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References: <PAEFLMFGBDKKCONLMLBIOELMCHAA.ganymede444@btopenworld.com> <45028DB2.2070608@xs4all.nl>
To: rsgb_lf_group@blacksheep.org
Date: Mon, 11 Sep 2006 12:39:49 -0400
In-Reply-To: <45028DB2.2070608@xs4all.nl>
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From: markusvester@aol.com
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Subject: Re: LF: Big signal with hum...
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=20
Dear LF,
=20
the "big buzzer" is on again today... it's most certainly the EFR transmitte=
r at Budapest-Lakihegy, 135.6 kHz:
http://maps.google.com/maps?f=3Dq&hl=3Dde&q=3D47+22+17+N,+19+00+22+E&ie=3DUT=
F8&z=3D18&ll=3D47.373866,19.004492&spn=3D0.003426,0.005488&t=3Dk&om=3D1
=20
Several times I could hear relatively weak sweep signals, probably generated=
 by a network analyzer used for antenna testing. Most of the high power test=
s were apparently applying a continuous 010101 sequence at 202.55 baud FSK,=20=
causing the hum-like sidebands. Reducing the receiver gain by 7 dB cleared u=
p the severe overloading effects on the LF grabber. This left a set of thin=20=
red lines spaced at 101 Hz, reaching up to about 136.7 kHz. However with rea=
l data, the sidebands will smear out and clutter the lower half of the band=20=
during the telegrams.
=20

Spectrum taken 06-09-11 6:41, 135.600 kHz at 1100 Hz.

Assuming that we will have to live with this beast, I wonder if there is a w=
ay to extract its teeth. A signal processing software could decode the data,=
 model the filter transfer function and estimate the FSK transition times. T=
hen one could generate a local replica of the signal, and use that to cancel=
 it. Seems related to a key-click filter algorithm ( http://www.dxatlas.com/=
Rocky/ ) - has anyone in the group tried to implement something similar?
=20
Kind regards
Markus, DF6NM

=20
=20
=20
-----Urspr=C3=BCngliche Mitteilung-----
Von: nl9222@xs4all.nl
An: rsgb_lf_group@blacksheep.org
Verschickt: Sa., 9.Sept.2006, 11:47
Thema: Re: LF: Big signal with hum...


Dave G3WCB wrote:=20
> Anybody else notice the ghastly big signal with 50Hz hum bars on around=20
> 135,500 kHz? It's been on and off all evening, and is on at the moment=20
> (2250z)=20
> > I thought it was local to me, but it also appears on Marcus's grabber :-=
(=20
> > 73, Dave G3WCB IO91RM=20
=20
Dave and all=20
The signal here was S9 + 50dB, "blackening" the whole band=20
See images ... if they make it here=20
Full band image still is on the grabber [time is in utc]=20
http://www.xs4all.nl/~nl9222/136grab.htm=20
=20
Hopefully this device has been selfdestructed ;-)=20
73 de Ko, NL9222=20


=20

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<HTML><BODY>
<div>

<div class=3Denvelope style=3D"FLOAT: none" align=3Dleft>&nbsp;</div>


<div><SPAN></SPAN></div>
Dear LF,</div>


<div>&nbsp;</div>


<div>the "big buzzer" is on again today... it's most certainly the EFR trans=
mitter at Budapest-Lakihegy, 135.6 kHz:<br>
<A href=3D"http://maps.google.com/maps?f=3Dq&amp;hl=3Dde&amp;q=3D47+22+17+N,=
+19+00+22+E&amp;ie=3DUTF8&amp;z=3D18&amp;ll=3D47.373866,19.004492&amp;spn=
=3D0.003426,0.005488&amp;t=3Dk&amp;om=3D1">http://maps.google.com/maps?f=3Dq=
&amp;hl=3Dde&amp;q=3D47+22+17+N,+19+00+22+E&amp;ie=3DUTF8&amp;z=3D18&amp;ll=
=3D47.373866,19.004492&amp;spn=3D0.003426,0.005488&amp;t=3Dk&amp;om=3D1</A><=
/div>


<div>&nbsp;</div>


<div>Several times I could hear relatively weak sweep signals, probably gene=
rated by a network analyzer used for antenna testing. Most of the high power=
 tests were apparently applying a continuous 010101 sequence at 202.55 baud=20=
FSK, causing the hum-like sidebands. Reducing the receiver gain by 7 dB clea=
red up the severe overloading effects on the LF grabber. This left a set of=20=
thin red lines spaced at 101 Hz, reaching up to about 136.7 kHz. However wit=
h real data, the sidebands will smear out and clutter the lower half of the=20=
band during the telegrams.</div>


<div>&nbsp;</div>


<div><A href=3D"http://fotocenter.aol.de/ap/singleImage.do?pid=3Da7b0L9M7SR*=
Aed5TdPmzdH6GnBCYBOmWXLRfv4xQp5Fd3Ig%3D"><IMG class=3DAOLInlineImage id=3DAO=
LP612396 title=3D"" style=3D"BORDER-RIGHT: #f5f5f4 1px solid; BORDER-TOP: #f=
5f5f4 1px solid; BACKGROUND-IMAGE: none; MARGIN: 5px; VERTICAL-ALIGN: middle=
; BORDER-LEFT: #f5f5f4 1px solid; BORDER-BOTTOM: #f5f5f4 1px solid" height=
=3D419 src=3D"http://links.pictures.aol.com/pic?id=3Da7b0L9M7SR*Aed5TdPmzdH6=
GnBCYBOmWXLRfv4xQp5Fd3Ig=3D&amp;size=3Dl" width=3D600></A><br>
Spectrum taken 06-09-11 6:41, 135.600 kHz at 1100 Hz.</div>


<div><br>
Assuming that we will have to live with this beast, I wonder if there is a w=
ay to extract its teeth. A signal processing software could decode the data,=
 model the filter transfer function and estimate the FSK transition times. T=
hen one could generate a local replica of the signal, and use that to cancel=
 it. Seems related to a key-click filter algorithm ( <A href=3D"http://www.d=
xatlas.com/Rocky/">http://www.dxatlas.com/Rocky/</A> ) - has anyone in the g=
roup tried to implement something similar?</div>


<div>&nbsp;</div>


<div>Kind regards</div>


<div>Markus, DF6NM</div>


<div><br>
&nbsp;</div>


<div>&nbsp;</div>
&nbsp;<br>
-----Urspr=C3=BCngliche Mitteilung-----<br>
Von: nl9222@xs4all.nl<br>
An: rsgb_lf_group@blacksheep.org<br>
Verschickt: Sa., 9.Sept.2006, 11:47<br>
Thema: Re: LF: Big signal with hum...<br>
<br>

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<div class=3DAOLPlainTextBody id=3DAOLMsgPart_1_f0d018f8-2ce4-4bea-ac8c-51ba=
edf80a08>Dave G3WCB wrote:&nbsp;<br>
&gt; Anybody else notice the ghastly big signal with 50Hz hum bars on around=
&nbsp;<br>
&gt; 135,500 kHz? It's been on and off all evening, and is on at the moment&=
nbsp;<br>
&gt; (2250z)&nbsp;<br>
&gt; &gt; I thought it was local to me, but it also appears on Marcus's grab=
ber :-(&nbsp;<br>
&gt; &gt; 73, Dave G3WCB IO91RM&nbsp;<br>
&nbsp;<br>
Dave and all&nbsp;<br>
The signal here was S9 + 50dB, "blackening" the whole band&nbsp;<br>
See images ... if they make it here&nbsp;<br>
Full band image still is on the grabber [time is in utc]&nbsp;<br>
<A href=3D"http://www.xs4all.nl/~nl9222/136grab.htm" target=3D_blank>http://=
www.xs4all.nl/~nl9222/136grab.htm</A>&nbsp;<br>
&nbsp;<br>
Hopefully this device has been selfdestructed ;-)&nbsp;<br>
73 de Ko, NL9222&nbsp;<br>
</div>
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