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Yes Stefan, I'm aware of you
using 180 for VK before midnight, and that's certainly a good choice.
I had only entered 90 to the table to have more similar
durations.
I think that the best signals, eg. those
seen by VK2DDI and Edgar on a couple of occasions, would probably have
been detectable using Op-32 correlation. QSB won't kill the correlation as long as there is enough total
energy; eg. half of the time but 3dB more peak SNR.
Having said that, I still share your
preference for visual modes.
Best of
luck,
Markus (DF6NM)
Sent: Sunday, August 04, 2013 2:41 AM
Subject: Re: LF: DK7FC Equinox reception
Hi Markus, Edgar,
Well i think it is most promising to start with the good old DFCW-180.
If the success is clear and if there is no other station announcing RX attempts,
then we could continue to try other modes.
Markus, we're running DFCW-180 in
11 mHz, not DFCW-90. This has proved to be the best combination, at least from
my point of view.
Your table states that a detection in OP-32, using your
correlation software, would result in a clear decode if the signal is as good as
"M" copy in 11 mHz, right? What happens if there is QSB during that time? The
events of > 30 minutes without QSB are quite rare i think. It looks like i
have to use a kite antenna here on the building :-)
73,
Stefan/DK7FC
Am 03.08.2013 13:47, schrieb Markus Vester:
Hi Edgar, LF,
this looks like a great project, and it's good to
see a live grabber from VK7 again. So with that extra distance you might reach
the top three in the DX list... unless Mike, Bob, or someone else takes the
challenge and picks up Stefan in ZL ;-)
Orford - that's surely a nice location. On the
occasion of attending a conference some 15 years ago, we were lucky enough to
be able to drive around the Tasmanian east cost for a few days. We were much
impressed by the beauty of the landscape, the clear skies, and the friendly
and easygoing manner of the inhabitants.
Are Stefan and you intending to focus on DFCW
only, or try other modes as well? Attached beneath is a short table, lining up
approximate sensitivities for a few weak-signal options.
Best 73,
Markus (DF6NM)
Mode norm.SNR SNR bandw. duration
remarks
dBHz dB mHz
minutes
carrier -18 14
0.4* >30 highly significant peak in 0.4
mHz spectrum
DFCW-90 -12
6 11* 42 marginal
"M" detection in spectogram
DFCW-90
-6 12 11*
42 fully readable "O"
Opera-32
-1 8 125
33 reliable decoding by Opera
software
Opera-32 -12 21
0.5 33 correlation detection
of a coherent transmission
WSPR-15 -4
3.5 180 15
decoding by WSPRX software
WSPR-30 -7
3.5 90 30
accelerated replay to WSPR software
MFSK37
-9 14 3.3*
25 visual decode or automated peak
search
Notes:
- SNR thresholds are only
approximate.
- SNR referenced to carrier power (not average).
-
normalized SNR in 2.5 kHz can be obtained by subtracting 34 dB from dBHz.
*
noise bandwidth is 1.5 times the stated FFT bin width.
- duration to
send "DK7FC" message (19 dashes and 4 spaces).
- MFSK37 is absolute
frequency keying, sending one 5 minute dash per character.
Sent: Saturday, August 03, 2013 1:28 AM
Subject: LF: DK7FC Equinox reception
Hi,
During the last three Equinoxes I have attempted to
receive DK7FC's
signal at QE37pd, Moonah, Tasmania.
The best result
was achieved last April.
Refer to:
https://dl.dropboxusercontent.com/u/101251787/DK7FC%20reception.pdf
I
decided for next Equinox period, (20th September 2013), that I would
attempt to better the distance previously achieved.
The results
will be available on the internet.
https://dl.dropboxusercontent.com/u/101251787/testIDC.html
At
present the equipment is set-up at QE37pd, and when possible Stefan
is
running test transmissions from 19:00 to 22:00 UTC.
By the middle of
August the system is to be set-up at Orford, on the
east coast of
Tasmania, to operate until the end of September.
http://no.nonsense.ee/qthmap/?qth=QE37wk
The
frequencies of DCF39 and HGA22 signals are also being monitored to
determine the propagation.
So I invite members to participate by
monitoring the progress via the
web images.
Regards,
Edgar
Moonah, Tasmania.
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