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Re: LF: Wasilla Alaska VLF - offline

To: [email protected]
Subject: Re: LF: Wasilla Alaska VLF - offline
From: Stefan Schäfer <[email protected]>
Date: Thu, 24 Mar 2011 19:01:11 +0100
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Hi Laurence, Markus, VLF,

Hmmmm, about the 60000 windows, Paul Nicholson means.... (see a part of our emails below)

Am 19.03.2011 09:41, schrieb Paul:
Hi Stefan,

> Well, you see people are running slower and slower windows,
> such as "DFCW-60000"

There is a limit set by the variability of the path length.

For example, see

 http://abelian.org/vlf/tmp/110319a.gif

This shows the absolute phase of NAA at 24kHz over a great
circle distance of 4672km.   The graph spans 5 and a bit days.
During the day the phase advances because the D-layer height
falls from about 90km to 70km.   The pattern repeats each day
with the night-time phase (path length) pretty much the same
each night, but the daytime path varies.

The path change between day and night is almost a complete
cycle at 24kHz, so we might expect 100 to 120 degrees at 9kHz.

The value of a long coherent integration will be significantly
reduced if the phase changes by more than 30 or 40 deg.
If the phase changes by more than 90 deg, a long integration
will be worse than a shorter one.

Maybe "60000" is better anyway, as seen between DJ8WX or OE5ODL and TF3HZ. Anyway i would start with a faster mode and go for a slower, if nothing is visible. It's your dicision, Laurence :-)

73, Stefan/DK7FC



Am 24.03.2011 11:40, schrieb Markus Vester:
Hi Laurence,
 
if I had only one to choose from, I'd definitely opt for the slowest "60000" window at 47 uHz. Depending on antenna orientation, this would definitely give Scott a chance, or perhaps one of us over here. Would an onnidirectional E-field work as well for you as the RX loops?
 
Running the second FFT for the Alphas nearly doubles the CPU load, so you may want to skip that.
 
Thanks for the great work!
 
Best 73, 
Markus

-----Ursprüngliche Mitteilung-----
Von: Laurence KL7UK <[email protected]>
An: [email protected]
Verschickt: Mi., 23. Mrz. 2011, 15:34
Thema: RE: LF: Wasilla Alaska VLF - offline

VLF pre Eu dawn signals are way down from mid winter Stefan, but that signature increase on DHO38 signal between 0500 and 0700Z is still there. Looks to me like a mid winter opportunity only on this 2 x Auroral oval path at this range, but I could be mistaken. The loop is tensioned from movement by an ice screw in the lake and given the increasing temps Im sure it will come dislodged sooner than later - the other side is tensioned to a Birch tree so I dont think it will move. If Scott warms up his #2 Ill have to get someone to turn the array as hes in a Cosine null at the moment.
 
Ill take a look at the processor and see what gives but welcome any direction on speeds/fft longterm so I can leave one or two screens up longer term without frying the proc..
 
Not sure if Ill be in the same location by next winter :-(( Your going to have to work out how to get an antennae up and stable in the latter part of the of the Eu night for this path to work me thinks :-)))
 
Cheers
Laurence KL7UK, Wasilla Alaska  remote op'd from /5 Oklahoma
 

Date: Wed, 23 Mar 2011 02:24:25 +0100
From: [email protected]
To: [email protected]
Subject: Re: LF: Wasilla Alaska VLF - offline

Hello Laurence,

No hope for the end of the season? Maybe you are right, unfortunately. But you'll come back in the next season, isn't it? :-) Or maybe just reducing to wideband and 6000 or so? A pity...
But thanks for the service and the intersting location to watch and sharing the optimism!!
Maybe we'll see what can be done in Greenland, that's a next step into your direction, about...

73 and good luck,

Stefan/ EI/DK7FC
 
 
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