Jim and the others who have commented - Wonderful, a great start to a
discussion that is needed at this time of year.
I offer that there are two, as I see it, distinct directions we are moving
to, the first is the use of DFT processes for detecting power in smaller and
smaller buckets (read as longer and longer information bits) and secondly
those who are into using information coding to decrease the time for the
transfer of information at the expense of needing a higher level of signal.
The later is what I consider to be the more tranditional mode of amateur
radio operating.
Jim's three step "wish list" is an excellent documentation of the second
mode, a more traditional orientation, of item two above. I wish those who
wish to focus on what I call the second mode well, and good luck going down
that road - I however will not be with you in that area of focus for next
year.
For the rest of the 2001 spring season I am available to run long duration
90 second per bit QSO attempts or to have a special session of transmitting
WOLF data if there is any interest in Europe in having such a test session.
WOLF is extremely difficult for me to send, the I/O implementation choosen
by Stewart when mixed with my situation here makes if very difficult - but
if there is interest I am available to run a couple of overnight tests
before the end of this season. I have loaded 18 hours of WOLF in one file,
in 25 minute segments, thank goodness for 30 gigabyte hard drives! I will
have to build up some hardware and do a fair amount of software to make WOLF
work from here - if the interest is present I will do it. The operative
words here are to set a time period and a reasonable level of participation
from Europe.
My work going forward from here will focus on extream weak signal detection
which continues with the goals I set here when I came to the LF community
some 18 months ago. My focus will now shift to Time and Frequency coherency
to not worse than a part or two in 10-11th. I now have GPS controlled
systems at both my home and the remote site, they are not yet complete but
they exist and will be completly functional by the fall.
The status of LF operation from Canada remains tenuous. The TransAtlantic
II project that was the basis of Canadian participation on LF has been
eclipsed from bordering on believability and achievability a year ago to
common practice in so short a time as to place in question much of the
"common wisdom" of the day. A plan for an LF allocation in Canada is before
our regulatory authority, the issue is - will enough time and resources be
available to do the work of authorizing general use of the LF band be
available in the near future?
The next issue is how many amateurs will build the systems and learn the
tricks to have an active LF community - there will be at least a year of
growth needed. With just three transmitting stations in Canada now we have
seen the limits of LF paticipation, aural only operation only by Jack,
VE1ZZ, and severly hampered (foliage challenged) LF operation by Mitch,
VE3OT and my own setup here in eastern Ontario. The situation of an LF
allocation in the United States is certainly not understood by myself - but
it can be said there is a community waiting for the opportunity to make use
of an LF allocation, but at the moment there is no certainty of
participation and this community will need growth time as well.
This being said, there is also some opportunity in the information coding
area. WOLF uses an internal synchronization process, very costly in
information bits. There are opportunities in Time Coherency as well as the
Turbo Product Codes that are achieving very high levels of performance
approaching the Shannon limit. (By the way Dr. Shannon passed away only a
month ago I learned in yesterday's newspaper). I personally want very much
to understand these coding processes and demodulation/modulation methods
enough to write my own code and experiment with them on the air, this is the
only way I will return to the information coding area of operation that I
mentioned above.
The current operational status from here is that I continue to see many
trace level weak signals from Europe almost every night. Many of them are
using bit rates that result is complete smearing here and are not readable
at all.
I have tested the 7 level FSK coding on 160M and as well on 20 Meters
(hiding in amongst the DX Beacons on 14100 kHz - they are spread out over
about 150 Hz - terrible waste of spectrum Hi). I do not recommend this work
go further, there is far greater value in the information coding mentioned
above and it is important to focus our efforts in order to make meaningful
progress.
I have no idea why but I have still not seen a single recognizable DFCW
signal on this side of the Atlantic.
The two different directions that I mentioned at the start of this memo, DFT
with longer and longer bits, and the use of information coding to increase
the signalling rate are I suggest critical to the evolution of LF. I ask
each of you to consider and comment on this segmentation and what you see as
your participation in the "speaking slowly" mode of operation. I am keen to
find others to work with in this area of extremely weak signal
communications. I encourage others who might wish to focus on really really
weak signal work to contact me directly.
Larry
VA3LK
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