Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de06.r1000.mx.aol.com (Internet Inbound) with ESMTP id F0290380000EA; Thu, 20 Oct 2011 06:19:04 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RGph5-0002me-Ea for rs_out_1@blacksheep.org; Thu, 20 Oct 2011 11:17:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RGph5-0002mV-2U for rsgb_lf_group@blacksheep.org; Thu, 20 Oct 2011 11:17:47 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RGph4-0003Ni-4s for rsgb_lf_group@blacksheep.org; Thu, 20 Oct 2011 11:17:47 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p9KAHgSH023044 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 20 Oct 2011 12:17:44 +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 p9KAHgOp000849 for ; Thu, 20 Oct 2011 12:17:42 +0200 Message-ID: <4E9FF511.4050203@iup.uni-heidelberg.de> Date: Thu, 20 Oct 2011 12:16:49 +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: <4E9F01CB.2050302@iup.uni-heidelberg.de> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: OK2BVG_8970 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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: 0:2:424097504:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40ce4e9ff5987706 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Dimitris, Am 20.10.2011 02:20, schrieb Dimitrios Tsifakis: > I haven't given a lot of thought on the circuitry to > connect the sound card to some sort of active antenna. Are there any > suggestions on how to proceed? This is what i use on my grabber: http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna%20by%20DK7FC.jpg > Also, are you using externally clocked > soundcards? Mostly they are locked internally, i.e. by SpecLab. You have to lock on a reference frequency to correct the soundcard xtal drift. This can be done by using a small GPS module (running from the 5V of the USB) that has a 10 khz output. You can see the 10 kHz line in my wideband spectrogram on the bottom of the grabber site. Alternatively you can lock on a MSK transmitter (military) if one is available. In VK, there is NWC on 19.8 kHz which is in OG78BE (locator). You should have good reception of that transmitter since we can see it here in 1 Hz as well. > I suppose, once you get into the uHz territory, having an > external super stable clock feeding the soundcard is a must? > YES! 73, Stefan/DK7FC