Return-Path: X-Spam-DCC: paranoid 1356; Body=2 Fuz1=2 Fuz2=2 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 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 u3U5nbjB006405 for ; Sat, 30 Apr 2016 07:49:37 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1awNhW-0003Fw-9B for rs_out_1@blacksheep.org; Sat, 30 Apr 2016 06:44:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1awNhV-0003Fn-Kz for rsgb_lf_group@blacksheep.org; Sat, 30 Apr 2016 06:44:21 +0100 Received: from resqmta-ch2-11v.sys.comcast.net ([2001:558:fe21:29:69:252:207:43]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1awNhS-0007Yo-JV for rsgb_lf_group@blacksheep.org; Sat, 30 Apr 2016 06:44:20 +0100 Received: from resomta-ch2-20v.sys.comcast.net ([69.252.207.116]) by comcast with SMTP id wNhPaiWKtjuYRwNhPaoBcT; Sat, 30 Apr 2016 05:44:15 +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=1461995055; bh=ECLDLFAXBIXpwCI6X9dleKNsKsDtivsbDHTAsEMelZw=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=FU3aFncF7EEr5ormjzwUVrl+nseJCT2YSMasHYB8hw7wSybFSdEhlvnt1+BeKjtq6 9jSZXRD365elX/xqyQblsieRKmzX98DM7IVJXo3mYntl0KbBCdpDP5nhn7vl4YvtYl bo1QOeOElZ9SzUdR32/QatyAD70sH3OP5m9KAfux/18VqS2uGORj0L/aKsANk9m+VX I4huqFlHcVzs2iTtYHRYcoboDvTKy29snWs/Cl0DCDAxS1CJWQz9NdIRFSWqpP0een zccvHjNC75aWZ0+Eg3OnrZwPGYqp/E6MkvwY/u4qzmuX82EBmfftAqcRtiU7DHFP/V eI9I+B6J/9CVQ== Received: from Owner ([IPv6:2601:141:0:bec5:8dc9:9d20:f03b:e05f]) by resomta-ch2-20v.sys.comcast.net with comcast id oVkE1s0024rWJCU01VkE1g; Sat, 30 Apr 2016 05:44:15 +0000 From: To: Date: Sat, 30 Apr 2016 01:44:11 -0400 Message-ID: <073601d1a2a3$5324e1b0$f96ea510$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AdGioekIjl2p2dbyRuCtO9mprjSlOg== Content-Language: en-us X-Scan-Signature: a832015f9681fcc6d4e2835ba174a7e7 Subject: RE: LF: RE: 8270.0025 Tuesday Apr 19 (belated) Content-Type: multipart/alternative; boundary="----=_NextPart_000_0737_01D1A281.CC14A140" 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: 7937 This is a multipart message in MIME format. ------=_NextPart_000_0737_01D1A281.CC14A140 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hello Markus, =20 Thanks for the information, and sorry for very late reply. =20 Yes, I have definite plans for VLF; have built many good receivers and = good RX antennas; built and carefully tested many bad TX antennas and = good TX antennas; have reliable robust clean 24kW PA (running now, = keeping the room warm); ultra-small dynamic matching unit; have a = Helikite picked out; good RX/TX sites; keep getting sidetracked, in = particular too much time playing with interesting details and improving = components. Trimble Thunderbolt E (E version has good clock stability) = sitting on bench 12 months waiting to be hooked up. Always some reason = to postpone group tests and I don=E2=80=99t even have a cat. =20 =20 73, =20 Jim AA5BW =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus Vester Sent: Wednesday, April 20, 2016 4:07 AM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: RE: 8270.0025 Tuesday Apr 19 =20 Hi Jim, =20 the transmit antenna is physically larger: The apex of the topload is at = 21 m above ground or 12 m above our rooftop. But the wires are sloping = downward at steep angles, and the antenna is partly shielded by = surrounding houses and trees. The effective height was measured as 8.7 = m at 139 kHz by comparison of received open-circuit voltage versus a = small nonresonant loop. I believe that effective height may be about 20% = lower at VLF due to more effective shielding from resistive objects, but = this difference has not been measured so it's just a guess.=20 =20 Thanks Paul for the comparison and valuable details regarding spherics = blanking. =20 Jim, any plans for VLF activities from your end? =20 73, Markus =20 -----Urspr=C3=BCngliche Mitteilung-----=20 Von: hvanesce An: rsgb_lf_group Verschickt: Di, 19 Apr 2016 11:22 pm Betreff: LF: RE: 8270.0025 Tuesday Apr 19 Markus, =20 Nice signal!=20 =20 A question perhaps for Paul or yourself follows: =20 At ~0.22 fT (estimated from Paul=E2=80=99s 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=E2=80=99s = 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=E2=80=99s spectrogram. =20 My question is: Is 20dB noise reduction a reasonable estimate for the sferic = clipper/blanker? =20 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.=20 =20 Nice signal from your (9m?) antenna!=20 =20 73, Jim AA5BW =20 =20 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 =20 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:=20 http://abelian.org/vlf/fbins.shtml#p=3D1461078000 = = &b=3D110&s=3Dsp =20 All the best, Markus (DF6NM) =20 ------=_NextPart_000_0737_01D1A281.CC14A140 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Hello Markus,

 

Thanks for the information, and sorry for very late = reply.

 

Yes, I have definite plans for VLF; have built many good receivers = and good RX antennas; built and carefully tested many bad TX antennas = and good TX antennas; have reliable robust clean 24kW PA (running now, = keeping the room warm); ultra-small dynamic matching unit; have a = Helikite picked out; good RX/TX sites; keep getting sidetracked, in = particular too much time playing with interesting details and improving = components. Trimble Thunderbolt E (E version has good clock stability) = sitting on bench 12 months waiting to be hooked up. Always some reason = to postpone group tests and I don=E2=80=99t even have a cat. = =C2=A0

 

73,

 

Jim AA5BW

 

From:= = owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus = Vester
Sent: Wednesday, April 20, 2016 4:07 AM
To: = rsgb_lf_group@blacksheep.org
Subject: Re: LF: RE: 8270.0025 = Tuesday Apr 19

 

H= i Jim,

&= nbsp;

t= he transmit antenna is physically larger: The apex of the topload is at = 21 m above ground or 12 m above our rooftop. But the wires are = sloping downward at steep angles, and the antenna is partly shielded by = surrounding houses and trees. The effective height was = measured  as 8.7 m at 139 kHz by comparison of received = open-circuit voltage versus a small nonresonant loop. I believe = that effective height may be about 20% lower at VLF due to = more effective shielding from resistive objects, but = this difference has not been measured so it's just a = guess. 

 

Thanks Paul for the comparison and valuable = details regarding spherics blanking.

 
Jim, any plans for VLF activities from = your end?

 

73, Markus


 

-----Urspr=C3=BCngliche Mitteilung-----
Von: = hvanesce <hvanesce@comcast.net>
An: = rsgb_lf_group <rsgb_lf_group@blacksheep.org= >
Verschickt: Di, 19 Apr 2016 11:22 pm
Betreff: LF: RE: = 8270.0025 Tuesday Apr 19

<= p class=3DMsoNormal>Markus,

 

Nice signal! =

 

A question perhaps = for Paul or yourself follows:

 

At ~0.22 fT = (estimated from Paul=E2=80=99s 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=E2=80=99s = 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=E2=80=99s = 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@bl= acksheep.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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