Return-Path: Received: from mtain-md12.r1000.mx.aol.com (mtain-md12.r1000.mx.aol.com [172.29.96.96]) by air-mb07.mail.aol.com (v129.4) with ESMTP id MAILINMB072-a7854cbad7042a3; Sun, 17 Oct 2010 06:59:16 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md12.r1000.mx.aol.com (Internet Inbound) with ESMTP id C5F3538000045; Sun, 17 Oct 2010 06:59:14 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P7QvH-00078v-2f for rs_out_1@blacksheep.org; Sun, 17 Oct 2010 11:57:03 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P7QvG-00078m-Gb for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 11:57:02 +0100 Received: from imr-ma02.mx.aol.com ([64.12.206.40]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P7QvD-0000pP-Vi for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 11:57:02 +0100 Received: from mtaout-ma05.r1000.mx.aol.com (mtaout-ma05.r1000.mx.aol.com [172.29.41.5]) by imr-ma02.mx.aol.com (8.14.1/8.14.1) with ESMTP id o9HAur7Z014337; Sun, 17 Oct 2010 06:56:53 -0400 Received: from Black (nrbg-4d073bb1.pool.mediaWays.net [77.7.59.177]) by mtaout-ma05.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 6B910E0000B9; Sun, 17 Oct 2010 06:56:48 -0400 (EDT) Message-ID: <2C4BE56C4BAB4EB984EBC865A2BBC338@Black> From: "Markus Vester" To: Cc: "paul" , =?iso-8859-1?Q?Stefan_Sch=E4fer?= , "Renato Romero" References: <8CD38567F4B0C6A-1C1C-116D@webmail-m021.sysops.aol.com> In-Reply-To: <8CD38567F4B0C6A-1C1C-116D@webmail-m021.sysops.aol.com> Date: Sun, 17 Oct 2010 12:56:31 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16669 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: VLF: Re: Detections of 5 microwatt transmission Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01CB6DFA.B83A4830" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,MISSING_OUTLOOK_NAME 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-sid: 3039ac1d60604cbad70211f0 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0007_01CB6DFA.B83A4830 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dear LF, I am very happy to announce that Paul Nicholson in Todmorden was clear= ly able to detect each of my three test transmissions. His detailed an= d most interesting report is at http://abelian.org/vlf/mv101009/ Hats off to Paul for his outstanding achievement! Best regards, Markus ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, October 12, 2010 8:57 PM Subject: VLF: Detections of 5 microwatt transmission Dear LF, for my VLF test transmissions on the last weekend (Oct 9: 8969.998= Hz, Oct. 10: 8989.997 Hz), I have received reports from three receivi= ng stations: - Walter DJ2LF near Erlangen (20.2 km) received the carrier again in= good quality, using 0.95 mHz resolution. Radiated power and received= SNR were quite similar to our two-way QSO on June 4th. - Stefan DK7FC in Heidelberg (178.5 km) reported about 10 dB SNR, an= d both dashes are still visible in the QRN minima on his 47uHz grabber= window=20 http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html This was the intended purpose of the experiment, and a nice counterp= art to the earlier detection of a 200 uW kite transmission on Aug 29th= . Even though both of us were locking the samplerate to a 10 kHz GPS-d= erived reference, the dashes appeared about two pixels low - perhaps= due to a very minute rounding error in SpecLab's frequency scale disp= lay. - To my utter surprise, Paul Nicholson (Todmorden, 1030.5 km) produc= ed two spectra, taken over the duration of the transmissions: http://abelian.org/vlf/df6nm/2010_10_09a.gif (9:50 - 18:00, 34= uHz) http://abelian.org/vlf/df6nm/2010_10_10a.gif (9:00 - 15:00, 46= uHz) After taking a deep breath, we now have to deal with the question wh= ether this is a significant positive detection. Except for a known cen= tral artifact on 8970, the highest peak appears in the correct frequen= cy bin in both spectra. Naively, one could then propose that the proba= bility of this happening at random would simply be the inverse of the= number of displayed bins, ie. around 1:230 for Saturday and 1:170 for= Sunday. Thus the combined probability of a false positive detection= on both days would seem to be only 1 in 40000. Certainly there is a= degree of arbitrariness in the choice of the display range (8 mHz). Paul estimated that the signal was about 3 standard deviations on Sa= turday (0.3% false detection rate), and 2 sigma in the higher noise on= Sunday (5%), giving a combined false positive probability of 1 in 666= 7. We can also look at the plausibility of the absolute fieldstrength= of the peaks (about 0.2 fT, equivalent to 0.06 uV/m). If I remember= correctly, Paul's first detection of Stefan's kite signal on March 15= was at about 3 fT, and Stefan was then radiating approx. 1 mW EMRP.= Scaling this down to my estimated 5 uW EMRP, and taking another dB fo= r the slightly higher distance, would theoretically result in 24 dB le= ss fieldstrength, or 0.19 fT - almost a perfect match. So by these lines, it would seem at least very likely that Paul has= indeed observed my feeble signal! We intend to do repeat the experime= nt in the near future for additional confirmation. Very many thanks to all involved in this work! 73, Markus (DF6NM) ------=_NextPart_000_0007_01CB6DFA.B83A4830 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dear LF,
 
I am very happy to announce that= Paul=20 Nicholson in Todmorden was clearly able to detect each=20 of my three test transmissions. His detailed and most intere= sting=20 report is at
 
 
Hats off to Paul for his outstanding= =20 achievement!
 
Best regards,
Markus
----- Original Message -----
Sent: Tuesday, October 12, 20= 10 8:57=20 PM
Subject: VLF: Detections of= 5 microwatt=20 transmission
=

Dear LF,
 
for my VLF test transmissions on the last weekend (Oct 9: 8969.= 998 Hz,=20 Oct. 10: 8989.997 Hz), I have received reports from three receiving= =20 stations:
 
- Walter DJ2LF near Erlangen (20.2 km) received the carrier aga= in in good=20 quality, using 0.95 mHz resolution. Radiated power and received= SNR were=20 quite similar to our two-way QSO on June 4th.
 
- Stefan DK7FC in Heidelberg (178.5 km) reported about 10 dB SN= R, and=20 both dashes are still visible in the QRN minima on his 47uHz grabber= window=20
 
 
This was the intended purpose of the experiment, and = a nice=20 counterpart to the earlier detection of a 200 uW kite transmission= on Aug=20 29th. Even though both of us were locking the samplerate to a 10 kHz= =20 GPS-derived reference, the dashes appeared about two pixels low= - perhaps=20 due to a very minute rounding error in SpecLab's frequency scale=20 display.
 
- To my utter surprise, Paul Nicholson (Todmorden, 1030.5=20 km) produced two spectra, taken over the duration of the=20 transmissions:
 
   http://abelian.org/vlf/df6nm/2010_10_09a.gif  = ;=20 (9:50 - 18:00, 34 uHz)
   http://abelian.org/vlf/df6nm/2010_10_1= 0a.gif  =20 (9:00 - 15:00, 46 uHz)
 
After taking a deep breath, we now have to deal with the questi= on whether=20 this is a significant positive detection. Except for a known central= artifact=20 on 8970, the highest peak appears in the correct frequency bin in bo= th=20 spectra. Naively, one could then propose that the probability of thi= s=20 happening at random would simply be the inverse of the number of dis= played=20 bins, ie. around 1:230 for Saturday and 1:170 for Sunday. Thus the= combined=20 probability of a false positive detection on both days would seem to= be only 1=20 in 40000. Certainly there is a degree of arbitrariness in the choice= of the=20 display range (8 mHz).
 
Paul estimated that the signal was about 3 standard deviations= on=20 Saturday (0.3% false detection rate), and 2 sigma in the higher nois= e on=20 Sunday (5%), giving a combined false positive probability of 1 in 66= 67.
 
We can also look at the plausibility of the absolute fieldstren= gth of the=20 peaks (about 0.2 fT, equivalent to 0.06 uV/m). If I remember correct= ly, Paul's=20 first detection of Stefan's kite signal on March 15 was at about 3= fT, and=20 Stefan was then radiating approx. 1 mW EMRP. Scaling this down to my= estimated=20 5 uW EMRP, and taking another dB for the slightly higher distance,= would=20 theoretically result in 24 dB less fieldstrength, or 0.19 fT - almos= t a=20 perfect match.
 
So by these lines, it would seem at least very likely that Paul= has=20 indeed observed my feeble signal! We intend to do repeat the experim= ent in the=20 near future for additional confirmation.
 
Very many thanks to all involved in this work!
 
73, Markus (DF6NM)
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