Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4F60D38000143; Tue, 3 Apr 2012 11:18:01 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SF4r7-0000Kj-1D for rs_out_1@blacksheep.org; Tue, 03 Apr 2012 15:37:09 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SF4r6-0000Ka-FI for rsgb_lf_group@blacksheep.org; Tue, 03 Apr 2012 15:37:08 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1SF4r4-0000Lc-Uo for rsgb_lf_group@blacksheep.org; Tue, 03 Apr 2012 15:37:08 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id q33Eb5dH024185 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 3 Apr 2012 16:37:05 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id q33Eb5Jb002792 for ; Tue, 3 Apr 2012 16:37:05 +0200 Message-ID: <4F7B0AF3.9010700@iup.uni-heidelberg.de> Date: Tue, 03 Apr 2012 16:36:35 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <204158566A164D98BA02A36F656764DE@acer> <4F79EE71.3030304@iup.uni-heidelberg.de> In-Reply-To: <4F79EE71.3030304@iup.uni-heidelberg.de> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: 0...36 kHz recording, 4 hours from a quiet location Content-Type: multipart/alternative; boundary="------------060406040308070203040003" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE autolearn=no version=2.63 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-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:472777952:93952408 x-aol-sid: 3039ac1d40494f7b14a971de X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------060406040308070203040003 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id q33Eb5dH024185 Hi Henny, VLF, I run various reprocessings from the yesterdays 4 hour recording (abt=20 10...14 UTC). To get an overview, this is the wideband spectrogram=20 http://dl.dropbox.com/u/19882028/VLF/wide.jpg Looks good i find. The difference of the lower cutoff frequency when=20 changing the RC highpass is here:=20 http://dl.dropbox.com/u/19882028/VLF/Comp.jpg Very odd, the levels in=20 the higher VLF are changing too, a slight decrease, although the=20 resistance is higher. Has someone ann explanation for that effect? A spectrogram of the ULF range=20 http://dl.dropbox.com/u/19882028/VLF/ULF.jpg and ELF=20 http://dl.dropbox.com/u/19882028/VLF/ELF.jpg For comparison, the spectrogram of my grabber in the city, covering the=20 same time http://dl.dropbox.com/u/19882028/VLF/widebandcity.jpg The=20 sferics appear stronger, i.e. have a higher S/N while they seem to be=20 lost in the noise on the /p location and antenna. The antenna is the=20 same design (except the 1 MOhm resistor) as in the city and the MSKs=20 appear at good strength too. Has someone an explanation? May this resistor generate noise or where is=20 the high noise floor coming from? I also thought about microphonic=20 effects... Unfortunately there was no detection of PA3CPM in "600" and in "6000",=20 http://dl.dropbox.com/u/19882028/VLF/600.jpg=20 http://dl.dropbox.com/u/19882028/VLF/6000.jpg Maybe due to the same reaco= n. Why does the same design produce good results in the city but not in the=20 forest? Where is the noise coming from? Why does G3ZJO clearly receive=20 ZEVS at 82 Hz with this design but not i ? I'll go on testing, investigating and playing :-) 73, Stefan/DK7FC Am 02.04.2012 20:22, schrieb Stefan Sch=E4fer: > Hi Henny, VLF > > Thanks for your transmission. > It was a nice day and i took a 4 hour recording during climbing on=20 > trees, sleeping and eating in a hammok :-) > Right now i'm running various reprocessings and hope to find your=20 > signal out of the noise. I will post screenshots of the complete=20 > session later. > > If someone wants to play with the recording wav file, it is available=20 > at=20 > http://dl.dropbox.com/u/19882028/LF/audio/EfieldSteinbruchOhne5k6ExtAkk= u.WAV=20 > for a while. It is a 1.95 GB file sampled at 72 k/s. > > I switched a 1 MOhm resistor in series to the 5k6 resistor of my=20 > active receive antenna. The 5k6 resistor should form a high pass with=20 > the 10 nF capacitor in the circuit=20 > (http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20f= ield%20antenna%20by%20DK7FC.jpg)=20 > By adding the 1 MOhm resistor in series it was clearly seen that the=20 > lower cut off frequency dropped to < 1 kHz. The highpass was intended=20 > to reduce mains hum and all the stuff below 4 kHz but there in the=20 > forest, this is no problem :-) > > 73, Stefan/DK7FC > > PS: On my VLF grabber in the city i see a trace at 8970.002 Hz, maybe=20 > this was DF6NM transmitting a test signal too? > > Am 02.04.2012 10:11, schrieb henny van elst: >> Gm Stefan,lf >> the tx is on,8.970 Khz >> henny cpm >> 73's --------------060406040308070203040003 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Henny, VLF,

I run various reprocessings from the yesterdays 4 hour recording (abt 10...14 UTC). To get an overview, this is the wideband spectrogram http://dl.dropbox.com/u/19882028/VLF/wide.jpg
Looks good i find. The difference of the lower cutoff frequency when changing the RC highpass is here: http://dl.dropbox.com/u/19882028/VLF/Comp.jpg Very odd, the levels in the higher VLF are changing too, a slight decrease, although the resistance is higher. Has someone ann explanation for that effect?
A spectrogram of the ULF range http://dl.dropbox.com/u/19882028/VLF/ULF.jpg and ELF http://dl.dropbox.com/u/19882028/VLF/ELF.jpg
For comparison, the spectrogram of my grabber in the city, covering the same time http://dl.dropbox.com/u/19882028/VLF/widebandcity.jpg The sferics appear stronger, i.e. have a higher S/N while they seem to be lost in the noise on the /p location and antenna. The antenna is the same design (except the 1 MOhm resistor) as in the city and the MSKs appear at good strength too.
Has someone an explanation? May this resistor generate noise or where is the high noise floor coming from? I also thought about microphonic effects...

Unfortunately there was no detection of PA3CPM in "600" and in "6000", http://dl.dropbox.com/u/19882028/VLF/600.jpg http://dl.dropbox.com/u/19882028/VLF/6000.jpg Maybe due to the same reacon.

Why does the same design produce good results in the city but not in the forest? Where is the noise coming from? Why does G3ZJO clearly receive ZEVS at 82 Hz with this design but not i ?

I'll go on testing, investigating and playing :-)

73, Stefan/DK7FC


Am 02.04.2012 20:22, schrieb Stefan Schäfer:
Hi Henny, VLF

Thanks for your transmission.
It was a nice day and i took a 4 hour recording during climbing on trees, sleeping and eating in a hammok :-)
Right now i'm running various reprocessings and hope to find your signal out of the noise. I will post screenshots of the complete session later.

If someone wants to play with the recording wav file, it is available at http://dl.dropbox.com/u/19882028/LF/audio/EfieldSteinbruchOhne5k6ExtAkku.WAV for a while. It is a 1.95 GB file sampled at 72 k/s.

I switched a 1 MOhm resistor in series to the 5k6 resistor of my active receive antenna. The 5k6 resistor should form a high pass with the 10 nF capacitor in the circuit (http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna%20by%20DK7FC.jpg) By adding the 1 MOhm resistor in series it was clearly seen that the lower cut off frequency dropped to < 1 kHz. The highpass was intended to reduce mains hum and all the stuff below 4 kHz but there in the forest, this is no problem :-)

73, Stefan/DK7FC

PS: On my VLF grabber in the city i see a trace at 8970.002 Hz, maybe this was DF6NM transmitting a test signal too?

Am 02.04.2012 10:11, schrieb henny van elst:
Gm Stefan,lf
the tx is on,8.970 Khz
henny cpm
73's
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