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 v085eg5f014772 for ; Sun, 8 Jan 2017 06:40:43 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cQ65f-0006WK-I1 for rs_out_1@blacksheep.org; Sun, 08 Jan 2017 05:32:23 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cQ65e-0006WB-Dy for rsgb_lf_group@blacksheep.org; Sun, 08 Jan 2017 05:32:22 +0000 Received: from resqmta-ch2-07v.sys.comcast.net ([2001:558:fe21:29:69:252:207:39]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cQ65Z-00074k-SO for rsgb_lf_group@blacksheep.org; Sun, 08 Jan 2017 05:32:21 +0000 Received: from resomta-ch2-17v.sys.comcast.net ([69.252.207.113]) by resqmta-ch2-07v.sys.comcast.net with SMTP id Q65Wcj5sIj8tqQ65Wc0AKR; Sun, 08 Jan 2017 05:32:14 +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=1483853534; bh=EcloZ2QbFbIGxRJmxY0fSNAZAoYvIT6irSGefnBZkss=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=eHERIEz5P+jm9/kDRbQkxGrM5aHsggfUj5HkGjXkxfwfLF6Ixce3EK6/PrtqA34yv Fjg/RQF+OsWPRwSOvNFDd5fc1H45q8iXl73HsDx5TxdHxeuy2MOun9ErFqAs9UKIPl Y2SswZtc029x4hPKEUI1EmVYNfbapyJXLQOJCO5IVdyNiM7U30CMqM7tIP4iHQMxQD MsfC55bNeY6AT3bCfeVOG7K4UbGu4o2fe28dIjFCrshdlw18jqP8UiWY6YM0KRBkb2 fMIUTha7utHPMWPYGGP61ASKyMI2INykR1Va30WTFySNmta7OylpZikDwxf7lo7/a4 PNU6c0APEyqTQ== Received: from Owner ([IPv6:2601:141:0:bec5:c047:557f:d029:2a55]) by resomta-ch2-17v.sys.comcast.net with SMTP id Q65UcWGgwmqJQQ65Vcvn5V; Sun, 08 Jan 2017 05:32:13 +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: Sun, 8 Jan 2017 00:32:09 -0500 Message-ID: <083b01d26970$8f0fb2b0$ad2f1810$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQHRhrWNJyxyDm/RcmgHwLSrpxM9jAJ5P2AlAmcy39AB+99K5AJVTiwNAugb3cMCbkK8eQK6McJ/AfteL5wB5JqacgMqFqa/Aq405s4CN15atQKUZ/i0Ai8HECcBJpNhxwGnPLWfoAmb9DA= Content-Language: en-us X-CMAE-Envelope: MS4wfNXWF817pV0+POQ698OL3J0lbQsbYF1yx1vJnmw7ZV7VjRFe556qgEU2bzTmpPtcqZPL5txZqhhURz6iW3Vi8xYuRKabljeGBXP/uACtLe6DX4yZ6VI2 Ye9D4bfVO06QbzRnzcmxoxMbX2A91qEHTyI= X-Scan-Signature: 61bef6b4a633d435cac5ff7820137883 Subject: RE: VLF: Back on 5.17 kHz / 58 km... Content-Type: multipart/alternative; boundary="----=_NextPart_000_083C_01D26946.A63C1BB0" 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: 10145 This is a multipart message in MIME format. ------=_NextPart_000_083C_01D26946.A63C1BB0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Stefan, =20 Also regarding: =E2=80=9C VLF propagation graphs = https://dl.dropboxusercontent.com/u/19882028/VLF/fig_02_25a.png = =E2=80=9D and the degree to which natural noise (and therefore indirectly SNR) = correlates with Figure 2-25 (from link above); attached is a reasonable = plot of natural noise, and a NASA plot of the lightning spectrum at = (arguably) the near/far field boundary; the spectrum of lightning is = relatively flat (+/-3.5dB) from 1 kHz to 10 kHz. =20 Comparing the Natural Noise Colorado Winter 1200-1600 (local time) plot = with: Fig. 2-25 3000 n.m., 2000 n.m., or even 1000 n.m*.: Figure 2-25 appears to show a far greater difference between 4kHz and = 10kHz signal strength than the natural noise plot shows between 4 kHz = and 10 kHz, even after subtracting 3.5dB for lightning at 10kHz (per = NASA spectrum), and (unreasonably*) using 1000 n.m. as the = signal-strength-weighted nominal distance of global lightning from = Colorado at 3dB/1000km, 1200-1600 local time in winter. =20 * (one might expect the signal-strength-weighted average distance of = Colorado winter daytime natural noise sources to be more than 2000 = nautical miles; at 3dB/1000km I would guess closer to 3000 nautical = miles for signal-strength-weighted average distance of Colorado winter = daytime natural noise sources) =20 Figure 2-25 (analytical method) shows signal strength at 3 kHz as 16dB = lower than at 7kHz, for TX-RX separation 1000km. Numerical simulations show signal strength at 3 kHz as roughly 20dB = lower than at 7kHz, for TX-RX separation 1000km. Natural noise data seems to suggest less than a 4dB difference between 3 = kHz and 7 kHz signal strength (compare to 16-20dB for analytical and = numerical methods above, and compare also with a 20dB difference in = Figure 2-25 using 2000 n.m. as the signal-strength-weighted nominal = distance of global lightning from Colorado at 3dB/1000km, 1200-1600 = local time in winter). A 35dB discrepancy between natural noise data and Figure 2-25 is seen = for 3kHz vs. 10kHz. =20 Which raises an interesting question that seems to relate to your = experiments: Given that discrepancies between the natural noise plot and the above = numerical/analytical solutions seem to be in the 16dB to 35dB range, and = given that experimental validation of the analytical (Figure 2-25) and = numerical (LWPC, FDTD etc) solutions is comparatively thin in the 3kHz = to 10kHz range, which of the two following categories might be in = substantial error: (1) natural noise extrapolation; or (2) = numerical/analytical methods? (or both?) I wonder if your experiments in the 2.97 kHz to 6.97 kHz range might = eventually reveal the answer to questions about the validity of = computational and analytical methods in that range. =20 =20 73, =20 Jim AA5BW =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_083C_01D26946.A63C1BB0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Stefan,

 

Also = regarding: =E2=80=9C VLF propagation graphs = https://dl.dropboxusercontent.com/u/19882028/VLF/fig_02_25a.png = =E2=80=9D

and the degree to which = natural noise (and therefore indirectly SNR) correlates with Figure 2-25 = (from link above); attached is a reasonable plot of natural noise, and a = NASA plot of the lightning spectrum at (arguably) the near/far field = boundary; the spectrum of lightning is relatively flat (+/-3.5dB) from 1 = kHz to 10 kHz.

 

Comparing = the Natural Noise Colorado Winter 1200-1600 (local time) plot with: = =C2=A0Fig. 2-25 3000 n.m., 2000 n.m., or even 1000 = n.m*.:

Figure 2-25 appears to show a = far greater difference between 4kHz and 10kHz signal strength than the = natural noise plot shows between 4 kHz and 10 kHz, even after = subtracting 3.5dB for lightning at 10kHz (per NASA spectrum), and = (unreasonably*) using 1000 n.m. as the signal-strength-weighted nominal = distance of global lightning from Colorado at 3dB/1000km, 1200-1600 = local time in winter.

 

* (one might expect = the signal-strength-weighted average distance of Colorado winter daytime = natural noise sources to be more than 2000 nautical miles; at 3dB/1000km = I would guess closer to 3000 nautical miles for signal-strength-weighted = average distance of Colorado winter daytime natural noise = sources)

 

Figure 2-25 (analytical method) shows signal strength = at 3 kHz as 16dB lower than at 7kHz, for TX-RX separation = 1000km.

Numerical simulations show = signal strength at 3 kHz as roughly 20dB lower than at 7kHz, for TX-RX = separation 1000km.

Natural noise data = seems to suggest less than a 4dB difference between 3 kHz and 7 kHz = =C2=A0signal strength (compare to 16-20dB for analytical and numerical = methods above, and compare also with a 20dB difference in Figure 2-25 = using 2000 n.m. as the signal-strength-weighted nominal distance of = global lightning from Colorado at 3dB/1000km, 1200-1600 local time in = winter).

A 35dB discrepancy between = natural noise data and Figure 2-25 is seen for 3kHz vs. = 10kHz.

 

Which raises an interesting question that seems to = relate to your experiments:

Given = that discrepancies between the natural noise plot and the above = numerical/analytical solutions seem to be in the 16dB to 35dB range, and = given that experimental validation of the analytical (Figure 2-25) and = numerical (LWPC, FDTD etc) solutions is comparatively thin in the 3kHz = to 10kHz range, which of the two following categories might be in = substantial error: (1) natural noise extrapolation; or (2) = numerical/analytical methods? (or both?)

I wonder if your = experiments in the 2.97 kHz to 6.97 kHz range might eventually reveal = the answer to questions about the validity of computational and = analytical methods in that range. =C2=A0

 

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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