Return-Path: Received: from mtain-ma06.r1000.mx.aol.com (mtain-ma06.r1000.mx.aol.com [172.29.96.14]) by air-de03.mail.aol.com (v127_r1.1) with ESMTP id MAILINDE033-5eac4b9c003eb1; Sat, 13 Mar 2010 16:14:39 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 31CE7380000A1; Sat, 13 Mar 2010 16:14:37 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NqYeN-0006U9-Qu for rs_out_1@blacksheep.org; Sat, 13 Mar 2010 21:13:35 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NqYeN-0006U0-Ca for rsgb_lf_group@blacksheep.org; Sat, 13 Mar 2010 21:13:35 +0000 Received: from imr-db03.mx.aol.com ([205.188.91.97]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NqYeK-0004Ah-Cc for rsgb_lf_group@blacksheep.org; Sat, 13 Mar 2010 21:13:35 +0000 Received: from mtaout-ma06.r1000.mx.aol.com (mtaout-ma06.r1000.mx.aol.com [172.29.41.6]) by imr-db03.mx.aol.com (8.14.1/8.14.1) with ESMTP id o2DLDNjE016675 for ; Sat, 13 Mar 2010 16:13:23 -0500 Received: from Black (g229243009.adsl.alicedsl.de [92.229.243.9]) by mtaout-ma06.r1000.mx.aol.com (WebSuites/MUA Thirdparty client Interface) with ESMTPA id 3D9E6E00008D for ; Sat, 13 Mar 2010 16:13:23 -0500 (EST) Message-ID: <82C26C923BE747C4BD44D4FB9579E742@Black> From: "Markus Vester" To: References: In-Reply-To: Date: Sat, 13 Mar 2010 22:13:20 +0100 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-aol-global-disposition: G x-aol-sid: 3039ac1d29064b9bfff32e19 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: 8.97 kHz Grabber online Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01CAC2FA.63E7AB20" 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_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: 3039ac1d600e4b9c003d29f4 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_000B_01CAC2FA.63E7AB20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dear LF, today I have slowed down the 8.97 kHz grabber and reduced the FFT band= width down to 3.8 mHz. As expected, the noise level decreased by 6 dB= (even though the detection threshold for a dash of given duration wil= l probably have improved only by 3 dB, due to the tradeoff between inc= oherent and coherent averaging). Soundcard crystal temperature instabi= lity is just starting to become an issue, with the Alpha lines going= down a couple of bins when I open the window. The dominating noise source at this location seem to be railway overhe= ad lines, 400 meters from here. They produce a dense and audible carpe= t of variable 16.6 Hz multiples up to about 8 kHz, with some significa= nt enery up to about 12 kHz. I will attempt to run the grabber from an= other location sometime next week, using mobile internet access. BTW I was stunned to find a little knot on each of the Alpha lines, ju= st before 21 UT every evening. This must be the daily phase adjustment= mentioned by Trond Jacobsen: http://www.vlf.it/alphatrond/alpha.htm . Best wishes, MArkus (DF6NM) ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, March 07, 2010 4:50 PM Subject: 8.97 kHz Grabber online Dear LF, many thanks to the group, for the nice and positive feedback regardi= ng the recent 9 kHz experiments! I have now lashed up a temporary VLF grabber, featuring 15 mHz FFT= resolution around 8970 Hz:=20 http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm Sensitivity still leaves a bit to be desired, with a number of local= noise sources around. I won't be able to leave it on permanently due= to limited computing resources, and I will have to disconnect it duri= ng LF transmit activity. Best regards Markus ------=_NextPart_000_000B_01CAC2FA.63E7AB20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dear LF,
 
today I have slowed down the 8.97 kHz= grabber and=20 reduced the FFT bandwidth down to 3.8 mHz. As expected, the noise= level=20 decreased by 6 dB (even though the&= nbsp;detection=20 threshold for a dash of given duration will probably have improved onl= y by 3 dB,=20 due to the tradeoff between incoherent and coherent averagin= g).=20 Soundcard crystal temperature instability is just starting to become= an issue,=20 with the Alpha lines going down a couple of bins when I open= the=20 window.
 
The dominating noise source at this= location seem=20 to be railway overhead lines, 400 meters from here. They produce= a=20 dense and audible carpet of variable 16.6 Hz multiples up to abou= t 8 kHz,=20 with some significant enery up to about 12 kHz. I will attem= pt to run=20 the grabber from another location sometime next week, using mobile int= ernet=20 access.
 
BTW I was stunned to find a little kn= ot on each of=20 the Alpha lines, just before 21 UT every evening. This must be&nb= sp;the=20 daily phase adjustment mentioned by Trond Jacobsen:
 
Best wishes,
MArkus (DF6NM)
----- Original Message -----
Sent: Sunday, March 07, 2010= 4:50=20 PM
Subject: 8.97 kHz Grabber onl= ine

Dear LF,
 
many thanks to the group, for= the nice and=20 positive feedback regarding the recent 9 kHz experiments!
 
I have now lashed up a temporary VL= F grabber,=20 featuring 15 mHz FFT resolution around 8970 Hz:
Sensitivity still leaves a bit to= be desired,=20 with a number of local noise sources around. I won't be able to leav= e it on=20 permanently due to limited computing resources, and I will have to= disconnect=20 it during LF transmit activity.
 
Best regards
Markus
 
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