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 wBKMxTvo021084 for ; Thu, 20 Dec 2018 23:59:35 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ga7Ck-0000lz-9I for rs_out_1@blacksheep.org; Thu, 20 Dec 2018 22:54:10 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ga7Bh-0000jT-Hh for rsgb_lf_group@blacksheep.org; Thu, 20 Dec 2018 22:53:05 +0000 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1ga7Bb-00013R-57 for rsgb_lf_group@blacksheep.org; Thu, 20 Dec 2018 22:53:02 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id 8DBD616005F for ; Thu, 20 Dec 2018 23:52:57 +0100 (CET) X-DKIM-Result: Domain=posteo.de Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1545346377; bh=tZnsmN9PfOEsJpZqwHR/h6DKWe8uvnn4UhS2hUp6gGc=; h=Date:From:To:Subject:From; b=WIv/v542ONxfkOxOA+WWnutK1Pb5a9MTe/TSWb4ls6KSb4Vz5+0Cx0dTxa40FpDwm WnFOCmn1L69CwQDPTtUD5dQ3yLDtRuG4LS5LUYLOwmW5e++yowKzDxGJz6GPV047FW sofEwsqWTre8g7cVqI9LHfzzCdUzS0I9juS64mIs5DeUVtZTVDDXV7WMhPI/FocAkR JO6Q8y3bKQ2ge1yqzBbNmb1KG9zFgmGvhaoNM1tfG5rptdxWN/Kc7+iZmHypAfHIAH jl2xax7eLyZtffji96XTKilAEn6yzArzQzMRP3FA/SsQjir9xMO1Zfj8DTx1RIY5Xt /+4Macwt0jWyA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 43LRqX560Cz6tmR for ; Thu, 20 Dec 2018 23:52:56 +0100 (CET) Message-ID: <5C1C1D48.5090807@posteo.de> Date: Thu, 20 Dec 2018 23:52:56 +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: <5BE0C0CE.10008@posteo.de> <5BE19D5E.7000408@posteo.de> <5BF7C6B4.8090104@posteo.de> <5BFCFF7D.8090006@posteo.de> <5C1BDAA0.70409@posteo.de> <008301d498b3$29a600e0$7cf202a0$@comcast.net> In-Reply-To: <008301d498b3$29a600e0$7cf202a0$@comcast.net> X-Spam-Score: -2.3 (--) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. 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Content preview: Hi Jim, Am 20.12.2018 23:26, schrieb hvanesce@comcast.net: > > 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 > [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [185.67.36.65 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 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: 4bc17085406dca8cb02959d4b62a7d31 Subject: Re: SLF: EbNaut @ 80 Hz Content-Type: multipart/alternative; boundary="------------090600020809070509020307" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE 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 multi-part message in MIME format. --------------090600020809070509020307 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Jim, Am 20.12.2018 23:26, schrieb hvanesce@comcast.net: > > 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)? > Yes you do. But the noisy periods were not from QRN but from wind! At least, when i listen to the stream it sounds like wind which is causing E field noise. There must have been some charge somewhere, maybe charged small rain drops. The antenna is grounded by a 100 MOhm resistor. > Is 5400 is equal to or similar to the number of seconds of integration? > There is a feedback loop of the soundcard output to the soundcard input which is there to correct eventual phase glitches. Thus, SpecLabs digimode terminal can't be used to transmit DFCW. That means, i have to write a command line in the scheduled actions for each start and stop (and QSY) of a dash. 5400 is just the length in seconds of each dash. This is 90 minutes and so it is easy to calculate the start and stop times. > It is exciting to read that you are headed toward 23 Hz. > Oh, just a few minutes ago i managed to produce 4 kV rms at 23 Hz. Not as easy as i expected. > > 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? > This is possible in vlf-rx tools and there is a receiver in that distance but i never used the possibility so far. More soon. 73, Stefan > 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 > --------------090600020809070509020307 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Jim,

Am 20.12.2018 23:26, schrieb hvanesce@comcast.net:

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)?

Yes you do. But the noisy periods were not from QRN but from wind! At least, when i listen to the stream it sounds like wind which is causing E field noise. There must have been some charge somewhere, maybe charged small rain drops. The antenna is grounded by a 100 MOhm resistor.

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

There is a feedback loop of the soundcard output to the soundcard input which is there to correct eventual phase glitches. Thus, SpecLabs digimode terminal can't be used to transmit DFCW. That means, i have to write a command line in the scheduled actions for each start and stop (and QSY) of a dash. 5400 is just the length in seconds of each dash. This is 90 minutes and so it is easy to calculate the start and stop times.

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

Oh, just a few minutes ago i managed to produce 4 kV rms at 23 Hz. Not as easy as i expected.

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?

This is possible in vlf-rx tools and there is a receiver in that distance but i never used the possibility so far.
More soon.

73, Stefan

    

 

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

--------------090600020809070509020307--