Delivered-To: daveyxm@virginmedia.com Received: by 10.50.208.67 with SMTP id mc3csp102335igc; Sun, 18 May 2014 05:49:54 -0700 (PDT) X-Received: by 10.152.10.40 with SMTP id f8mr362464lab.75.1400417393532; Sun, 18 May 2014 05:49:53 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com. [195.171.43.25]) by mx.google.com with ESMTP id k3si5928915lbv.248.2014.05.18.05.49.52 for ; Sun, 18 May 2014 05:49:53 -0700 (PDT) Received-SPF: none (google.com: owner-rsgb_lf_group@blacksheep.org does not designate permitted sender hosts) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: owner-rsgb_lf_group@blacksheep.org does not designate permitted sender hosts) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Wm0Vk-0004pc-WD for rs_out_1@blacksheep.org; Sun, 18 May 2014 13:48:16 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Wm0Vk-0004pH-Fc for rsgb_lf_group@blacksheep.org; Sun, 18 May 2014 13:48:16 +0100 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.82) (envelope-from ) id 1Wm0Vi-0005Nt-8J for rsgb_lf_group@blacksheep.org; Sun, 18 May 2014 13:48:15 +0100 Received: from sb.abelian.org (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by parrot.netcom.co.uk (Postfix) with ESMTP id 57BAD3273EE for ; Sun, 18 May 2014 13:45:12 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 257BF28A0191 for ; Sun, 18 May 2014 12:48:13 +0000 (UTC) Message-ID: <5378AC0C.20704@abelian.org> Date: Sun, 18 May 2014 12:48:12 +0000 From: Paul Nicholson User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <536F1A51.3060806@abelian.org> <078901cf6d1b$4179a730$c46cf590$@comcast.net> <5370FABB.8020500@abelian.org> <53711C3E.4040207@gmail.com> <53724676.20309@abelian.org> In-Reply-To: <53724676.20309@abelian.org> X-Spam-Score: 0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Another successful test by Markus DF6NM this morning, 2014-05-18. Sending 100 bits at 8270.000 Hz using a rate 1/8 convolutional code with constraint length 25. The data rate was 24.2 bits per hour and the Shannon capacity for the channel is around 28 bits per hour. [...] Content analysis details: (0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [217.72.171.49 listed in list.dnswl.org] 0.7 SPF_NEUTRAL SPF: sender does not match SPF record (neutral) X-Scan-Signature: 5c335215f1b3de26d890ee84d49616ce Subject: Re: VLF: Coherent BPSK at 8270 from DF6NM Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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=0.9 required=5.0 tests=FROM_ENDS_IN_NUMS 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 Another successful test by Markus DF6NM this morning, 2014-05-18. Sending 100 bits at 8270.000 Hz using a rate 1/8 convolutional code with constraint length 25. The data rate was 24.2 bits per hour and the Shannon capacity for the channel is around 28 bits per hour. The 100 bit message was encoded into 992 BPSK symbols sent coherently at 15 seconds per symbol. The decoder corrected 343 symbol errors - a symbol error rate of 34.6% which corresponds to Eb/N0 of around -2.0dB. A one hour carrier immediately following the message enabled a signal strength measurement: 0.09 fT and S/N of 13.2 dB in 278 uHz. The calculated Eb/N0 for that is -1.57 dB which happens to be just about exactly at the Shannon limit. The decoder running on a 32 core AWS EC2 c3.8xlarge took about 3 minutes to find a reference phase and decode the signal. The message ranked at the 28th maximum likelihood path through the Viterbi trellis. This is possibly the strongest forward error correction code ever transmitted by a radio amateur. In combination with coherent signalling and Viterbi list decoding, a circa 10uW ERP signal is decoded with 95% reliability at a range of over 1000km and achieves 85% of the Shannon capacity. -- Paul Nicholson --