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Re: LF: 8270 Hz traces again! AK

To: [email protected]
Subject: Re: LF: 8270 Hz traces again! AK
From: DK7FC <[email protected]>
Date: Tue, 08 Dec 2015 16:41:10 +0100
In-reply-to: <[email protected]>
References: <[email protected]>
Reply-to: [email protected]
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Hi Uwe,

My active VLF antenna inside a plastic tube was hanging down since a few days, see the spectrograms. Now i repaired that and the signal levels are back to their normal level.
You are coming nicely in 424 uHz! Looking forward to an incoming trace now.
I'm thinking about playing on VLF a bit. Maybe we can do a VLF QSO some day.

73, Stefan

Am 08.12.2015 12:44, schrieb [email protected]:

carrier on the air.
the message starts at 18:00:00
wedj8wx
 
Von: [email protected]
Gesendet: 03.12.2015 13:45
An: <[email protected]>
Betreff: AW: Re: AW: LF: 8270 Hz traces again! AK
 

hope the transmission can stay 24 hours a day on the air soon.
so your analysis may show less phase destructions at night hours.
Uwe/dj8wx

 
Von: Paul Nicholson <[email protected]>
Gesendet: 01.12.2015 23:27
An: <[email protected]>
Betreff: Re: AW: LF: 8270 Hz traces again! AK
 

Uwe wrote:

> transmission CL because of heavy rain

Got a good carrier from you

http://abelian.org/vlf/fbins.shtml#p=1448996400&b=090&s=sp

and this decoded easily in EbNaut using 10 second symbols,
eg 8K19A 2 characters,

found rank 7: ** ps [ 2 30 30 30 30]
re-encode 140/368 ber 3.80e-01 Es/N0=-13.3 Eb/N0=1.6

Carrier decodes as a series of '*' characters which is handy
for testing. Using the carrier I can try a range of message
lengths and symbol periods.

Using about an hour of carrier from 17:00 I got

8K19A, 8 seconds, 3 chars: Eb/N0=-0.2
16K21A, 4 seconds, 3 chars: Eb/N0=1.0
8K23A, 7 seconds, 4 chars: no decode

I grabbed 3 hours of carrier, 15:00 to 18:00 and played around
with that but couldn't get a decode from it. It's a bad time
of day due to the terminator passage, the phase goes all over
the place so I'm not too surprised.

Tested the carrier 15:00 to 16:00 and got

8K23A, 7 seconds, 4 chars: -0.8 dB (BER 38.9% rank 679)
16K21A, 3.4 seconds, 5 chars: -0.7 dB (BER 41.4% rank 3200)

I couldn't get anything from the 90 minutes 15:00 to 16:30.

--
Paul Nicholson
--
 
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