rik's QRS software allows you to receive between characters and/or
elements, which enables you to see if you are doubling, or if you are on
the same frequency as someone else, which saves a lot of time. I guess it
would be quite easy to do this with other keying methods too.
I agree with ZL2CA that there seems to be an optimum speed for DX QRSS
contacts. I suppose it varies depending on the particular path. Too short
a dot length, and the probability of the propagation ever being good
enough is very low. Too long a dot length, and the chances of a
propagation lift lasting long enough for a QSO are small. Also, the number
of stations operating makes a difference, since propagation varies for
each location. Now that we are getting more data from monitoring beacons,
DCF39 etc, it might be possible to analyse the signal strengths
statistically to work out the optimum dot length. Of course, the other
modes we have been testing such as Jason, Wolf and so on are an attempt to
make this balance more favorable - so some DX paths may have to wait until
these are better developed before QSOs are possible. However, for the time
being, QRSS (and DFCW) do have the advantage in that they are much simpler
to get working in the typical LF amateur station, which means more people
can put them into use, and increase the chances of successful contacts.
Cheers, Jim Moritz
73 de M0BMU
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