Date: Wed, 9 Aug 2017 13:00:29 -0400
From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: VLF: Carrier on 3675.005 Hz
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Hi Paul,

> Not much use continuing with carrier when I only have half a receiver

> but the system noise is still consistently 0.1 dB worse than the existing=
 rx

Hmm, loosing 3 dB or more while attempting to gain the last 0.1 dB - someti=
mes being perfectionist can be a curse ;-)

All the best,
Markus


-----Urspr=C3=BCngliche Mitteilung-----=20
Von: Paul Nicholson <vlf0403@abelian.org>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 9. Aug 2017 15:43
Betreff: Re: VLF: Carrier on 3675.005 Hz


I'm measuring about 0.016 fT daytime, 0.045 fT nighttime.

Daytime signal phase leads the night phase by about 67 degrees.

Combining and normalising day/night signals and excluding
the terminator periods gives

http://abelian.org/vlf/tmp/170809a.gif

Still not significant, only about 3.5 sigma, 10.9 dB S/N
in 1.13 uHz.

 > Seems the result is even poorer than on 2.97 kHz?

Probably just because I'm not using the E-field.

 > i would try some first EbNaut on that 82 km band over
> to DL0AO in 226 km.

Yes, if the S/N is good enough at DL0A0. Not much use continuing
with carrier when I only have half a receiver.

This afternoon I'll do some more work on the new E-field rx.
Running side-by-side comparison with the old rx.

I've been working on the new rx for over 2 years but the system
noise is still consistently 0.1 dB worse than the existing rx.
The front-end noise of the new rx is lower but the bandwidth is
wider. The extra signal is raising the noise floor slightly
due to a tiny amount of distortion in the line driver and
isolating transformers. On the test bench the new rx does very
well: very low noise and low distortion. But with the full
signal from the antenna there is enough mixing to slightly raise
the noise floor. I just need that 0.1 dB and also to cure some
mechanical noises (microphonics) when the wind blows.

PS, the new rx also also covers 137 kHz!

--
Paul Nicholson
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<div style=3D"font-size:10pt;font-family:arial,helvetica,sans-serif;color:b=
lack;"><div style=3D"color: black; font-family: arial,helvetica,sans-serif;=
 font-size: 10pt;">Hi Paul,<br><br>&gt; Not much use continuing with carrie=
r when I only have half a receiver<br><br>&gt; but the system noise is stil=
l consistently 0.1 dB worse than the existing rx<br><br>Hmm, loosing 3 dB o=
r more while attempting to gain the last 0.1 dB -&nbsp;sometimes being&nbsp=
;perfectionist can be a curse ;-)<br><br>All the best,<br>Markus<br><br><br=
>-----Urspr=C3=BCngliche Mitteilung----- <br>Von: Paul Nicholson &lt;vlf040=
3@abelian.org&gt;<br>An: rsgb_lf_group &lt;rsgb_lf_group@blacksheep.org&gt;=
<br>Verschickt: Mi, 9. Aug 2017 15:43<br>Betreff: Re: VLF: Carrier on 3675.=
005 Hz<br><br></div><br>I'm measuring about 0.016 fT daytime, 0.045 fT nigh=
ttime.<br><br>Daytime signal phase leads the night phase by about 67 degree=
s.<br><br>Combining and normalising day/night signals and excluding<br>the =
terminator periods gives<br><br>  <a href=3D"http://abelian.org/vlf/tmp/170=
809a.gif" target=3D"_blank">http://abelian.org/vlf/tmp/170809a.gif</a><br><=
br>Still not significant, only about 3.5 sigma, 10.9 dB S/N<br>in 1.13 uHz.=
<br><br> &gt; Seems the result is even poorer than on 2.97 kHz?<br><br>Prob=
ably just because I'm not using the E-field.<br><br> &gt; i would try some =
first EbNaut on that 82 km band over<br> &gt; to DL0AO in 226 km.<br><br>Ye=
s, if the S/N is good enough at DL0A0.  Not much use continuing<br>with car=
rier when I only have half a receiver.<br><br>This afternoon I'll do some m=
ore work on the new E-field rx.<br>Running side-by-side comparison with the=
 old rx.<br><br>I've been working on the new rx for over 2 years but the sy=
stem<br>noise is still consistently 0.1 dB worse than the existing rx.<br>T=
he front-end noise of the new rx is lower but the bandwidth is<br>wider.  T=
he extra signal is raising the noise floor slightly<br>due to a tiny amount=
 of distortion in the line driver and<br>isolating transformers.  On the te=
st bench the new rx does very<br>well: very low noise and low distortion.  =
But with the full<br>signal from the antenna there is enough mixing to slig=
htly raise<br>the noise floor.   I just need that 0.1 dB and also to cure s=
ome<br>mechanical noises (microphonics) when the wind blows.<br><br>PS, the=
 new rx also also covers 137 kHz!<br><br>--<br>Paul Nicholson<br>--<br><br>=
</div>
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