Return-Path: Received: (qmail 11371 invoked from network); 8 Apr 2003 14:09:53 -0000 Content-Transfer-Encoding: 8bit Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 8 Apr 2003 14:09:53 -0000 Received: (qmail 5906 invoked by uid 10001); 8 Apr 2003 14:09:51 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 8 Apr 2003 14:09:51 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 192tif-0003Ew-KP for rsgb_lf_group-outgoing@blacksheep.org; Tue, 08 Apr 2003 15:05:01 +0100 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 192tiZ-0003El-5o for rsgb_lf_group@blacksheep.org; Tue, 08 Apr 2003 15:04:55 +0100 Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 192tiS-0006Z1-00 for rsgb_lf_group@blacksheep.org; Tue, 08 Apr 2003 15:04:48 +0100 Received: from [147.197.232.252] (helo=rsch-15.herts.ac.uk) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 192tiH-0003KT-00 for rsgb_lf_group@blacksheep.org; Tue, 08 Apr 2003 15:04:37 +0100 Message-ID: <5.1.0.14.0.20030408141524.024ddd90@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Tue, 08 Apr 2003 15:04:28 +0100 To: rsgb_lf_group@blacksheep.org From: "James Moritz" In-reply-to: <5.1.0.14.0.20030408102406.02f05cd0@u0019445.kuleuven.be> References: <5.1.0.14.0.20030407151723.00a9ea90@gemini.herts.ac.uk> <191xgH-175wvYC@fwd10.sul.t-online.com> <5.1.0.14.2.20030404222503.009f79d0@mail.pncl.co.uk> MIME-Version: 1.0 X-MailScanner: No Virus detected Subject: Re: LF: Doppler shift Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-22.9 required=5.0tests=EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES,REPLY_WITH_QUOTESversion=2.51 X-Spam-Checker-Version: SpamAssassin 2.51 (1.174.2.5-2003-03-20-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Dear Rik, LF Group, At 10:30 08/04/2003 +0200, you wrote: >A friend of mine is interested in QRSS tests on 10.1MHz (30 meter) and one >of the things we are discussing is the longest useable dotlength is on >that frequency. Apart from TX (and RX) stabilty doppler shift due to >ionospheric refections will cause frequency instability Based on the experience of receiving the US "Hifer" beacons on about 13.55MHz last year, doppler shift of a few Hz can be expected - sometimes the traces are blurred, or even split into 2 separate traces a few Hz apart, but QRSS3 seems to work fairly well - I suspect a dot length longer than 3s would be counter-productive due to the generally much greater doppler effects at HF, and the rapid fading. The Hifers were often visible last summer during the night, and occasionally even audible using a dipole receiving antenna. I think they normally run a few mW into ground-plane type antennas, which is a nice demonstration of how much easier HF is! Cheers, Jim Moritz 73 de M0BMU