Return-Path: Received: from mtain-ma02.r1000.mx.aol.com (mtain-ma02.r1000.mx.aol.com [172.29.96.10]) by air-de04.mail.aol.com (v129.4) with ESMTP id MAILINDE042-5eaf4cbc817f3e3; Mon, 18 Oct 2010 13:18:55 -0400 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id C97AF38000131 for ; Mon, 18 Oct 2010 13:18:54 -0400 (EDT) Received: from uucp by elvis.franken.de with local-rmail (Exim 3.36 #1) id 1P7tML-0000h0-00; Mon, 18 Oct 2010 19:18:53 +0200 Received: from [192.168.1.12] (uhrenpc [192.168.1.12]) by mbsks.zwiebeltuete.com (Postfix) with ESMTP id 587D1448040; Mon, 18 Oct 2010 19:08:43 +0200 (CEST) Message-ID: <4CBC7F08.30206@mbsks.franken.de> Date: Mon, 18 Oct 2010 19:08:24 +0200 From: Roland Bruestle User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.8) Gecko/20100802 Thunderbird/3.1.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org CC: Markus Vester , paul , =?ISO-8859-1?Q?Stefan_Sch=E4fer?= , Renato Romero Subject: Re: VLF: Re: Detections of 5 microwatt transmission References: <8CD38567F4B0C6A-1C1C-116D@webmail-m021.sysops.aol.com> <2C4BE56C4BAB4EB984EBC865A2BBC338@Black> In-Reply-To: <2C4BE56C4BAB4EB984EBC865A2BBC338@Black> Content-Type: multipart/alternative; boundary="------------040500080507070709070806" x-aol-global-disposition: G x-aol-sid: 3039ac1d600a4cbc817e689d X-AOL-IP: 193.175.24.41 X-AOL-SPF: domain : mbsks.franken.de SPF : none X-Mailer: Unknown (No Version) --------------040500080507070709070806 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Hallo Markus, herzlichen Gl=FCckwunsch zu deinem gr=FC=DFen Erfolg. Gr=FC=DFe Roland DL3NDR Am 17.10.2010 12:56, schrieb Markus Vester: > Dear LF, > I am very happy to announce that Paul Nicholson in Todmorden was=20 > clearly able to detect each of my three test transmissions. His=20 > detailed and most interesting report is at > http://abelian.org/vlf/mv101009/ > Hats off to Paul for his outstanding achievement! > Best regards, > Markus > > ----- Original Message ----- > *From:* Markus Vester > *To:* rsgb_lf_group@blacksheep.org > > *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 > receiving 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, > and both dashes are still visible in the QRN minima on his 47uHz > grabber window > http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html > This was the intended purpose of the experiment, and a nice > counterpart 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-derived reference, the dashes appeared about two > pixels low - perhaps due to a very minute rounding error in > SpecLab's frequency scale display. > - To my utter surprise, Paul Nicholson (Todmorden, 1030.5 > km) produced 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 > whether this is a significant positive detection. Except for a > known central artifact on 8970, the highest peak appears in the > correct frequency bin in both spectra. Naively, one could then > propose that the probability 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 > Saturday (0.3% false detection rate), and 2 sigma in the higher > noise on Sunday (5%), giving a combined false positive probability > of 1 in 6667. > 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 for the slightly higher distance, would > theoretically result in 24 dB less 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 > experiment in the near future for additional confirmation. > Very many thanks to all involved in this work! > 73, Markus (DF6NM) > --------------040500080507070709070806 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hallo Markus,
herzlichen Glückwunsch zu deinem grüßen Erfolg.

Grüße
Roland DL3NDR


Am 17.10.2010 12:56, schrieb Markus Vester:
Dear LF,
 
I am very happy to announce that Paul Nicholson in Todmorden was clearly able to detect each of my three test transmissions. His detailed and most interesting report is at
 
 
Hats off to Paul for his outstanding achievement!
 
Best regards,
Markus
----- Original Message -----
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 receiving 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, and both dashes are still visible in the QRN minima on his 47uHz grabber window
 
 
This was the intended purpose of the experiment, and a nice counterpart 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-derived reference, the dashes appeared about two pixels low - perhaps due to a very minute rounding error in SpecLab's frequency scale display.
 
- To my utter surprise, Paul Nicholson (Todmorden, 1030.5 km) produced 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 whether this is a significant positive detection. Except for a known central artifact on 8970, the highest peak appears in the correct frequency bin in both spectra. Naively, one could then propose that the probability 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 Saturday (0.3% false detection rate), and 2 sigma in the higher noise on Sunday (5%), giving a combined false positive probability of 1 in 6667.
 
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 for the slightly higher distance, would theoretically result in 24 dB less 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 experiment in the near future for additional confirmation.
 
Very many thanks to all involved in this work!
 
73, Markus (DF6NM)

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