Return-Path: Received: from mtain-di10.r1000.mx.aol.com (mtain-di10.r1000.mx.aol.com [172.29.64.14]) by air-mf03.mail.aol.com (v127_r1.1) with ESMTP id MAILINMF034-8be44b8666de373; Thu, 25 Feb 2010 07:02:39 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-di10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7ECBD380000A3; Thu, 25 Feb 2010 07:02:37 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NkcPc-0002uw-8G for rs_out_1@blacksheep.org; Thu, 25 Feb 2010 12:01:48 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NkcPb-0002un-TL for rsgb_lf_group@blacksheep.org; Thu, 25 Feb 2010 12:01:47 +0000 Received: from mx.omskcity.com ([79.133.160.2]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NkcPZ-00044B-3N for rsgb_lf_group@blacksheep.org; Thu, 25 Feb 2010 12:01:47 +0000 Received: from noname.nodomain.nowhere (host209.161-133-79.sotline.ru [79.133.161.209]) by mx.omskcity.com (8.13.6/8.13.6) with ESMTP id o1PC1fVK065163 for ; Thu, 25 Feb 2010 18:01:42 +0600 (OMST) (envelope-from fitec@omskcity.com) Received: from localhost (fitec@localhost) by noname.nodomain.nowhere (8.8.5/8.8.5) with SMTP id TAA00350 for ; Thu, 25 Feb 2010 19:06:45 GMT X-Authentication-Warning: noname.nodomain.nowhere: fitec owned process doing -bs Date: Thu, 25 Feb 2010 19:06:45 +0000 (GMT) From: "Alexander S. Yurkov" To: rsgb_lf_group@blacksheep.org In-Reply-To: Message-ID: MIME-Version: 1.0 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.1.8 (mx.omskcity.com [79.133.160.2]); Thu, 25 Feb 2010 18:01:43 +0600 (OMST) X-Spam-Score: 1.5 (+) X-Spam-Report: autolearn=disabled,DATE_IN_FUTURE_06_12=1.498 Subject: Re: LF: AW: 9 Dreamers Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.9 required=5.0 tests=DATE_IN_FUTURE_06_12 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: 3039ac1d400e4b8666dd18d7 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) > >From a curve in an old 1981 copy of "Reference Data for Radio Engineers" , > at 10kHz (lowest value shown) atmospheric noise is given as being in the in > the range 155 to 175 dB kToB. This will have risen over the intervening > years due to the proliferation of industrial / domestic electrical > junk-noise, so if just we take the upper figure it shouldn't be outrageous > to start with. > > In a reference 1Hz bandwidth kTB = -174dBm, into a theoretical 0dBi > antenna. Therefore, you could expect to see about 0dBm, or about 1mW of > noise from such a beast Why? It is for 175 dB noise level, not for lowest 155 dB level. > > To get the V/m value from this, first calculate the effective area of a 9kHz > isotropic antenna : > At 9kHz, lambda = 33333m, G = 4.pi.A/lambda^2, G = 1, so A = > 88*10^6 m^2 > > 1mW of noise per Hz bandwidth, received in this aperture means noise density > Nd = is 1.1E-11 W/m^2 > Field strength E volts/metre, == SQRT(Nd. 377) > = 65uV/m in 1 Hz bandwidth, or 65uV/ (ROOT Hz) For 155 dB it changes to 6.5 uV/m in 1 Hz. In 0.01 Hz (QRSS100) it yelds 0.65 uV/m. 2.5 uV/m is ~10 dB over noise. Right? Regards, Alexander/RA9MB