Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

RE: LF: ebnaut 5170 - decode nr Moscow

To: <[email protected]>
Subject: RE: LF: ebnaut 5170 - decode nr Moscow
From: <[email protected]>
Date: Wed, 25 Oct 2017 19:35:10 -0400
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1508974514; bh=MPOKMTXfOYeWzOIHc2fu4ErQf2SuiWzbZkyhfu9QfFM=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=PN8ZonrMB/RPyQfqv70FHqZFs6cqAk0VU12XKr+p2gTI1k6T6oYKiRXi9jLEXxyfP dQvKeof6em4Mu3aM+2/tryVio+7nbGhmPJjgP20qnEeXS5l6MelWMqZNQB8Z56N9rS 2FNRbozU7eWbiBXyp789GrwB3Dj6XaBk8Bw1YYX/nHfC7by0JYuwYhUR8XHEaIQsBP lzbDcrQm5ueOdm5TEuS/wcXvvme3z5tpMmFWF4qWT+/ugo6gXPCDLgqGnulU/NH4GJ 4x1P4Ibr5swHNDvRwCn6AqPmapVQPA7Yr2PgRDoAa2Ov5Py/e7m3dcvh80tS/WzsAz 3fUcFEOP2woqg==
In-reply-to: <[email protected]>
References: <CAGZ2MyavuG-8vFsbJTg5gdrCQAq6o8msgN+EdRqn+Gb_9M2EMQ@mail.gmail.com> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Thread-index: AQILL4BYY645Esf2QIsymayaHuZIzAMp18GgomwXRAA=
Stefan,

The attached doesn't show noise vs frequency vs season/distance very well, but 
examples include:
a)
Colorado data seem to suggest less reduction in noise as frequency decreases 
from 9k Hz to 3 kHz, for more-distant lightning (this by comparing seasonal and 
time-of-day Colorado data and knowing that Colorado and Florida are important 
sources)
b)
In contrast to (a) above, comparing California 0800-1200 data (wherein even 
summer noise may be nominally from 2000 km away) to Colorado Summer 0800-1200 
data (wherein late-morning local lightning probably dominates lightning from 
elsewhere), the distant-lightning case (California) shows a considerably 
greater reduction in noise as frequency decreases from 9k Hz to 3 kHz. 

Neither of the above clearly shows noise vs frequency vs season/distance, but 
perhaps they suggest that many variables are involved.

Also notice that Colorado Spring 0800-1200 noise minimum is uniquely shifted to 
6 kHz, with only a few dB difference from the 10 kHz peak.  Maxwell and Stone 
noted that as a curiosity.

Once again I'm guessing that your upcoming experiments may provide some of the 
most relevant data available.

73,

Jim AA5BW

  

-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of DK7FC
Sent: Wednesday, October 25, 2017 4:55 PM
To: [email protected]
Subject: Re: LF: ebnaut 5170 - decode nr Moscow

Hi Alex, Paul, VLF,

I found that the fascination risis with the square of the wavelength!

My congrats again to your ufb VLF RX and thank you for your effeorts. We are 
very successful.

I never expected that we can transfer messages on 5170 Hz over that path with 
such a rate. Now we have some important data: We can expect 6 dB in
23 uHz during an average quiet night. So now we can calculate how many days 
must be expected for a longer message, like we did on 6470 Hz. I would like to 
try a 12 character message soon. It takes just 2 weeks or so :-)

Paul, maybe you are interested in wav files for reprocessing. I attached the 
23th and 20th...24th(weighted). The size is very small...

For the 23th i got an even better result with a time offset of 1754 seconds.

My ERP on 5170 Hz is 2 dB lower than on 6470 Hz.  But the SNR we observe seems 
not to differ much from that on 6470 Hz. The opposite of what all the curves 
predict!!!!!!
So what will happen arround 4 kHz???!!! Will we be able to send messages over 
that respectable distance? I bet!
 From 4 kHz it is not so far until we reach 2.97 kHz!! That's my dream for this 
season, 2 characters on 2.97 kHz over that path!

We were focused on that one graph showing VLF propagation as a function of the 
frequency, for different distances (and constant ERP!). But the y axis shows 
field strength and not SNR! What is when most of the noise comes from far away 
(> 4000 km), which is the case in winter on our path!? Then the noise will drop 
stronger than the signal? This first experiment seems to be a first sign for 
that assumption. So what happens on 4.47 kHz relative to 5.17 kHz? The ERP will 
drop by just 1.2 dB. But the noise may fall much stronger!! We will check that 
too :-) And on
2.97 kHz, relative to 5.17 kHz: Just 5 dB less ERP and maybe a much better 
noise reduction!

73, Stefan



Am 25.10.2017 18:23, schrieb Alex K:
> Hello VLF, Stefan
> I'm glad to report about sucsessfull decode of 1-char ebnaut message 
> sended on 5170.1 Hz 20,22,23 and 24 October.
> Message was decoded by weighted stacking, unweighted stacking and from
> 23 okt file only. Other files give very poor decode with many false 
> decodes or only false decodes.
> In attacment we can see best decode from weighted stacking.
> Also all ebnaut-files is available here: 
> http://rn3aus.narod.ru/5170.zip My VY congratulations to Stefan! Ab
>
> ebnaut-rx V0.7a
> input file sum.wav
> sample rate 0.342935 per second
> rx frequency 5170.1
> file start time 2017-10-24 15:30:58.390 polynomial 8K19A crc size 6 
> number of chars 1 block size 12 symbol period 180.000 number of 
> symbols 240 list length 20 start offset 1754.000 freq offset 0.000000 
> cores 1 skipped 1755.434703 seconds to start initial reference phase 
> -27.5
> ---------------------------------------------
> found =
> list rank 0
> reference phase    0    0    0    0
> carrier S/N 12.10 dB in 23.1 uHz, -34.26 dB in 1Hz, -68.24 dB in 
> 2.5kHz carrier Es/N0 -11.70 dB carrier Eb/N0 4.54 dB info bit period 
> 7578.95 seconds symbol error rate 79/240 = 32.917 %
> Es/N0 from symbol errors -10.0 dB
> Eb/N0 from symbol errors 6.2 dB
> Shannon capacity 1.9 bits/hour
> Shannon efficiency 25.2 %
> symbols file sum-symbols.csv
> elapsed 2 seconds
>
>

Attachment: Natural Noise Floor including Maxwell Stone AJ6LS -- Plot Only - 53 kB....pdf
Description: Adobe PDF document

<Prev in Thread] Current Thread [Next in Thread>