Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id wBKMUvos020884 for ; Thu, 20 Dec 2018 23:31:05 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ga6ms-0000S9-CC for rs_out_1@blacksheep.org; Thu, 20 Dec 2018 22:27:26 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ga6mq-0000S0-Cx for rsgb_lf_group@blacksheep.org; Thu, 20 Dec 2018 22:27:24 +0000 Received: from resqmta-ch2-01v.sys.comcast.net ([2001:558:fe21:29:69:252:207:33]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1ga6mn-0000zK-5Q for rsgb_lf_group@blacksheep.org; Thu, 20 Dec 2018 22:27:23 +0000 Received: from resomta-ch2-14v.sys.comcast.net ([69.252.207.110]) by resqmta-ch2-01v.sys.comcast.net with ESMTP id a1f8gYdbXoE06a6mkgzDvy; Thu, 20 Dec 2018 22:27:18 +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=1545344838; bh=paVLYCjLMQ2oxVdQSwSnKAwBeEBI03xSEOJ2BaMkwHU=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=YKJPqJvZa5lK0caP8XdkllyIPDEKWh+HGfDPSiP0AdirsQC9MFoslOoz0lwrONu2J 1k36Z5iA7hZ3uAnhZRUxz908IMolFHSyMx3TrYf08mDS/4ZCAyVDkxalfalj3v+bN0 v2eS/JHF5FmETd3OGCOwf/dvC7FczKQYrSsZQi7wYiv3zhZP3rDm+cvHdAPByXOf6E gMZ1cZ4Ins0COqr+Uvg7z94VYAcQ0X3h7GJ6mAxiAwYpcsHfFiKaA0iHw49rVdEA7D /ZBwc/9qm5nXPD0Ccu2LGscWKDoBMf+b6FTUpJ/6dmqt32uAnRJ29Z8ikprEG8220g kN205gJekUCTg== Received: from Owner ([IPv6:2601:140:8500:7f9f:c1f8:e6e9:9580:7785]) by resomta-ch2-14v.sys.comcast.net with ESMTPA id a6migcznBic2ua6mjgrPzL; Thu, 20 Dec 2018 22:27:17 +0000 X-Xfinity-VMeta: sc=0;st=legit From: To: References: <5BE0C0CE.10008@posteo.de> <5BE19D5E.7000408@posteo.de> <5BF7C6B4.8090104@posteo.de> <5BFCFF7D.8090006@posteo.de> <5C1BDAA0.70409@posteo.de> In-Reply-To: <5C1BDAA0.70409@posteo.de> Date: Thu, 20 Dec 2018 17:26:03 -0500 Message-ID: <008301d498b3$29a600e0$7cf202a0$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Content-Language: en-us Thread-Index: AQHgdirWgwX/aRwQiLXxXwMjbK+3sQL/2MgsAie3hBsBnybMcwKl7s0lpSUDe/A= X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hello Stefan, Very nice signal at 80 Hz (seen in your grabber plot). Your DFCW-5400 plot seems to indicate about 25dB-30dB SNR during a quiet period around 02:30 on 27 November; does 25-30dB SNR in the quietest period 27 Nov - 29 Nov sound approximately correct (in oth [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2001:558:fe21:29:69:252:207:33 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_KAM_HTML_FONT_INVALID BODY: Test for Invalidly Named or Formatted Colors in HTML 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 77f21f6e11988daa90d969af432362a6 Subject: RE: SLF: EbNaut @ 80 Hz Content-Type: multipart/alternative; boundary="----=_NextPart_000_0084_01D49889.40CFF8E0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_30_40,HTML_MESSAGE, NO_REAL_NAME autolearn=no version=2.63 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 This is a multipart message in MIME format. ------=_NextPart_000_0084_01D49889.40CFF8E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hello Stefan, Very nice signal at 80 Hz (seen in your grabber plot). Your DFCW-5400 plot seems to indicate about 25dB-30dB SNR during a quiet period around 02:30 on 27 November; does 25-30dB SNR in the quietest period 27 Nov - 29 Nov sound approximately correct (in other words am I interpreting the plot correctly)? Is 5400 is equal to or similar to the number of seconds of integration? It is exciting to read that you are headed toward 23 Hz. I had guessed that natural noise at 23 Hz might be ~ 20 dB higher than at 9 kHz, and that an impulse blanker (lightning noise blanker) might not work so well at 27 Hz because the long tails of the sferics overlap. Natural signals ("noise") at 1 Hz and below can have long spatial correlation distances (many hundreds of km) which would enable noise reduction by subtraction of digitized signal from a distant receiver (much farther from the transmitter), from the digitized signal of the local receiver. I don't know if the spatial correlation lengths are anywhere near as long at 23 Hz as at 1 Hz (23 Hz has a greater ratio of sferic noise to magnetotelluric noise), but still wonder if you could subtract raw data from another receiver perhaps 170 - 230 km away to cancel 23 Hz noise captured by your local receiver? 73, Jim AA5BW From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of DK7FC Sent: Thursday, December 20, 2018 1:09 PM To: rsgb_lf_group@blacksheep.org Subject: Re: SLF: EbNaut @ 80 Hz SLF, For the completion of this thread, here is the reprocessed spectrogram of a DFCW-5400 message at 80 Hz (attachment). It is just a small distance but anyway challenging, on the TX side as well as on the RX side. Usually i want to detect a carrier, then an EbNaut message and finally a DFCW message when visiting one of these really low bands. Next step is ELF at 23 Hz but this is even more challenging. Thus there is some delay... 73, Stefan Am 27.11.2018 09:25, schrieb DK7FC: Hi SLF, Yesterday, a 45 character EbNaut was transmitted at 80.005 Hz. It was received on my tree in 3.5 km distance. After the improvement of the RX antenna it looks like i gained about 2.5 dB SNR. It was an easy decode, the message could have been transmitted 4 times faster. Capture attached :-) 73, Stefan PS: With that SNR, a 5 character message could be transferred out to 7 km distance in less than 1 day. Am 23.11.2018 10:21, schrieb DK7FC: Dear SLF friends, A new step forward towards DC: Since yesterday 22:30 UTC i'm TXing a carrier at 80.005 Hz. That's the 3750 km band, where the far field begins at a distance of 598 km. The antenna voltage is just 5 kV and i'm getting 1.2 mA antenna current, giving an ERP of 20 fW (2E-14 W). The voltage is even higher than in my recent experiment on 270 Hz, anyway the S/N is lower, indicating that my RX lacks of sensitivity. Indeed this experiment helps to estimate the lack of sensitivity. Looks like i'm missing about 10 dB on that frequency. Anyway the signal is making the path of 3.5 km to my tree grabber, as usual shown at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html. Not a big distance but still well beyond most garden fences! The signal leaves a barely visible trace in the ZEVS window which is running at 3.8 mHz FFT bin witdh. Unfortunately ZEVS is off the air since a week or so. actually i wanted to transmit side by side with ZEVS, of course a bit deeper even. >From a quiet period at night, i calculated the SNR of a 1 hour carrier period using vlfrx-tools: carrier S/N: 16.83 dB in 277.8 uHz, -18.73 dB in 1Hz For the crazy homebrewers i'd like to share that website where i ordered the HV-transformer, http://www.hosin.de/Specials/HV-Trafo/hv-trafo.html A nightmare for all safety-fetishists! For the completeness it must be mentioned together with that page: http://kurts-werkstatt.de/hv-trafo.htm 73, Stefan ------=_NextPart_000_0084_01D49889.40CFF8E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hello Stefan,

 

Very nice signal at 80 Hz (seen in your grabber = plot).

Your DFCW-5400 plot seems to indicate about 25dB-30dB SNR during a = quiet period around 02:30 on 27 November; does 25-30dB SNR in the = quietest period 27 Nov – 29 Nov sound approximately correct (in = other words am I interpreting the plot = correctly)?

Is 5400 is equal to or similar to the number of seconds of = integration?

 

It is exciting to read that you are headed toward 23 = Hz.

I had guessed that natural noise at 23 Hz might be ~ 20 dB higher = than at 9 kHz, and that an impulse blanker (lightning noise blanker) = might not work so well at 27 Hz because the long tails of the sferics = overlap. Natural signals (“noise”) at 1 Hz and below can = have long spatial correlation distances (many hundreds of km) which = would enable noise reduction by subtraction of digitized signal from a = distant receiver (much farther from the transmitter), from the digitized = signal of the local receiver. I don’t know if the spatial = correlation lengths are anywhere near as long at 23 Hz as at 1 Hz (23 Hz = has a greater ratio of sferic noise to magnetotelluric noise), but still = wonder if you could subtract raw data from another receiver perhaps 170 = - 230 km away to cancel 23 Hz noise captured by your local receiver? =     

 

73,

Jim AA5BW    

 

 

 

From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of = DK7FC
Sent: Thursday, December 20, 2018 1:09 = PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: = SLF: EbNaut @ 80 Hz

 

SLF, =

For the completion of this thread, here is the reprocessed = spectrogram of a DFCW-5400 message at 80 Hz (attachment).
It is just = a small distance but anyway challenging, on the TX side as well as on = the RX side.
Usually i want to detect a carrier, then an EbNaut = message and finally a DFCW message when visiting one of these really low = bands.

Next step is ELF at 23 Hz but this is even more = challenging. Thus there is some delay...

73, Stefan


Am = 27.11.2018 09:25, schrieb DK7FC:

Hi = SLF,

Yesterday, a 45 character EbNaut was transmitted at 80.005 = Hz. It was received on my tree in 3.5 km distance. After the improvement = of the RX antenna it looks like i gained about 2.5 dB SNR. It was an = easy decode, the message could have been transmitted 4 times faster. =
Capture attached :-)

73, Stefan

PS: With that SNR, a 5 = character message could be transferred out to 7 km distance in less than = 1 day.



Am 23.11.2018 10:21, schrieb DK7FC: =

Dear SLF friends,

A new step = forward towards DC: Since yesterday 22:30 UTC i'm TXing a carrier at = 80.005 Hz. That's the 3750 km band, where the far field = begins at a distance of 598 km.

The antenna voltage is just 5 kV = and i'm getting 1.2 mA antenna current, giving an ERP of  20 = fW (2E-14 W).

The voltage is even higher than in my recent = experiment on 270 Hz, anyway the S/N is lower, indicating that my RX = lacks of sensitivity. Indeed this experiment helps to estimate the lack = of sensitivity. Looks like i'm missing about 10 dB on that frequency. = Anyway the signal is making the path of 3.5 km to my tree grabber, as = usual shown at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.ht= ml. Not a big distance but still well beyond most garden = fences!
The signal leaves a barely visible trace in the ZEVS window = which is running at 3.8 mHz FFT bin witdh. Unfortunately ZEVS is off the = air since a week or so. actually i wanted to transmit side by side with = ZEVS, of course a bit deeper even.

From a quiet period at night, = i calculated the SNR of a 1 hour carrier period using vlfrx-tools: = carrier S/N: 16.83 dB in 277.8 uHz, -18.73 dB in 1Hz

For = the crazy homebrewers i'd like to share that website where i ordered the = HV-transformer, http://www.h= osin.de/Specials/HV-Trafo/hv-trafo.html A nightmare for all = safety-fetishists! For the completeness it must be mentioned together = with that page: http://kurts-werkstatt.de= /hv-trafo.htm

73, Stefan

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