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[195.171.43.25]) by mx.google.com with ESMTP id pv1si4418472wjc.65.2014.03.06.03.51.50 for ; Thu, 06 Mar 2014 03:51:51 -0800 (PST) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1WLW1f-00073Q-Ux for rs_out_1@blacksheep.org; Thu, 06 Mar 2014 10:59:43 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WLW1f-00073H-CT for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2014 10:59:43 +0000 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82) (envelope-from ) id 1WLW1d-0002ef-5h for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2014 10:59:42 +0000 Received: from crusoe.iup.uni-heidelberg.de (crusoe.iup.uni-heidelberg.de [129.206.22.248]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id s26Axdbm030163 for ; Thu, 6 Mar 2014 11:59:39 +0100 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by crusoe.iup.uni-heidelberg.de (Postfix) with ESMTP id 5575AE0DBF for ; Thu, 6 Mar 2014 11:59:39 +0100 (CET) Message-ID: <5318551B.4080605@iup.uni-heidelberg.de> Date: Thu, 06 Mar 2014 11:59:39 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= 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: <5316EA0B.4020001@abelian.org> <004001cf3870$27cb9620$6401a8c0@JAYDELL> <53173FCD.9010808@abelian.org> <5317A9C5.2050303@tele2.se>, In-Reply-To: X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi Bob, Markus, Another thing is the coil losses. You will need about 10x more L to resonate the antenna when going down from 29.5 kHz to 8.27 kHz. Oh, that would be 300 kV if Bob wants to run the same antenna current :-) So he has to reduce the power by 20 dB, if the overall losses would be the same! Even with that 300kV, the ERP would be 10 dB lower and the background noise on 8.27 is much higher! This will become a gigantic coil if you want to use the same wire diameter. And if you will reduce it, the coil losses will rise even more, not only due to the higher length of the wire. The coil will be extremely big anyway :-) Hmm, fascinating... [...] 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 [129.206.100.212 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: cbf9d9751ac5f32708197d03fa6d8d74 Subject: Re: LF: Re: VLF 29501, signal? Content-Type: multipart/alternative; boundary="------------010804040408060105050505" 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. --------------010804040408060105050505 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Bob, Markus, Another thing is the coil losses. You will need about 10x more L to resonate the antenna when going down from 29.5 kHz to 8.27 kHz. Oh, that would be 300 kV if Bob wants to run the same antenna current :-) So he has to reduce the power by 20 dB, if the overall losses would be the same! Even with that 300kV, the ERP would be 10 dB lower and the background noise on 8.27 is much higher! This will become a gigantic coil if you want to use the same wire diameter. And if you will reduce it, the coil losses will rise even more, not only due to the higher length of the wire. The coil will be extremely big anyway :-) Hmm, fascinating... 73, Stefan/DK7FC Am 06.03.2014 04:47, schrieb Bob Raide: > Markus; > It is even worse using the same short ant, say that I am using on 29 > at 800 w. I would say a power reduction of several db would be > required and added to your calculated signal reduction when going from > 29 to 9 kHz-Bob > > ------------------------------------------------------------------------ > From: markusvester@aol.com > To: rsgb_lf_group@blacksheep.org > Date: Thu, 6 Mar 2014 00:08:04 +0100 > Subject: Re: LF: Re: VLF 29501, signal? > > Johan, > unfortunately the difference between "upper and lower" VLF will be > much larger than that. Operating a small electric antenna at the same > voltage limit, radiated power scales with the fourth power of > frequency. A current limited TX loop would scale the same way. Thus > going from 29.5 to 8.27 kHz will reduce the fieldstrength by 22 dB. In > addition, background noise from distant static tends to peak around 9 > kHz, which may easily make another 10 dB SNR deterioration. > But well, challenges are there for us to meet them ;-) > Best 73, > Markus > > *From:* Johan Bodin > *Sent:* Wednesday, March 05, 2014 11:48 PM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* Re: LF: Re: VLF 29501, signal? > > Yes, an impressive achievement indeed, congratulations to all involved! > > Wow is the word! The 24dB S/N ratio on Dex' signal exceeded all my > expectations! 24 dB S/N is "armchair copy". It would be interesting to > actually listen to a spectrally shifted and time compressed version of > the signal. Can you do that on your Linux box Paul? Not for scientific > purposes but for pure sheer joy :-) > > Given 24dB S/N headroom at 29.5kHz, sub 9 kHz TA is probably not too far > away! The TX antenna would be no more than ~10dB down compared to 30k. > > 73 > Johan SM6LKM > > ... --------------010804040408060105050505 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Bob, Markus,

Another thing is the coil losses. You will need about 10x more L to resonate the antenna when going down from 29.5 kHz to 8.27 kHz. Oh, that would be 300 kV if Bob wants to run the same antenna current :-) So he has to reduce the power by 20 dB, if the overall losses would be the same! Even with that 300kV, the ERP would be 10 dB lower and the background noise on 8.27 is much higher!
This will become a gigantic coil if you want to use the same wire diameter. And if you will reduce it, the coil losses will rise even more, not only due to the higher length of the wire. The coil will be extremely big anyway :-)
Hmm, fascinating...

73, Stefan/DK7FC

Am 06.03.2014 04:47, schrieb Bob Raide:
Markus;
It is even worse using the same short ant, say that I am using on 29 at 800 w.  I would say a power reduction of several db would be required and added to your calculated signal reduction when going from 29 to 9 kHz-Bob
 
From: markusvester@aol.com
To: rsgb_lf_group@blacksheep.org
Date: Thu, 6 Mar 2014 00:08:04 +0100
Subject: Re: LF: Re: VLF 29501, signal?

Johan,
 
unfortunately the difference between "upper and lower" VLF will be much larger than that. Operating a small electric antenna at the same voltage limit, radiated power scales with the fourth power of frequency. A current limited TX loop would scale the same way. Thus going from 29.5 to 8.27 kHz will reduce the fieldstrength by 22 dB. In addition, background noise from distant static tends to peak around 9 kHz, which may easily make another 10 dB SNR deterioration.
 
But well, challenges are there for us to meet them ;-)
 
Best 73,
Markus

Sent: Wednesday, March 05, 2014 11:48 PM
Subject: Re: LF: Re: VLF 29501, signal?

Yes, an impressive achievement indeed, congratulations to all involved!

Wow is the word! The 24dB S/N ratio on Dex' signal exceeded all my
expectations! 24 dB S/N is "armchair copy". It would be interesting to
actually listen to a spectrally shifted and time compressed version of
the signal. Can you do that on your Linux box Paul? Not for scientific
purposes but for pure sheer joy :-)

Given 24dB S/N headroom at 29.5kHz, sub 9 kHz TA is probably not too far
away! The TX antenna would be no more than ~10dB down compared to 30k.

73
Johan SM6LKM

...
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