Date: Mon, 12 Jun 2017 03:53:41 -0400
From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: ELF: ZEVS phase and frequency accuracy?
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It looks like ZEVS has lost a cycle in about 30 hours, corresponding to abo=
ut - 9uHz offset from 82 Hz (assuming I got the sign right). Thus observing=
 it in a very narrow spectrum might indeed allow to separate the true ZEVS =
signal from local interference. However I do not know how the phase would b=
e affected if FSK messages were sent.

Best 73,
Markus

-----Urspr=C3=BCngliche Mitteilung-----=20
Von: Markus Vester <markusvester@aol.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Sa, 10. Jun 2017 22:26
Betreff: ELF: ZEVS phase and frequency accuracy?


I've been wondering whether the 82 Hz carrier from the ZEVS transmitter is =
accurate and synchroneous to UTC. So I set up a colour spectrogram on the D=
L0AO grabber
 http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_dl0ao_test.htm
(scroll down to near the bottom), which shows the phase with reference to a=
 1pps harmonic on the other channel. The colour sequence is red-yellow-gree=
n-blue for retarding ZEVS phase (unfortunately opposite to the way it's don=
e on LoranView).

During the last six hours, the colour has changed from red to green, indica=
ting a 120=C2=B0 delay. This Looks like the carrier is ~ 20 uHz below 82 Hz=
 (-0.25 ppm, quite a large difference on a relative scale). I am asking mys=
elf how it the transmit frequency is physically being steered, possibly "Al=
exanderson-style" by setting the velocity of a rotating machine? If the fre=
quency offset turns out to be real and stable, it could be a means for DX'e=
rs to differentiate the real ZEVS signal from possible local receiver artif=
acts. I wonder whether anyone else could verify the offset?

On the other hand, I wouldn't yet rule out a diurnal propagation effect, ev=
en though at a distance of less than a wavelength this should not produce s=
uch a large phase change. There could also be local effects on the receive =
site from variable humidity in the vegetation near the E-field probe.=20

So the big question is whether or not the phase trend will continue tonight=
 and tomorrow.

Best 73,
Markus (DF6NM)
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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;">It looks like ZEVS has lost a cycle in about 30 hours, c=
orresponding to about - 9uHz offset from 82 Hz (assuming I got the sign rig=
ht). Thus observing it in a very narrow spectrum might indeed allow to sepa=
rate&nbsp;the true ZEVS signal from local interference. However I do not kn=
ow how the phase would be affected if&nbsp;FSK messages were sent.<br><br>B=
est 73,<br>Markus<br><br>-----Urspr=C3=BCngliche Mitteilung----- <br>Von: M=
arkus Vester &lt;markusvester@aol.com&gt;<br>An: rsgb_lf_group &lt;rsgb_lf_=
group@blacksheep.org&gt;<br>Verschickt: Sa, 10. Jun 2017 22:26<br>Betreff: =
ELF: ZEVS phase and frequency accuracy?<br><br></div>
<div id=3D"AOLMsgPart_2_1999f43e-9ee6-44d1-88bf-78a298807845">
<div class=3D"aolReplacedBody"><div style=3D"color: black; font-family: ari=
al,helvetica,sans-serif; font-size: 10pt;">I've been wondering whether the =
82 Hz carrier from the ZEVS transmitter is&nbsp;accurate&nbsp;and synchrone=
ous to UTC. So I set up a colour spectrogram&nbsp;on&nbsp;the DL0AO grabber=
<br>&nbsp;<a href=3D"http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_d=
l0ao_test.htm" target=3D"_blank">http://df6nm.bplaced.net/dl0ao/VLFgrabber/=
vlfgrabber_dl0ao_test.htm</a><br>(scroll down to near the bottom), which sh=
ows the phase with reference to a 1pps harmonic on&nbsp;the other channel. =
The colour sequence is red-yellow-green-blue for retarding ZEVS phase (unfo=
rtunately opposite to&nbsp;the way it's done on LoranView).<br><br>During t=
he last six hours, the colour has changed from red to green, indicating a 1=
20=C2=B0 delay. This Looks like the carrier&nbsp;is ~ 20 uHz below 82 Hz (-=
0.25 ppm, quite a large difference on a relative scale).&nbsp;I am asking m=
yself how it the transmit frequency is physically being steered, possibly "=
Alexanderson-style" by&nbsp;setting the velocity of a rotating machine?&nbs=
p;If&nbsp;the frequency offset turns out to be real and stable, it could be=
 a means for DX'ers to differentiate&nbsp;the real ZEVS signal from possibl=
e local receiver artifacts.&nbsp;I wonder whether anyone else could&nbsp;ve=
rify the offset?<br><br>On the other hand, I wouldn't yet&nbsp;rule out a d=
iurnal&nbsp;propagation effect, even though at a distance of&nbsp;less than=
 a wavelength this should not produce such a&nbsp;large&nbsp;phase change. =
There could also be local&nbsp;effects on the receive site from variable hu=
midity in the vegetation near the E-field probe.&nbsp;<br><br>So the big qu=
estion is whether&nbsp;or not the phase trend will continue tonight and tom=
orrow.<br><br>Best 73,<br>Markus (DF6NM)<br></div></div>
</div></div>
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