Return-Path: Received: (qmail 23233 invoked from network); 26 Sep 2001 08:28:29 -0000 Received: from unknown (HELO warrior-inbound.services.quay.plus.net) (212.159.14.227) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 26 Sep 2001 08:28:29 -0000 Received: (qmail 6086 invoked from network); 26 Sep 2001 08:26:22 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 26 Sep 2001 08:26:22 -0000 X-Priority: 3 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15m93h-0006e3-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 26 Sep 2001 08:24:41 +0100 X-MSMail-Priority: Normal Received: from relay.dera.gov.uk ([192.5.29.49]) by post.thorcom.com with smtp (Exim 3.16 #2) id 15m93f-0006dy-00 for rsgb_lf_group@blacksheep.org; Wed, 26 Sep 2001 08:24:39 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: (qmail 31607 invoked from network); 26 Sep 2001 08:23:59 +0100 Received: from trtnmail.dera.gov.uk (146.80.9.56) by relay.dera.gov.uk with SMTP; 26 Sep 2001 08:23:59 +0100 Received: (qmail 20764 invoked from network); 26 Sep 2001 08:29:06 +0100 Received: (ofmipd 192.5.29.90); 26 Sep 2001 07:28:44 -0000 Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id IAA03685; Wed, 26 Sep 2001 08:31:11 +0100 (BST) Received: (qmail 25735 invoked from network); 26 Sep 2001 08:13:05 -0000 Received: from gauntlet.mail.dera.gov.uk (172.16.9.10) by baton.dera.gov.uk with SMTP; 26 Sep 2001 08:13:05 -0000 Received: by gauntlet.mail.dera.gov.uk; id HAA13847; Wed, 26 Sep 2001 07:56:05 GMT Received: from unknown(10.71.64.31) by gauntlet.mail.dera.gov.uk via smap (3.2) id xma013832; Wed, 26 Sep 01 07:55:53 GMT Received: from mailex.dera.gov.uk (unverified) by mailguard.dera.gov.uk (Content Technologies SMTPRS 4.1.5) with SMTP id for ; Wed, 26 Sep 2001 08:25:54 +0100 Received: (qmail 5350 invoked from network); 26 Sep 2001 07:09:48 +0100 Date: 26 Sep 2001 08:22:49 +0100 Message-ID: <7D653C9C42F5D411A27C00508BF8803D55C5C7@PDW-MAIL-R1> From: "Andrew Talbot" To: rsgb_lf_group@blacksheep.org X-5Received: from softdnserror (HELO cchecker.dstl.gov.uk) (192.168.248.52) by mailex.dstl.gov.uk with SMTP; 26 Sep 2001 06:09:48 -0000 X-4Received: from FRN-MAIL-R3.dstl.gov.uk (unverified) by cchecker.dstl.gov.uk (Content Technologies SMTPRS 4.1.2) with ESMTP id for ; Wed, 26 Sep 2001 07:09:00 +0100 X-3Received: by frn-mail-r3.dstl.gov.uk with Internet Mail Service (5.5.2650.21)id ; Wed, 26 Sep 2001 08:22:50 +0100 Subject: LF: RE: Doppler effect. MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/html; charset=windows-1252 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit

The rate of recombination of the E (?) layer causing the height to change at dusk / dawn will move at this sort of rate.

I did see Doppler shifts, although not perhaps quite as great as this, on the signals from Larry at least once. This is one of the mechanisms limiting the data rates we can go down to when using very low signalling rates.

A couple of years ago I made some tests receiving DCF, the German time signal, comparing its phase against a locally generated Caesium reference. The interference patterns at dusk / dawn showed fading consistent with interference between the two skywave & groundwave signals, one of which was changing at a rate consistent with this order of magnitude of velocity.

Andy G4JNT

-----Original Message-----
From: Dave Pick [mailto:g3yxm@wireless.org.uk]
Sent: 2001-09-25 18:40
To: LF Group
Subject: LF: Doppler effect.

Dear all.

I have the Argo screen-shots of ZL6QH recorded in Papua New Guinea, a path of about 4,700km. This is not very different from out trans-Atlantic tests but Ricks traces show a Doppler effect around midnight which spreads the signal over about 0.1Hz, I have never seen this on a 136k trans-Atlantic trace.

Have a look at the shots on http://www.wireless.org.uk/newspic63.htm and see what you think.

Rick has calculated that the reflecting medium would have to have a velocity of around 100m/sec, assuming a double hop, to cause this kind of shift.

Any propagation brains care to speculate on the cause of this, and is there a reason why we haven't seen it on 136?

73.

Dave.

G3YXM





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