Return-Path: Received: from mtain-mb02.r1000.mx.aol.com (mtain-mb02.r1000.mx.aol.com [172.29.96.22]) by air-di07.mail.aol.com (v129.4) with ESMTP id MAILINDI072-eacf4cbae1bc3b7; Sun, 17 Oct 2010 07:45:00 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 361633800009D; Sun, 17 Oct 2010 07:44:59 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P7Re7-0007Hy-GW for rs_out_1@blacksheep.org; Sun, 17 Oct 2010 12:43:23 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P7Re6-0007Hp-TF for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 12:43:22 +0100 Received: from mout8.freenet.de ([195.4.92.98]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P7Re5-00018E-Jl for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 12:43:22 +0100 Received: from [195.4.92.11] (helo=1.mx.freenet.de) by mout8.freenet.de with esmtpa (ID dl4yhf@freenet.de) (port 25) (Exim 4.72 #3) id 1P7Re4-00084r-CO for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 13:43:20 +0200 Received: from blfd-5d820782.pool.mediaways.net ([93.130.7.130]:3282 helo=[192.168.0.101]) by 1.mx.freenet.de with esmtpsa (ID dl4yhf@freenet.de) (TLSv1:CAMELLIA256-SHA:256) (port 465) (Exim 4.72 #3) id 1P7Re3-0004OV-RF for rsgb_lf_group@blacksheep.org; Sun, 17 Oct 2010 13:43:20 +0200 Message-ID: <4CBAE155.6030500@freenet.de> Date: Sun, 17 Oct 2010 13:43:17 +0200 From: wolf_dl4yhf User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.9) Gecko/20100915 Thunderbird/3.1.4 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <8CD38567F4B0C6A-1C1C-116D@webmail-m021.sysops.aol.com> <2C4BE56C4BAB4EB984EBC865A2BBC338@Black> In-Reply-To: <2C4BE56C4BAB4EB984EBC865A2BBC338@Black> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: VLF: Re: Detections of 5 microwatt transmission Content-Type: multipart/alternative; boundary="------------040807080207020504000101" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNKNOWN,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-sid: 3039ac1d60164cbae1ba70cc X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------040807080207020504000101 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Congrats Markus and Paul for this achievement ! I think you used a GPSDO with 10 kHz output on both ends - Thunderbolt, Trimble, or similar ? (still thinking about a simple but reliable, non-GPS solution using a 24/7 active MSK station, or maybe DCF77 / MSF with a soundcard running at 192 kSamples, or SDR-IQ running at 196 kSamples ). 73 and have a nice Sunday everyone, Wolf DL4YHF . 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 > 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) > --------------040807080207020504000101 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Congrats Markus and Paul for this achievement !

I think you used a GPSDO with 10 kHz output on both ends - Thunderbolt, Trimble, or similar ?

(still thinking about a simple but reliable, non-GPS solution using a 24/7 active MSK station, or maybe DCF77 / MSF with a soundcard running at 192 kSamples, or SDR-IQ running at 196 kSamples ).

73 and have a nice Sunday everyone,
   Wolf  DL4YHF .

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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