Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HTML_MESSAGE,RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v07IHLG5012321 for ; Sat, 7 Jan 2017 19:17:22 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cPvPl-0000oO-KU for rs_out_1@blacksheep.org; Sat, 07 Jan 2017 18:08:25 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cPvPk-0000oF-Jt for rsgb_lf_group@blacksheep.org; Sat, 07 Jan 2017 18:08:24 +0000 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cPvPf-0005QU-HX for rsgb_lf_group@blacksheep.org; Sat, 07 Jan 2017 18:08:23 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 8BFF120A98 for ; Sat, 7 Jan 2017 19:08:14 +0100 (CET) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3twqCf0FdmzyQg for ; Sat, 7 Jan 2017 19:08:13 +0100 (CET) Message-ID: <58712E8D.9050207@posteo.de> Date: Sat, 07 Jan 2017 19:08:13 +0100 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <159526aa32e-1297-2d056@webprd-m96.mail.aol.com> <5867AA75.6030603@posteo.de> <5867DFA9.5020604@abelian.org> <58691D84.9030201@posteo.de> <586A8A05.5090901@posteo.de> <586AA7C5.8070802@abelian.org> <049501d26535$dee8b370$9cba1a50$@comcast.net> <586B5BAD.7@abelian.org> <586C4F2C.1010205@posteo.de> <586D6E99.6080509@posteo.de> <586F5D60.4030309@abelian.org> <586F7C4F.3090806@posteo.de> <586F8082.4060404@abelian.org> <5870097B.7080708@posteo.de> <58701056.20008@posteo.de> <587069F3.1010407@abelian.org> In-Reply-To: <587069F3.1010407@abelian.org> X-Scan-Signature: cd79e98bb57cf38a756c15469b5a993e Subject: Re: VLF: Back on 5.17 kHz / 58 km... Content-Type: multipart/alternative; boundary="------------060909070604000505000404" X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: A X-Keywords: X-UID: 10135 This is a multi-part message in MIME format. --------------060909070604000505000404 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Thanks Paul (and Renato and Wolf!), very well! The carrier on 5170.001250 Hz is still on the air and will run until 18 UTC. Since it appears that you and Jacek are the only ones trying to receive my EbNaut, i'll stay at 16K25A, just to use the better code gain. And since the last ~ 24 hour experiment was running so well, let's try 48 hours! Maybe it leads to a 30 0 30 0 phase pattern: *f = 5170.000000 Hz Start time: 07.Jan.2017 20:00:00 UTC Symbol length: 64 s Characters: 20 CRC 16 Coding 16K25A Duration: 45h, 30m, 40s Antenna current: ~ 225 mA* The first time i used your calculator (http://abelian.org/ebnaut/calc.php?sndb=-63&snbws=2500&snmps=&code=16K25&sp=64&crc=16&nc=20&submit=Calculate ) to chosse the number of characters and the symbol length BEFORE the transmission :-) With your given RAM, how many characters can you decode in 16K25A? And how long does the decode process take then? These 2 day long transmissions mostly failed on 6.47 kHz, or gave poor results. Stacked single day transmissions were a better choice. For a 50 or 75 character message on 5170 Hz we may have to use the same technique. I'm often thinking about the old VLF propagation graphs https://dl.dropboxusercontent.com/u/19882028/VLF/fig_02_25a.png (what was the original paper where it comes from?) which make more and more sense to me! On 5170 Hz we already see a real advantage of lower QRN relative to 8270 Hz or 6470 Hz. According to the graphs, the optimum frequency should be arround 4 kHz because the QRN from far away is attenuated much more whereas the poor propagation on that frequency is not so much expressed for 'short' (1000 km) distances. And BTW, 4 is a very nice number, isn't it!? Sooner or later someone has to do something near 4 kHz! I would be curious to see how this band (e.g. 4270 Hz or 70 km!) behaves. I can imagine that it is the best choice, even in summer or especially in summer! When looking on the todays 'wideband' window (the upper one on http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html) we can see that we are already diving below the QRN :-) 73, Stefan Am 07.01.2017 05:09, schrieb Paul Nicholson: > > Decoded '73 DK7FC' from Cumiana (Renato Romero, vlf15, 504.6km) > with constant ref phase, Eb/N0 = 0.6, S/N 16.16 dB in 11.8 uHz, > -67dB in 2.5kHz. > > Very strong at Bielefeld (Wolf Buescher, vlf6, 303.8km) > Eb/N0 11.6dB, 27.17 dB in 11.8 uHz, -56.1dB in 2.5kHz, > constant reference phase. > > > Here, improved my decode to 3.9dB when I remembered to use the > -a option which normalises the amplitude by the average noise. > > I am not seeing much day/night phase shift at any site. Some > measurements on the carrier will be the next job. > > -- > Paul Nicholson > -- > --------------060909070604000505000404 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Thanks Paul (and Renato and Wolf!), very well!

The carrier on 5170.001250 Hz is still on the air and will run until 18 UTC.

Since it appears that you and Jacek are the only ones trying to receive my EbNaut, i'll stay at 16K25A, just to use the better code gain.
And since the last ~ 24 hour experiment was running so well, let's try 48 hours! Maybe it leads to a 30 0 30 0 phase pattern:

f = 5170.000000 Hz
Start time: 07.Jan.2017   20:00:00 UTC
Symbol length: 64 s
Characters: 20
CRC 16
Coding 16K25A
Duration: 45h, 30m, 40s
Antenna current: ~ 225 mA

The first time i used your calculator (http://abelian.org/ebnaut/calc.php?sndb=-63&snbws=2500&snmps=&code=16K25&sp=64&crc=16&nc=20&submit=Calculate ) to chosse the number of characters and the symbol length BEFORE the transmission :-)

With your given RAM, how many characters can you decode in 16K25A? And how long does the decode process take then?

These 2 day long transmissions mostly failed on 6.47 kHz, or gave poor results. Stacked single day transmissions were a better choice. For a 50 or 75 character message on 5170 Hz we may have to use the same technique.

I'm often thinking about the old VLF propagation graphs https://dl.dropboxusercontent.com/u/19882028/VLF/fig_02_25a.png (what was the original paper where it comes from?) which make more and more sense to me! On 5170 Hz we already see a real advantage of lower QRN relative to 8270 Hz or 6470 Hz. According to the graphs, the optimum frequency should be arround 4 kHz because the QRN from far away is attenuated much more whereas the poor propagation on that frequency is not so much expressed for 'short' (1000 km) distances. And BTW, 4 is a very nice number, isn't it!? Sooner or later someone has to do something near 4 kHz! I would be curious to see how this band (e.g. 4270 Hz or 70 km!) behaves. I can imagine that it is the best choice, even in summer or especially in summer!
When looking on the todays 'wideband' window (the upper one on http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html) we can see that we are already diving below the QRN :-)

73, Stefan



Am 07.01.2017 05:09, schrieb Paul Nicholson:

Decoded '73 DK7FC' from Cumiana (Renato Romero, vlf15, 504.6km)
with constant ref phase, Eb/N0 = 0.6, S/N 16.16 dB in 11.8 uHz,
-67dB in 2.5kHz.

Very strong at Bielefeld (Wolf Buescher, vlf6, 303.8km)
Eb/N0 11.6dB, 27.17 dB in 11.8 uHz, -56.1dB in 2.5kHz,
constant reference phase.


Here, improved my decode to 3.9dB when I remembered to use the
-a option which normalises the amplitude by the average noise.

I am not seeing much day/night phase shift at any site.  Some
measurements on the carrier will be the next job.

--
Paul Nicholson
--

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