Return-Path: X-Spam-DCC: paranoid 1170; Body=3 Fuz1=2 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE,NO_REAL_NAME,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u3JLPphl007108 for ; Tue, 19 Apr 2016 23:25:52 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1asd4i-0006E9-PL for rs_out_1@blacksheep.org; Tue, 19 Apr 2016 22:20:48 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1asd4i-0006E0-D5 for rsgb_lf_group@blacksheep.org; Tue, 19 Apr 2016 22:20:48 +0100 Received: from resqmta-ch2-12v.sys.comcast.net ([2001:558:fe21:29:69:252:207:44]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1asd4f-0006AA-Cc for rsgb_lf_group@blacksheep.org; Tue, 19 Apr 2016 22:20:47 +0100 Received: from resomta-ch2-16v.sys.comcast.net ([69.252.207.112]) by comcast with SMTP id sd2SaIphCgEHvsd4cahvbM; Tue, 19 Apr 2016 21:20:42 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1461100842; bh=CZm6EHr913R5u6MTVe1b6bsnHgZ3d5iGhAa6sQAMO0w=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=aDJjB/4zZN6dAtLT+bhXwCRk0FsmLXWC+QtitlMOXRkc+y1RA3sD+9Pzs9EfRbxmJ pzx0bOmlsJfLgVqoVzWNYxGASb8aDVB4mBPHowTGGQ8hST/R2IS/KMT6H+zy4adEkj z6HorTEtXaYZ6wLEGn7GGO82cQN2uqbSS/252XmFFI3XZ8fD5/qPs7a+IToil4drO9 89qZUs7L7RGXvf+cHg9mb8lr7q7kdExZ5WSbgX6Sj696GKH9L3qHKU6ZNoxP46Tx3a 9avkzI5+bclHoIFOKVgBtHKEvbzr5vMze6D4mgZQf+ddzMwYVrf3VDEBI5Vo5h9/U7 66UlgaHZ/v/iQ== Received: from Owner ([IPv6:2601:141:0:bec5:ed09:d56e:2d7d:e449]) by resomta-ch2-16v.sys.comcast.net with comcast id kMLg1s00e4R9ofC01MLhQC; Tue, 19 Apr 2016 21:20:41 +0000 From: To: References: <8D3687799046F9F-15C4-93AEC4@webmail-vm170.sysops.aol.com> In-Reply-To: <8D3687799046F9F-15C4-93AEC4@webmail-vm170.sysops.aol.com> Date: Tue, 19 Apr 2016 16:55:08 -0400 Message-ID: <04cf01d19a81$4f3950b0$edabf210$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQHU1Qy9XGDXXr3Ogs0fPwyDcjiacp+LPBAg Content-Language: en-us X-Scan-Signature: f6bad70c4aa77b0bf5528aff34072d8d Subject: LF: RE: 8270.0025 Tuesday Apr 19 Content-Type: multipart/alternative; boundary="----=_NextPart_000_04D0_01D19A5F.C828E930" 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 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7790 This is a multipart message in MIME format. ------=_NextPart_000_04D0_01D19A5F.C828E930 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Markus, Nice signal! A question perhaps for Paul or yourself follows: At ~0.22 fT (estimated from Paul's spectrogram) I expected to see >> 10dB SNR in 278uHz. 10dB SNR is off scale so I looked at the on/off tails and noise, and I still seemed to be off by a substantial amount in the relationship of flux density and SNR in Paul's spectrogram, but I had not factored in sferic noise and cancellation. If I assume 30fT/rt-Hz for sferics, and 20dB sferic noise cancellation in a clipper, then a 0.22fT signal (with 3.0 fT/rt-Hz sferic noise after clipping) would yield roughly 13dB SNR in 278uHz, which seems consistent with Paul's spectrogram. My question is: Is 20dB noise reduction a reasonable estimate for the sferic clipper/blanker? I think that I had become accustomed over the winter to seeing near-preamp-noise-limited SNR on a number of VLF receivers, notwithstanding sub-fT/rt-Hz preamp noise levels, and that may explain why I was expecting >>10dB SNR for ~0.22fT and noise in 278 uHz. If Paul considers the sferic clipper/blanker noise reduction to be roughly 20dB that would explain my overestimate. Nice signal from your (9m?) antenna! 73, Jim AA5BW From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus Vester Sent: Tuesday, April 19, 2016 1:25 PM To: rsgb_lf_group@blacksheep.org Subject: VLF: 8270.0025 Tuesday Apr 19 After a couple of minor modifications (different soundcard, thicker piece of wire from the top of the loading coil), I ran a test carrier from 13:15 to 15:15 UT. I briefly ventured pushing the drive up to 0.42 A (= 30.0 kV rms) with no adverse effects, but then settled to 0.35 A to have a bit of margin for the long transmission. Unfortunately not much appeared in Heidelberg and Breclav in the upcoming afternoon QRN. But then, looking at Paul's spectrogram saved my day: http://abelian.org/vlf/fbins.shtml#p=1461078000 &b=110&s=sp All the best, Markus (DF6NM) ------=_NextPart_000_04D0_01D19A5F.C828E930 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Markus,

 

Nice signal!

 

A question perhaps for Paul or yourself = follows:

 

At ~0.22 fT (estimated from Paul’s spectrogram) I expected to = see >> 10dB SNR in 278uHz.  10dB SNR is off scale so I looked = at the on/off tails and noise, and I still seemed to be off by a = substantial amount in the relationship of flux density and SNR in = Paul’s spectrogram, but I had not factored in sferic noise and = cancellation.

If I assume 30fT/rt-Hz for sferics, and 20dB sferic noise = cancellation in a clipper, then a 0.22fT signal (with 3.0 fT/rt-Hz = sferic noise after clipping) would yield roughly 13dB SNR in 278uHz, = which seems consistent with Paul’s = spectrogram.

 

My question is:

Is 20dB noise reduction a reasonable estimate for the sferic = clipper/blanker?

 

I think that I had become accustomed over the winter to seeing = near-preamp-noise-limited SNR on a number of VLF receivers, = notwithstanding sub-fT/rt-Hz preamp noise levels, and that may explain = why I was expecting >>10dB SNR for ~0.22fT and noise in 278 = uHz.  If Paul considers the sferic clipper/blanker noise reduction = to be roughly 20dB that would explain my overestimate. =

 

Nice signal from your (9m?) antenna!

 

73,

Jim AA5BW

 

 

From:= = owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus = Vester
Sent: Tuesday, April 19, 2016 1:25 PM
To: = rsgb_lf_group@blacksheep.org
Subject: VLF: 8270.0025 Tuesday = Apr 19

 

After a couple of minor modifications (different = soundcard, thicker piece of wire from the top of the loading = coil), I ran a test carrier from 13:15 to 15:15 UT. I = briefly ventured pushing the drive up to 0.42 A (=3D 30.0 kV = rms) with no adverse effects, but then settled to 0.35 A to have a = bit of margin for the long transmission. Unfortunately not much appeared = in Heidelberg and Breclav in the upcoming afternoon QRN. = But then, looking at Paul's spectrogram saved my day: =

 

All the best,

Markus (DF6NM)


 

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