Return-Path: Received: from rly-ma07.mx.aol.com (rly-ma07.mail.aol.com [172.20.116.51]) by air-ma07.mail.aol.com (v125.7) with ESMTP id MAILINMA073-8bc4aee06f7215; Sun, 01 Nov 2009 17:09:16 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-ma07.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMA076-8bc4aee06f7215; Sun, 01 Nov 2009 17:08:57 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N4iaf-0002WW-OO for rs_out_1@blacksheep.org; Sun, 01 Nov 2009 22:08:01 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N4iaf-0002WN-1k for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2009 22:08:01 +0000 Received: from smtp824.mail.ird.yahoo.com ([217.146.188.234]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1N4iZ7-0002yI-Ek for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2009 22:06:26 +0000 Received: (qmail 82048 invoked from network); 1 Nov 2009 22:07:54 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=IHdRtTVh5Ld1VBU01LItBLVoAN8ZS8roH+5Nuc/6G61m4gW+WODbvPfudJfkEiFgAhcx8KL7sChk5HsMDzllB+H7PpzhO6+NeC+cJh/PEneNPU1ugOOWy3A9NShqEeevGJSjCXfDu6mE8u4adR0llLYVYo2jKai5WOJNWQ3K+O8= ; Received: from unknown (HELO JimPC) (james.moritz@86.176.86.179 with login) by smtp824.mail.ird.yahoo.com with SMTP; 1 Nov 2009 22:07:53 -0000 X-Yahoo-SMTP: qKIhhNCswBB2TTHr2BORWcGGR2mpopxhCcunGIxpCKQYiG07Q7UOhNo- X-YMail-OSG: 98iaJrUVM1mrd9e3HGAYKgvUAVxXAaCH.aJ9c6wdB7sdlZ1JapsFmBL.LOeWgwVw0djoUxeKjk7depRxBPGDdNnrjPHEAK9ekU9J8teZx2Fm.ZPXVwlfreMpxax74kQ8HQ0AtlpqEazZorIJF2n.aV9Z3nPyPh1ecY5pLbc0T_AlVQX7x9hfe8ELLBgIJ5WtsflA6J2EAm2TJWSFcpFvPl7S13VlO3t2NyZygm_tmYL.huexfJ0fPbs50l7_7no2x0DrEZfkpe.UE6QKmUI2EG5r354d7qj1Dspz X-Yahoo-Newman-Property: ymail-3 Message-ID: <4F89D5F0D43E42F9B344F909CACE0ECD@JimPC> From: "James Moritz" To: References: <9afca2640910310528p4f07557aifdc0557a68bfeff8@mail.gmail.com> <004501ca5a35$30eff840$0900a8c0@lark> In-Reply-To: <004501ca5a35$30eff840$0900a8c0@lark> Date: Sun, 1 Nov 2009 22:07:53 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18005 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18005 X-Karma: unknown: DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: Re: 500kHz attenuation graphs? Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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=0.1 required=5.0 tests=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-IP: 193.82.116.20 Dear Alan, LF Group, G3NYK wrote: > Generally at LF the skywave starts to equal or exceed the > groundwave strength at ranges exceeding 700km. It may be a little less > that > that at 500k. ...And yet, when I watch the signal level of G4JNT's WSPR beacon at night, I see short duration deep fades of 20 - 30 dB quite often, and sometimes enhancements over the daytime level of several dB also. During the day, the signal level shows very little variation. So even at a distance of about 120km, it would seem the ground wave an sky wave strengths must be comparable, in order to produce the fades. Cheers, Jim Moritz 73 de M0BMU