Return-Path: Received: (qmail 17496 invoked from network); 12 Apr 2002 10:32:12 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 12 Apr 2002 10:32:12 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 27618 invoked from network); 12 Apr 2002 10:32:11 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys.services.quay.plus.net with SMTP; 12 Apr 2002 10:32:11 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16vzl1-0000SB-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 12 Apr 2002 13:02:23 +0100 Received: from hestia.herts.ac.uk ([147.197.200.9]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 16vzl0-0000S6-00 for rsgb_lf_group@blacksheep.org; Fri, 12 Apr 2002 13:02:22 +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 16vyE5-0005Kv-00 for rsgb_lf_group@blacksheep.org; Fri, 12 Apr 2002 11:24:17 +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 16vyE4-0007mA-00 for rsgb_lf_group@blacksheep.org; Fri, 12 Apr 2002 11:24:17 +0100 Message-ID: <5.1.0.14.0.20020412102115.00aa0340@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Fri, 12 Apr 2002 11:18:34 +0100 To: rsgb_lf_group@blacksheep.org From: "James Moritz" Subject: Re: LF: Phase meter for propagation experiment In-reply-to: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Dear LF Group, Thinking a little more on this idea, it seems to me that using LF standard frequency signals as a phase reference has a basic flaw - the reference phase signal received at the stations taking part in the experiment will also be affected by LF propagation phenomena - there would be no easy way of separating the effects of propagation on the signal being studied from propagation effects on the reference signal. So it would seem to be essential to use a reference signal independent of LF propagation effects, such as GPS or the TV line timebase. Thanks to DJ8WX for the LF broadcast info - looking at the Droitwich signal with my vectorscope circuit some time ago, the 198kHz carrier appears to be phase modulated, but the phase deviation is only a few 10s of degrees; the carrier phase just wobbles around a mean value, which would not matter much in a measurement integrated over several seconds. Some of the other European broadcast stations have similar phase modulation. Cheers, Jim Moritz 73 de M0BMU