Date: Sun, 07 Dec 2014 16:53:58 +0100
From: uwe-jannsen@kabelmail.de
To: rsgb_lf_group@blacksheep.org
Message-ID: <9de867bc104047eb8c50ff961a0514ef@kabelmail.de>
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Subject: Re: Re: VLF: 8270 Hz
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Markus, Paul=20

sri, no transmission today because of rain=2E=20

the last =A0days transmission was not so good conc the phase stability=2E=
=20

during transmission I made some experiments in graphic and observed the=
 phase was jumping from zero to almost 180dgr when moving pics on the s=
creen from one side to the other=2E Working cond: old PC with windoof X=
P prof=2E=20

Until later when the sky is blue agn=2E =20

Uwe/dj8wx =20

Von: rsgb_lf_group@blacksheep=2Eorg
 Gesendet: 06=2E12=2E2014 19:40
 An: rsgb_lf_group@blacksheep=2Eorg
 Betreff: Re: VLF: 8270 Hz

 > Uwe, back again this afternoon?

 Some signals on the band would be handy=2E

 Trying to test new E-field rx against old with the two
 planted side by side on a bleak moorland hillside=2E

 Needed some weak signal so made up a little near field tx
 starting with 280V to a 'long' wire, 3m long 1m high=2E

 150m away from the rx with a small plantation of trees in
 between but the signal was way too strong=2E Ended up with
 a few volts from a sound card onto the wire=2E

 New rx design models well and it tests pretty good on the
 bench, but when deployed performs poorly=2E Noise floor is
 consistently 1=2E4dB higher on the new rx than the old, and
 the old one is quite noisy anyway=2E I've no idea where the
 noise is coming from=2E Thermal noise of ground resistance?
 No, the new rx has a better ground=2E

 It's a black art, this stuff=2E A VLF rx is just an audio
 amplifier, how hard can that be?

 The antenna too is fighting back=2E Despite sealing with
 O-rings, flexible sealant, and layers of self amalgamating
 tape, it still manages to fill with water after a few
 days of rain=2E

 When I eventually get this thing running and calibrated,
 the spectrogram at

 http://abelian=2Eorg/vlf/fbins=2Eshtml

 will gain a dB or two sensitivity and be steerable
 modulo 360 degrees instead of 180=2E
 --
 Paul Nicholson
 --
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<div style=3D"margin: 5px;padding:0;font-family: Arial; font-size: 13px=
;"><p><span>Markus, Paul</span></p>
<p><span>sri, no transmission today because of rain=2E</span></p>
<p><span>the last &nbsp;days transmission was not so good conc the phas=
e stability=2E</span></p>
<p><span>during transmission I made some experiments in graphic and obs=
erved the phase was jumping from zero to almost 180dgr when moving pics=
 on the screen from one side to the other=2E Working cond: old PC with =
windoof XP prof=2E</span></p>
<p><span></span><span>Until later when the sky is blue agn=2E</span> </=
p>
<p><span></span><span>Uwe/dj8wx </span></p>
<div style=3D"background-color: #f9f9f9; line-height: 20px; padding: 5p=
x; border-top: 1px solid #dfdfdf;" class=3D"replyHeader"><strong style=3D=
"width: 80px; display: inline-block; font-size: 95%;">Von:</strong> rsg=
b_lf_group@blacksheep=2Eorg<br />
<strong style=3D"width: 80px; display: inline-block; font-size: 95%;">G=
esendet:</strong> 06=2E12=2E2014 19:40<br />
<strong style=3D"width: 80px; display: inline-block; font-size: 95%;">A=
n:</strong> rsgb_lf_group@blacksheep=2Eorg<br />
<strong style=3D"width: 80px; display: inline-block; font-size: 95%;">B=
etreff:</strong> Re: VLF: 8270 Hz<br />
</div>
<br />
&gt; Uwe, back again this afternoon?<br />
<br />
Some signals on the band would be handy=2E<br />
<br />
Trying to test new E-field rx against old with the two<br />
planted side by side on a bleak moorland hillside=2E<br />
<br />
Needed some weak signal so made up a little near field tx<br />
starting with 280V to a 'long' wire, 3m long 1m high=2E<br />
<br />
150m away from the rx with a small plantation of trees in<br />
between but the signal was way too strong=2E  Ended up with<br />
a few volts from a sound card onto the wire=2E<br />
<br />
New rx design models well and it tests pretty good on the<br />
bench, but when deployed performs poorly=2E  Noise floor is<br />
consistently 1=2E4dB higher on the new rx than the old, and<br />
the old one is quite noisy anyway=2E  I've no idea where the<br />
noise is coming from=2E  Thermal noise of ground resistance?<br />
No, the new rx has a better ground=2E<br />
<br />
It's a black art, this stuff=2E  A VLF rx is just an audio<br />
amplifier, how hard can that be?<br />
<br />
The antenna too is fighting back=2E  Despite sealing with<br />
O-rings, flexible sealant, and layers of self amalgamating<br />
tape, it still manages to fill with water after a few<br />
days of rain=2E<br />
<br />
When I eventually get this thing running and calibrated,<br />
the spectrogram at<br />
<br />
http://abelian=2Eorg/vlf/fbins=2Eshtml<br />
<br />
will gain a dB or two sensitivity and be steerable<br />
modulo 360 degrees instead of 180=2E<br />
--<br />
Paul Nicholson<br />
--<br /></div>
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