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=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,RCVD_IN_DNSWL_MED, SPF_PASS,T_DKIM_INVALID,T_KAM_HTML_FONT_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; 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 v082MMTF014001 for ; Sun, 8 Jan 2017 03:22:23 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cQ32o-00045r-Sm for rs_out_1@blacksheep.org; Sun, 08 Jan 2017 02:17:14 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cQ32n-00045i-Q4 for rsgb_lf_group@blacksheep.org; Sun, 08 Jan 2017 02:17:13 +0000 Received: from resqmta-ch2-06v.sys.comcast.net ([2001:558:fe21:29:69:252:207:38]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cQ32i-0006fl-IA for rsgb_lf_group@blacksheep.org; Sun, 08 Jan 2017 02:17:12 +0000 Received: from resomta-ch2-20v.sys.comcast.net ([69.252.207.116]) by resqmta-ch2-06v.sys.comcast.net with SMTP id Q32ecGDfzTERUQ32ecj1Zs; Sun, 08 Jan 2017 02:17:04 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1483841824; bh=z0Wz7XER96cL1jPYUhLahq3n+xeNeafhaj1t0D+Kq/Q=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=UTvK98APdMvZ8QDO1mXsfjZTfFhbcQsPPbMu7jdTOrsetRF6KvDzQaFdEpTymUo59 nSWj4Il3vqCXJ3/O9bcUNxSX1+whH6aLr2qghSjUk+HXIkWQNMAQiv6UvE/MTtHVGI TOJZWHAf+KNy+5P6KqnrozhqDpIGpoLx2xBEnC04QMl1h3sqMGWnt9hOmPzt1pD8mO 4Fsg30EMYfvBunKd/5egpRD4Zu+H5LHaJfmHi0Dhj4eKMUBBwjzaJJmzjwIG8yNoCG Fuh5yCMDja6SeUrRlbTdBcxwjUnZW5FXQk5cJSxmludnxzEAq/o2KbJKsjX2DNxdPv uc/cMwfx5FJyQ== Received: from Owner ([IPv6:2601:141:0:bec5:c047:557f:d029:2a55]) by resomta-ch2-20v.sys.comcast.net with SMTP id Q32dcHEsHeSQaQ32dc02NN; Sun, 08 Jan 2017 02:17:04 +0000 From: To: 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> <58712E8D.9050207@posteo.de> In-Reply-To: <58712E8D.9050207@posteo.de> Date: Sat, 7 Jan 2017 21:16:48 -0500 Message-ID: <082d01d26955$4be3e990$e3abbcb0$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQHRhrWNJyxyDm/RcmgHwLSrpxM9jAJ5P2AlAmcy39AB+99K5AJVTiwNAugb3cMCbkK8eQK6McJ/AfteL5wB5JqacgMqFqa/Aq405s4CN15atQKUZ/i0Ai8HECcBJpNhxwGnPLWfoAlYY/A= Content-Language: en-us X-CMAE-Envelope: MS4wfOvM55nwtpMkT9U+KKYqJsurwCSesT6U04fsyKu02lN8KdmQkoGzcievWhbL8V47oB1xZLxCms8NCN7vmc/ZE+bYRKWu7dtgkO5WdVJaCqypCRKJ7f0J 8zcl4XlDuC3EPgolDioGz0zgbq+IKwNPf1I= X-Scan-Signature: 25586c7917467b5c110472bf48f6f4f3 Subject: RE: VLF: Back on 5.17 kHz / 58 km... Content-Type: multipart/alternative; boundary="----=_NextPart_000_082E_01D2692B.630DE190" 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: X-Keywords: X-UID: 10144 This is a multipart message in MIME format. ------=_NextPart_000_082E_01D2692B.630DE190 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Stefan, =20 Your message included:=20 =E2=80=9C=E2=80=A6 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=E2=80=A6=E2=80=9D =20 The figure (Fig 2-25) comes from: =E2=80=9CNaval Shore Electronics = Criteria: VLF, LF, and MF Communication Systems=E2=80=9D - NAVELEX = 0101,113 - August 1972 http://www.navy-radio.com/manuals/shore-vlf.htm The above link downloads as 9 separate chapters totaling 52.5MB =20 Beware a 24.2MB copy of the same manual elsewhere on the web; it has = some blur which by Murphy=E2=80=99s Law will interfere only with reading = of the plots important to you. =20 The manual states that the data from which Figure 2-25 is generated = comes from the first formula in Section 2.3 of the same manual = (paragraph beginning with =E2=80=9CWait=E2=80=99s formula for the = vertical electric field strength=E2=80=A6 is given by:=E2=80=9D); and = the attenuation factor chosen for Figure 2-25 comes generally from the = attenuation-factor plot in Figure 2-20 (see the two paragraphs above = Table 2-1 describing the derivation). =20 =20 Comments:=20 a) Modeling has come a long way since the manual was published in = 1972, but I very much agree with and appreciate your point that Figure = 2-25 tells a vital story (and I think that the Figure 2-25 story has = been almost lost in all of the modern modeling). I don=E2=80=99t think = that any of the Figure 2-25 story is negated by modern modeling; the = modern models generally add low-accuracy +/- variations for = time/date/lat/long etc.=20 b) It seems to me that your experiments are importantly refining = and adding to the Figure 2-25 story; including new chapters. Very = exciting. =20 Other comments: =20 A statement in the manual above Table 2-1, referring in part to Figure = 2-25, may be misleading in one particular (but important) context. The = statement says: =E2=80=9C=E2=80=A6 noise energy at VLF/LF propagates in = the same manner (i.e. same manner as in Figure 2-25, which is for a 1kW = ERP from a vertical antenna, 80km ionosphere reflection height) and is = subject to the same attenuations as signal energy in these = spectra=E2=80=A6=E2=80=9D. =20 That statement, if extrapolated to SNR (which the manual does not do, = but which most readers would like to do), would need to be carefully = applied to assessment of SNR in any particular experiment, except = perhaps in wintertime. In wintertime at +50 degrees latitude one might = not need to be too careful in using Figure 2-25 to determine which = frequency will give best SNR for a particular distance, but in regional = thunderstorm season the application of Figure 2-25 to best frequency for = best SNR at a given TX-RX separation might be dependent on where = thunderstorms tend to concentrate regionally and how much those = thunderstorms affect the height of the ionosphere over the chosen TX-RX = path, especially for TX-RX separations between 300 km and 1000 km = (changes in ionospheric height can cause particularly large changes in = signal propagation at TX-RX separations 300km-1000km). So estimating = best frequency for best SNR from Figure 2-25 is particularly affected by = thunderstorms in the region in two ways: (1) rather flat VLF emission = spectrum of lightning and clustering of lightning at various ranges = during regional thunderstorm season (this matters even if lightning is = not in the TX-RX path); and (2) elevation of the ionospheric reflection = height by the lightning (this matters only if the lightning is alongside = or in the TX-RX path, and the effect would be enhanced by = modal-interference effects if the TX-RX path is 300km-1000km) =20 =20 Last comment: Lulu Publishing advertises a bound copy of this manual (=E2=80=9CNaval = Shore Electronics Criteria: VLF, LF, and MF Communication = Systems=E2=80=9D) with a small note: =E2=80=9C=E2=80=A6 The chapters on VLF are omitted.=E2=80=9D I thought about writing a letter of indignation but instead requested = that they add the full manual to their inventory. =20 73, =20 Jim AA5BW =20 =20 =20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of DK7FC Sent: Saturday, January 7, 2017 1:08 PM To: rsgb_lf_group@blacksheep.org Subject: Re: VLF: Back on 5.17 kHz / 58 km... =20 Thanks Paul (and Renato and Wolf!), very well!=20 The carrier on 5170.001250 Hz is still on the air and will run until 18 = UTC.=20 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 =3D 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=3D-63 = = &snbws=3D2500&snmps=3D&code=3D16K25&sp=3D64&crc=3D16&nc=3D20&submit=3DCal= culate ) 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:=20 Decoded '73 DK7FC' from Cumiana (Renato Romero, vlf15, 504.6km)=20 with constant ref phase, Eb/N0 =3D 0.6, S/N 16.16 dB in 11.8 uHz,=20 -67dB in 2.5kHz.=20 Very strong at Bielefeld (Wolf Buescher, vlf6, 303.8km)=20 Eb/N0 11.6dB, 27.17 dB in 11.8 uHz, -56.1dB in 2.5kHz,=20 constant reference phase.=20 Here, improved my decode to 3.9dB when I remembered to use the=20 -a option which normalises the amplitude by the average noise.=20 I am not seeing much day/night phase shift at any site. Some=20 measurements on the carrier will be the next job.=20 --=20 Paul Nicholson=20 --=20 ------=_NextPart_000_082E_01D2692B.630DE190 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Stefan,

 

Your message included:

=E2=80=9C=E2=80=A6 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=E2=80=A6=E2=80=9D

 

The figure = (Fig 2-25) comes from: =E2=80=9CNaval Shore Electronics Criteria: VLF, = LF, and MF Communication Systems=E2=80=9D - NAVELEX 0101,113 - August = 1972

http://www.navy-= radio.com/manuals/shore-vlf.htm

The above link downloads as 9 separate chapters = totaling 52.5MB

 

Beware a = 24.2MB copy of the same manual elsewhere on the web; it has some blur = which by Murphy=E2=80=99s Law will interfere only with reading of the = plots important to you.

 

The manual = states that the data from which Figure 2-25 is generated comes from the = first formula in Section 2.3 of the same manual (paragraph beginning = with =E2=80=9CWait=E2=80=99s formula for the vertical electric field = strength=E2=80=A6 is given by:=E2=80=9D); and the attenuation factor = chosen for Figure 2-25 comes generally from the attenuation-factor plot = in Figure 2-20 (see the two paragraphs above Table 2-1 describing the = derivation). =C2=A0

 

Comments:

a)      = Modeling has come a long way since the manual was published in 1972, = but I very much agree with and appreciate your point that Figure 2-25 = tells a vital story (and I think that the Figure 2-25 story has been = almost lost in all of the modern modeling). I don=E2=80=99t think that = any of the Figure 2-25 story is negated by modern modeling; the modern = models generally add low-accuracy +/- variations for time/date/lat/long = etc.

b)      = It seems to me that your experiments are importantly refining and = adding to the Figure 2-25 story; including new chapters. Very = exciting.

 

Other comments:

 

A statement in the manual above Table 2-1, referring in part to = Figure 2-25, may be misleading in one particular (but important) = context. The statement says: =E2=80=9C=E2=80=A6 noise energy at VLF/LF = propagates in the same manner (i.e. same manner as in Figure 2-25, which = is for a 1kW ERP from a vertical antenna, 80km ionosphere reflection = height) and is subject to the same attenuations as signal energy in = these spectra=E2=80=A6=E2=80=9D. =C2=A0=C2=A0

That statement, if extrapolated to SNR (which the manual does not do, = but which most readers would like to do), would need to be carefully = applied to assessment of SNR in any particular experiment, except = perhaps in wintertime. In wintertime at +50 degrees latitude one might = not need to be too careful in using Figure 2-25 to determine which = frequency will give best SNR for a particular distance, but in regional = thunderstorm season the application of Figure 2-25 to best frequency for = best SNR at a given TX-RX separation might be dependent on where = thunderstorms tend to concentrate regionally and how much those = thunderstorms affect the height of the ionosphere over the chosen TX-RX = path, especially for TX-RX separations between 300 km and 1000 km = (changes in ionospheric height can cause particularly large changes in = signal propagation at TX-RX separations 300km-1000km). So estimating = best frequency for best SNR from Figure 2-25 is particularly affected by = thunderstorms in the region in two ways: (1) rather flat VLF emission = spectrum of lightning and clustering of lightning at various ranges = during regional thunderstorm season (this matters even if lightning is = not in the TX-RX path); and (2) elevation of the ionospheric reflection = height by the lightning (this matters only if the lightning is alongside = or in the TX-RX path, and the effect would be enhanced by = modal-interference effects if the TX-RX path is 300km-1000km) = =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0

=C2=A0

Last comment:

Lulu Publishing advertises a bound copy of this manual = (=E2=80=9CNaval Shore Electronics Criteria: VLF, LF, and MF = Communication Systems=E2=80=9D) with a small = note:

=E2=80=9C=E2=80=A6 The chapters on VLF are = omitted.=E2=80=9D

I thought about writing a letter of indignation but instead requested = that they add the full manual to their = inventory.

 

73,

 

Jim AA5BW

 

 

 

 

From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of = DK7FC
Sent: Saturday, January 7, 2017 1:08 = PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: = VLF: Back on 5.17 kHz / 58 km...

 

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 =3D 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=3D-63&snbws=3D= 2500&snmps=3D&code=3D16K25&sp=3D64&crc=3D16&nc=3D20&a= mp;submit=3DCalculate ) 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.ht= ml) 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 =3D = 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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