Re: LF: Best results so far from Germany to Tasmania - Opera correlation?

[Markus Vester <markusvester@aol.com>]

Graham,

 

for a phase-coherent Op-32 transmission, the limit for correlation detection is about 21 dB continuous-carrier SNR in 0.5 mHz. This would scale to 7.5 dB in Edgar's noise bandwidth (11 mHz). Assuming he actually got about 12 dB (best half-hour average), there would be about 4 dB margin. But we wouldn't then claim that as a "first positive ID", as Stefan's callsign has already been pretty much perfectly readable in DFCW.

 

The preliminary Opera deep search version that Chris and I are currently running can be found on

 df6nm.bplaced.net/opera/opds2h4.zip

It is using data export from a dedicated SpecLab instance. The software seems to be running stable so far, but it will definitely require a couple more bugfixes and some explanations before it can be considered fit for general use.

 

Best 73,

Markus (DF6NM)

 

From: Graham

Sent: Wednesday, April 10, 2013 1:18 AM

To: rsgb_lf_group@blacksheep.org

Subject: Re: LF: Best results so far from Germany to Tasmania

 ''within easy reach of an Opera-32 correlation detection''

 

... That  could  also  mean  a  slightly  less  powerful , may be  10 dB  signal, originating  from a  similar  location ,  over  the  same  path  , may  provide a  OP32  correlation  detection  and be the  first   positive call sign  ID  EU>VK  ... ?

 

G :-,)

 

 

From: Markus Vester

Sent: Tuesday, April 09, 2013 7:49 PM

To: rsgb_lf_group@blacksheep.org

Cc: Vasily Savchenko ; Edgar J Twining ; David - VK2DDI

Subject: Re: LF: Best results so far from Germany to Tasmania

Edgar, Stefan,

 

this is an outstanding result! Great to see what is possible on LF, given a good antenna, a quiet location, and patience paired with persistence.

 

Did you by chance have a look at the best SNR in the spectrum plot? The fat parts of the trace might have been 12 or even 15 dB, in a 7.5 mHz FFT. This would put it within easy reach of an Opera-32 correlation detection, and possibly even close to a WSPR-15 decode.

 

Alan, I assume that DST would affect attenuation globally, without preference for one direction or another. Or could an eastern path be better during one night, versus westward in another?

 

Best 73,

Markus (DF6NM)

 

From: Stefan Schäfer

Sent: Tuesday, April 09, 2013 2:09 PM

To: rsgb_lf_group@blacksheep.org

Cc: Vasily Savchenko ; Edgar J Twining ; David - VK2DDI

Subject: LF: Best results so far from Germany to Tasmania

LF,

Last evening there was excellent LF propagation from EU to VK. Edgar J. Twining (SWL) was watching the LF DX window for several weeks now. The season on that path in spring (EU) 2013 was very poor and we already thought that the season is over. However yesterday the path was open for a exceptional long time and the S/N was very good! Transmissions were done in DFCW-180. I've been on air for several days now and such a result is most probably possible for 1 time in the year or maybe 2 years.

These are the results:
My signal: https://dl.dropbox.com/u/19882028/LF/DK7FC%20WR%20ver%20spectrum%20-18.PNG
DCF39: https://dl.dropbox.com/u/19882028/LF/DCF39%20WR%20ver%20spectrum%20-14.PNG
DCF39 plot: https://dl.dropbox.com/u/19882028/LF/DCF39%20WR%20ver%20plot%202013-04-08%2021-30.jpg

The path is 16806 km, http://no.nonsense.ee/qthmap/?qth=QE37PD&from=jn49ik00wd

It shows once again that it is always worth to transmit and to receive/watch for exceptional conds(x) on the bands!

Many thanks to Edgar for his continuous patience and interest to receive on 137 kHz from the other side of the world!

73, Stefan/DK7FC