Return-Path: X-Spam-DCC: paranoid 1170; Body=3 Fuz1=3 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,HTML_40_50, HTML_MESSAGE autolearn=unavailable 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 s83Jjtj8000385 for ; Wed, 3 Sep 2014 21:45:55 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1XPGPR-0007jA-Ex for rs_out_1@blacksheep.org; Wed, 03 Sep 2014 20:40:01 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1XPGPQ-0007iw-RC for rsgb_lf_group@blacksheep.org; Wed, 03 Sep 2014 20:40:00 +0100 Received: from omr-d01.mx.aol.com ([205.188.252.208]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82) (envelope-from ) id 1XPGPN-0006cd-2N for rsgb_lf_group@blacksheep.org; Wed, 03 Sep 2014 20:39:59 +0100 Received: from mtaout-mca02.mx.aol.com (mtaout-mca02.mx.aol.com [172.26.221.78]) by omr-d01.mx.aol.com (Outbound Mail Relay) with ESMTP id 49F177000009F for ; Wed, 3 Sep 2014 15:39:53 -0400 (EDT) Received: from White (unknown [95.90.198.27]) by mtaout-mca02.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 6530C38000087 for ; Wed, 3 Sep 2014 15:39:50 -0400 (EDT) Message-ID: <4D3C4BE10E3F4156B47D17308D1C7F68@White> From: "Markus Vester" To: References: <54070CEC.2060303@psk31.plus.com> <8D1959D37CE4709-218C-BF72@webmail-va036.sysops.aol.com> Date: Wed, 3 Sep 2014 21:32:21 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20140625; t=1409773193; bh=c6lnHq4KghprgccAxikyE8+OX7MliPMpRk1NIbRGyQE=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=GtbfIuSGEbvl9vUR49jC/2yOxmE/6HY7+WNKb0JdSIwFV4AtfAPOKbCR1cbKMlEMY uhsALo93WDsJI8AAMiWv1AjBbqzhzGfWql+E9aquHw64A1+b9k0dAuFNWzmsnZErjY XmsmoH8rmSb70UiPpnk3tByPZthRxZroNALZOUco= x-aol-sid: 3039ac1add4e54076e867d05 X-AOL-IP: 95.90.198.27 X-Scan-Signature: ce481d129b1a7277ee248e941d6e5100 Subject: Re: LF: RE: ZEVS question Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01CFC7BE.8B6CA2E0" 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 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 390 Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0006_01CFC7BE.8B6CA2E0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable ... been scratching my head about that 10 dB deficit. Errors in the = scope measurement, or in the effective height estimate? There are = uncertainties but it seems hard to explain a factor of three. Or has = ZEVS gone to power save mode? I now suspect there may be a more fundamental reason behind the = discrepancy. When converting from magnetic to electric field, I had = simply assumed that their ratio is the free space wave impedance Z0, ie. = E / H =3D 377 ohms, or equivalently E / B =3D c. However in a waveguide = whose height (60 km) is smaller than the wavelength (3600 km), this may = no longer be the case, but the wave impedance could be less. Then on a = relative scale, magnetic antennas would be more effective than electric = antennas (even though in practice it still seems much easier to receive = the Schumann's on a whip than a loop). This could also explain why the = formula for radiated power on http://en.wikipedia.org/wiki/Ground_dipole = predicts an order of magnitude more radiation than my simple = loop-in-free-space approach. 73, Markus PS. Most likely I'm stumbling upon things which have been known for = decades. For me, it's new and fascinating anyhow.... From: Markus Vester=20 Sent: Wednesday, September 03, 2014 4:48 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: RE: ZEVS question Eddie, Stefan, yes I was surprised and exhilarated to find the Schumann humps along = with the 82 Hz signal. The quest to see those always seemed like some = kind of holy grail regarding low frequency work ;-) Actually I had tried to see ZEVS a couple of times in the past without = success. But that was without any preamplification, suffering from = severe mismatch loss between the small antenna capacitance and the 1 = kohm soundcard input. Another attempt using the 6 squaremeter magnetic = loops in the garden also failed due to low induction voltage and = coupling to underground cables. The source follower has only a couple of resistors at the gate, 2.5 Mohm = in series and 10 Mohm shunt. Together with the capacitances of antenna = (270 pF) and a piece of coax (200 pF), the shunt makes a cutoff at 27 = Hz. There is a 10 uF coupling capacitor to the soundcard which inserts = another pole at 10 Hz, and in addition the soundcard internally fades = out below about 7 Hz. Connecting a scope to the source, I am seeing monster signals from the = grids, about 1.2 V pp on 16.7 Hz (railway at 400m) plus 0.3 Vpp on 50 Hz = (relatively weak due to underground supply lines). The recording gain = slider is set low such that the ADC input range is about 2 Vpp. With 75% = of clipping levels, the little SpecLab input scope just occasionally = becomes red. Note that all software postprocessing (like noiseblanking = or notch filtering) is disabled. Working back through mismatch, frequency response, and antenna height, = the interfering fieldstrength at this location is around 1.2 V/m at 16 = Hz and 0.15 V/m at 50 Hz. The railway also has a strong fifth harmonic = around 83.3 Hz, which is about half a Hz wide but fortunately doesn't = seem to leak much into the ZEVS band.=20 The ZEVS carrier itself reaches -91 dB fullscale, translating to about = 30 uV/m or 0.1 picoTesla. From Fig.2 in = http://www-ee.stanford.edu/~acfs/82Hz.pdf, the fieldstrength at 2.5 Mm = should be -130 dBA/m or 0.4 picotesla in the main lobes (77 and 257 = degrees azimuth). At 220=C2=B0 from Murmansk, one would expect a = reduction by cos(37=C2=B0), giving 0.32 pT. Thus my observation is still = about 10 dB short of expectation. There also seems to be a bit of = diurnal variation both in Schumann and ZEVS levels, exhibiting a shallow = minimum at sunrise. Best 73, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: g3zjo An: rsgb_lf_group Verschickt: Mi, 3 Sept 2014 2:44 pm Betreff: Re: LF: RE: ZEVS question Hi Makus, Stefan, All Very jealous here of Markus' Schumann resonances, the response of my = E-Probe filter necessarily cuts off at that end. I did try different responses a while ago and if I let much 50Hz in it = overwhelms everything at this location. It is nice to be able to see the 16.7Hz and harmonic which is sort of DX = here. 73 Eddie G3ZJO On 02/09/2014 23:45, Markus Vester wrote:=20 Hi Eddie, LF group, it looks like despite very strong 50 Hz and 16.7 Hz harmonics, I can = still receive useful ELF signals from my Marconi (currently only 3 m = above the roof) with a simple BF245 source follower. The top panel of my = VLF grabber http://www.df6nm.de/vlf/vlfgrabber.htm currently shows the = ZEVS carrier, as well as several Schumann resonances. Best 73, Markus (DF6NM) From: g3zjo=20 Sent: Tuesday, September 02, 2014 11:14 AM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: RE: ZEVS question As part of my checking that everything is OK and ready for the next=20 tests on ELF/ULF/SLF ? I have my Grabber http://www.g3zjo.talktalk.net/vlfgrabber.htm Live on Wide and ZEVS. ZEVS is showing a good carrier at this time in = my=20 urban environment. 73 Eddie G3ZJO ... ------=_NextPart_000_0006_01CFC7BE.8B6CA2E0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
... been scratching my head about that = 10 dB=20 deficit. Errors in the scope measurement, or in the effective height = estimate?=20 There are uncertainties but it seems hard to explain a factor of = three. Or=20 has ZEVS gone to power save mode?
 
I now suspect there may be a more = fundamental=20 reason behind the discrepancy. When converting from magnetic to = electric=20 field, I had simply assumed that their ratio is the free space wave = impedance Z0, ie. E / H =3D 377 ohms, = or equivalently=20 E / B =3D c. However in a = waveguide whose=20 height (60 km) is smaller than the wavelength (3600 km), this may = no longer=20 be the case, but the wave impedance could be less. Then = on a=20 relative scale, magnetic antennas would be more effective than = electric antennas (even though in practice it still=20 seems much easier to receive the Schumann's on a whip than a = loop).=20 This could also explain why the formula for radiated power on = http://en.wikipedia.o= rg/wiki/Ground_dipole predicts an order of magnitude more radiation = than my=20 simple loop-in-free-space approach.
 
73, Markus
 
PS. Most likely I'm stumbling = upon things=20 which have been known for decades. For me, it's new and fascinating=20 anyhow....
 

Sent: Wednesday, September 03, 2014 4:48 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: Re: LF: RE: ZEVS question

Eddie, Stefan,
 
yes I = was=20 surprised and exhilarated to find the Schumann humps along with the 82 = Hz=20 signal. The quest to see those always seemed like some kind of holy = grail=20 regarding low frequency work ;-)
 
Actually I had=20 tried to see ZEVS a couple of times in the past without success. But = that was=20 without any preamplification, suffering from severe mismatch loss = between the=20 small antenna capacitance and the 1 kohm soundcard input. Another = attempt using=20 the 6 squaremeter magnetic loops in the garden also failed due to low = induction=20 voltage and coupling to underground cables.
 
The = source=20 follower has only a couple of resistors at the gate, 2.5 Mohm in series = and 10=20 Mohm shunt. Together with the capacitances of antenna (270 pF) and a = piece of=20 coax (200 pF), the shunt makes a cutoff at 27 Hz. There is a 10 uF = coupling=20 capacitor to the soundcard which inserts another pole at 10 Hz, and in = addition=20 the soundcard internally fades out below about 7 Hz.
 
Connecting a=20 scope to the source, I am seeing monster signals from the grids, about = 1.2 V pp=20 on 16.7 Hz (railway at 400m) plus 0.3 Vpp on 50 Hz (relatively weak due = to=20 underground supply lines). The recording gain slider is set low such = that the=20 ADC input range is about 2 Vpp. With 75% of clipping levels, the little = SpecLab=20 input scope just occasionally becomes red. Note that all software = postprocessing=20 (like noiseblanking or notch filtering) is disabled.
 
Working = back=20 through mismatch, frequency response, and antenna height, the = interfering=20 fieldstrength at this location is around 1.2 V/m at 16 Hz and 0.15 V/m = at 50 Hz.=20 The railway also has a strong fifth harmonic around 83.3 Hz, which is = about half=20 a Hz wide but fortunately doesn't seem to leak much into the ZEVS band. =
 
The = ZEVS carrier=20 itself reaches -91 dB fullscale, translating to about 30 uV/m or 0.1 = picoTesla.=20 >From Fig.2 in http://www-ee.stanford= .edu/~acfs/82Hz.pdf,=20 the fieldstrength at 2.5 Mm should be -130 dBA/m or 0.4  picotesla = in the=20 main lobes (77 and 257 degrees azimuth). At 220=C2=B0 from Murmansk, one = would expect=20 a reduction by cos(37=C2=B0), giving 0.32 pT. Thus my observation is = still about 10=20 dB short of expectation. There also  seems to be a bit of diurnal = variation=20 both in Schumann and ZEVS levels, exhibiting a shallow minimum at = sunrise.
 
Best=20 73,
Markus (DF6NM)


-----Urspr=C3=BCngliche Mitteilung-----
Von: g3zjo=20 <g3zjo@psk31.plus.com>
An: rsgb_lf_group=20 <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 3 Sept 2014 2:44 = pm
Betreff: Re: LF: RE: ZEVS question

Hi = Makus, Stefan,=20 All

Very jealous here of Markus' Schumann resonances, the = response of my=20 E-Probe filter necessarily cuts off at that end.
I did try different=20 responses a while ago and if I let much 50Hz in it overwhelms everything = at this=20 location.
It is nice to be able to see the 16.7Hz and harmonic which = is sort=20 of DX here.

73 Eddie G3ZJO

On 02/09/2014 23:45, Markus = Vester=20 wrote:=20
Hi Eddie, LF group,
 
it looks like despite very = strong 50 Hz=20 and 16.7 Hz harmonics, I can still receive useful ELF = signals from my=20 Marconi (currently only 3 m above the roof) with a simple = BF245=20 source follower. The top panel of my VLF = grabber http://www.df6nm.de/vlf/vlfgrabber.htm currently= =20 shows the ZEVS carrier, as well as several Schumann=20 resonances.
 
Best 73,
Markus (DF6NM)
 

From: g3zjo
Sent: Tuesday, September 02, 2014 11:14 AM
To: rsgb_lf_group@blacksheep.org= =20
Subject: Re: LF: RE: ZEVS question

As part of my checking that everything is OK and ready = for the=20 next
tests on ELF/ULF/SLF ? I have my Grabber
  http://www.g3zjo.talktalk.net/vlfgrabber.htm
Live = on Wide=20 and ZEVS. ZEVS is showing a good carrier at this time in my
urban=20 environment.

73 Eddie=20 G3ZJO

...

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