Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1D62138000087; Mon, 21 Jan 2013 17:07:25 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1TxPVM-0007t3-Ts for rs_out_1@blacksheep.org; Mon, 21 Jan 2013 22:06:12 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1TxPVM-0007su-8z for rsgb_lf_group@blacksheep.org; Mon, 21 Jan 2013 22:06:12 +0000 Received: from mail-qa0-f48.google.com ([209.85.216.48]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1TxPVJ-0004Z3-FF for rsgb_lf_group@blacksheep.org; Mon, 21 Jan 2013 22:06:11 +0000 Received: by mail-qa0-f48.google.com with SMTP id l8so4914792qaq.7 for ; Mon, 21 Jan 2013 14:05:47 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:date:message-id:subject:from:to :content-type; bh=SLW149c8vmasNaHZhKIFsVbz9tGeLNKjT50NtfY+IIg=; b=qVMlTVa5LTjyR4He886+VPM9ojEHzGzRhShG8WpILOldt7nugtToOUwmv5LUCTd3bW ww2r/TTNQGAtoNCvLPkFuWUyUs6T7bDKbX9p5dnYF9P2M9iwffaCO/Ji6Ylhew8pzd5Y oaAV45UDFnCEVOF6BH94hSQFlWyxGYUhejzoOFB1AobANsVRvjflHGQx5kS5OC7ZTo66 nJdvOt13GPHCi5bxXxh1Za6FE8OMF90m+CnQKRSBFbQmiS+0WtU1bZOHf+tCDOr3Vhyq XoC6cNwUvbN+sX7ix62LCrMJBGziCOfQmNJOXen0ZGyUme5+YsxkjcEjD14oIo1fy+iV Pf6w== MIME-Version: 1.0 X-Received: by 10.229.203.28 with SMTP id fg28mr1170899qcb.103.1358805946898; Mon, 21 Jan 2013 14:05:46 -0800 (PST) Received: by 10.229.156.18 with HTTP; Mon, 21 Jan 2013 14:05:46 -0800 (PST) Date: Mon, 21 Jan 2013 22:05:46 +0000 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@yahoogroups.co.uk, "rsgb_lf_group@blacksheep.org" X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: With several repeatable ground wave reports on 472kHz WSPR using my 20m baseline earth-electrode antenna today, I decided it was time for a recalculation of my ERP based on a formula (for 500kHz) supplied some years ago by *Jim M0BMU*. The assumption (from M0BMU, that I am now unsure is right) is that the noise floor is around 3uV/m in a 2500Hz (WSPR) bandwidth. So, based on the WSPR S/N ratio the field strength when using the earth-electrodes can be calculated. [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.216.48 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (rogerlapthorn[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 84016abdd353c82964b6d256164a353f Subject: LF: 472kHz ERP calculations based on WSPR results Content-Type: multipart/alternative; boundary=0050450166f5c89a6f04d3d3a9d6 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=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-SCOLL-AUTHENTICATION: mtain-mk03.r1000.mx.aol.com ; domain : gmail.com DKIM : fail x-aol-sid: 3039ac1d618750fdbc1c6b76 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0050450166f5c89a6f04d3d3a9d6 Content-Type: text/plain; charset=ISO-8859-1 With several repeatable ground wave reports on 472kHz WSPR using my 20m baseline earth-electrode antenna today, I decided it was time for a recalculation of my ERP based on a formula (for 500kHz) supplied some years ago by *Jim M0BMU*. The assumption (from M0BMU, that I am now unsure is right) is that the noise floor is around 3uV/m in a 2500Hz (WSPR) bandwidth. So, based on the WSPR S/N ratio the field strength when using the earth-electrodes can be calculated. *G3ZJO* at 79km gets me at around -19dB giving my field strength around 355nV/m. *G3XDV* at 61km he gets me around -12dB S/N giving my field strength around 810nV/m. *M0BMU* at 69km he gets me around -30dB S/N giving a field strength around 100nV/m *ERP Calculations* (NB the earth-electrode antenna behaves like a loop so has directionality that has not been considered) ERP using G3ZJO's results = (E*d)^2/49; with E = 355nV, d = 79km *ERP = 16uW* ERP using G3XDV's results = (E*d)^2/49; with E = 810nV, d = 61km* **ERP = 49uW* ERP using M0BMU's results = (E*d)^2/49; with E =100nV, d = 69km* **ERP = 1uW* Now, to me these figures seem *far* too low, so perhaps the noise level is much higher than 3uV/m or my maths are wrong? Certainly the noise floor here is S4- S8 due to SMPSUs and other noise sources, so higher than 3uV/m. I think these ERP numbers can be doubled based on ground wave losses but, even so, the figures appear to be *extremely* low. My Marconi antenna is some 8dB (average) better than the earth-electrode antenna and I am sure the ERP is well above 1mW using this antenna. My RF *into* the earth electrodes is 10W. *Conclusions* I am totally puzzled: measuring antenna current on the Marconi I get ERPs that are an order of magnitude higher yet measured results with the earth-electrode antenna average just 8dB down on the Marconi. This suggests ERPs for the earth-electrode antenna in the low mW region, which I find much more believable. My maths has never been good, so it is possible I have made mistakes, so I would welcome any corrections. For now, I am of the view that the ERP is around 5mW for the earth-electrode antenna and around 30mW with the Marconi, yet measured results suggest much less. Any thoughts please? 73s Roger G3XBM -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk https://sites.google.com/site/sub9khz/ http://qss2.blogspot.com/ http://www.youtube.com/user/G3XBM --0050450166f5c89a6f04d3d3a9d6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
With several repeatable ground wave reports on 472kHz= WSPR using my 20m baseline=20 earth-electrode antenna today, I decided it was time for a recalculation of= my ERP based=20 on a formula (for 500kHz) supplied some years ago by Jim M0BMU.=A0 T= he=20 assumption (from M0BMU, that I am now unsure is right) is that the=20 noise floor is around 3uV/m in a 2500Hz (WSPR) bandwidth. So, based on=20 the WSPR S/N ratio the field strength when using the earth-electrodes=20 can be calculated.

G3ZJO at 79km gets me at around -19dB giving my field stre= ngth around 355nV/m.=A0
G3XDV at 61km he gets me around -12dB S/N= giving my field strength around 810nV/m.=A0=A0
M0BMU at 69km he = gets me around -30dB S/N giving a field strength around 100nV/m

ERP Calculations=A0 (NB the earth-electrode antenna behaves l= ike a loop so has directionality that has not been considered)

ERP using G3ZJO's results =3D (E*d)^2/49; with E =3D 355= nV, d =3D 79km =A0 ERP =3D 16uW
ERP using G3XDV's resu= lts =3D (E*d)^2/49; with E =3D 810nV, d =3D 61km=A0 ERP=A0 =3D= 49uW
ERP using M0BMU's results =3D=A0 (E*d)^2/49; with E =3D100nV, d =3D 69k= m=A0 ERP =3D 1uW

Now, to me these figures seem far too low, so perhaps the noise=20 level is much higher than 3uV/m or my maths are wrong?

Certainly th= e noise floor here is S4- S8 due to SMPSUs and other noise sources, so high= er than 3uV/m.=A0

I=20 think these ERP numbers can be doubled based on ground wave losses but, eve= n so, the figures appear to be extremely low.=A0 My Marconi antenna i= s some 8dB (average) better than the earth-electrode antenna and I am sure the ERP is well above 1mW using this antenna. My RF into the earth elec= trodes is 10W.

Conclusions
I am totally puzzled: measuring antenna current on the Marconi I get=20 ERPs that are an order of magnitude higher yet measured results with the earth-electrode antenna average just 8dB down on the Marconi. This=20 suggests ERPs for the earth-electrode antenna in the low mW region,=20 which I find much more believable. My maths has never been good, so it is p= ossible I have made mistakes, so I would welcome any corrections.

For now, I am of the view that the ERP is around 5mW for the earth-electrod= e antenna and around 30mW with the Marconi, yet measured results suggest mu= ch less.

Any thoughts please?

73s
Roger G3XBM
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