Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v17MKaVB003364 for ; Tue, 7 Feb 2017 23:20:37 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cbE4F-0008LD-B4 for rs_out_1@blacksheep.org; Tue, 07 Feb 2017 22:16:55 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cbE4E-0008L4-Mt for rsgb_lf_group@blacksheep.org; Tue, 07 Feb 2017 22:16:54 +0000 Received: from porthos.netcom.co.uk ([217.72.171.73]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cbE4B-0004bG-Am for rsgb_lf_group@blacksheep.org; Tue, 07 Feb 2017 22:16:53 +0000 X-DKIM-Result: Domain=abelian.org Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=abelian.org ; s=default; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:To:Subject:Sender:Reply-To:Cc: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=9YiUWaOuevSNeX39kunn8A6XmetKS/zozUtTa11+Tpw=; b=A3vCddCWXekXZTZ4xi0Jy+uSFM XY0SOvz5Pnpap4lDqTJPmuxC6tzb2gS2rvqyJ+5e1jeP2SXEa/IkHzliO20+TyXXLcEfgP/bmlQn0 8qlaerw9DU+HIpKwGTRDHJoA9h2ZmqFTFba7+1o+pVidGM5IpRlZEm36rjaAbPl1jA+Y=; Received: from i-194-106-52-83.freedom2surf.net ([194.106.52.83]:43643 helo=pn.abelian.org) by porthos.netcom.co.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.88) (envelope-from ) id 1cbE4A-0005WN-16 for rsgb_lf_group@blacksheep.org; Tue, 07 Feb 2017 22:16:50 +0000 Received: from [127.0.0.1] (localhost [127.0.0.1]) by pn.abelian.org (Postfix) with ESMTP id 7145E400068 for ; Tue, 7 Feb 2017 22:16:49 +0000 (UTC) To: rsgb_lf_group@blacksheep.org References: <15a10668d0b-1a2e-a32b@webprd-a53.mail.aol.com> From: Paul Nicholson Message-ID: Date: Tue, 7 Feb 2017 22:16:49 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <15a10668d0b-1a2e-a32b@webprd-a53.mail.aol.com> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - porthos.netcom.co.uk X-AntiAbuse: Original Domain - blacksheep.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - abelian.org X-Get-Message-Sender-Via: porthos.netcom.co.uk: authenticated_id: catchall@abelian.org X-Authenticated-Sender: porthos.netcom.co.uk: catchall@abelian.org X-Scan-Signature: 290c8768709872f914a4ca71ad6bfe49 Subject: Re: VLF: 8270.0025 Hz Sunday - VLF MIMO? Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: X-Keywords: X-UID: 10508 Markus wrote: > on air since 9:25 UT: 8270.0025 Hz, 0.35 A, ~ 10 uW. > ... without interruption until 22:00 UT. Uwe wrote: > carrier of 8WX [8270.0000] is on the air agn since 1141UTC. > carier off ... 2134UTC http://abelian.org/vlf/tmp/170205a.png Markus wrote: > Uwe and I could simultaneously send two different EbNaut > messages on the same frequency, which could then be > decoded independently. This is what I expect to happen: Two different messages, same frequency, same S/N, same coding and number of chars, simultaneous symbols, will both decode, so long as their phase is different. If their received phases are 90 degrees apart, each will decode with no extra errors. As the phase difference is reduced, extra symbol errors will occur. With zero phase difference, both will still decode but with about 6dB loss. If the two transmissions used different coding or message length or symbol period, they would each decode with the other signal just adding a little to the background noise. Certainly no problem if the frequencies are slightly different. I took 9 hours 12:00 to 21:00 and ran the double carrier into ebnaut -d. Each decodes to star messages independently with constant reference phase at the expected frequency offset. Best decodes using 8K19A are: DJ8WX 21 second symbols, 26 chars, Eb/N0 = 0.2 dB DF6NM 34 second symbols, 14 chars, Eb/N0 = 0.9 dB The above with the loop aligned mid way between the two bearings. -- Paul Nicholson --