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 uBPJ910d018055 for ; Sun, 25 Dec 2016 20:09:02 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cLE6s-0001JF-Mj for rs_out_1@blacksheep.org; Sun, 25 Dec 2016 19:05:30 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cLE6s-0001J6-AD for rsgb_lf_group@blacksheep.org; Sun, 25 Dec 2016 19:05:30 +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 1cLE6p-0002Jl-PS for rsgb_lf_group@blacksheep.org; Sun, 25 Dec 2016 19:05:29 +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=gY+L42LZvMxF2lT6xLb3CRCBL4OShXBGtGHR57d3K8I=; b=xYlqXwG+H5DKjoCuLlOJ5Lxk6A ORVQAkuxWZcB86Z2rtMqkprdfH7Aa+1eP+z3jUwSQRU1MVdqwmwgYg//7fEYZuGYrd7UXTaVpFoeD oml0zT8MAGhwz7AmRo+5a+2gCLk88IlNQF4uPq7tvg9hfXPDJUKV8yHyHn4jk4ghi1yI=; Received: from i-194-106-52-83.freedom2surf.net ([194.106.52.83]:37534 helo=pn.abelian.org) by porthos.netcom.co.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cLE6o-0003SL-1a for rsgb_lf_group@blacksheep.org; Sun, 25 Dec 2016 19:05:26 +0000 Received: from [127.0.0.1] (localhost [127.0.0.1]) by pn.abelian.org (Postfix) with ESMTP id 647B8400815 for ; Sun, 25 Dec 2016 19:05:25 +0000 (UTC) To: rsgb_lf_group@blacksheep.org References: <1593723c855-275f-1dc90@webprd-m63.mail.aol.com> From: Paul Nicholson Message-ID: <58601875.5030406@abelian.org> Date: Sun, 25 Dec 2016 19:05:25 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1593723c855-275f-1dc90@webprd-m63.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: 2e2f7cbbe9f38dd7bf3fac4fc012e6fc Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz 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: O X-Status: X-Keywords: X-UID: 9951 Some figures. Average S/N: -60.7dB in 2.5kHz after sferic blanking; Information bits: 427.5 (5.7 bits per character); Code symbols: 3872; Overall code rate: 1/9.057; Total duration: 189728 seconds; Info bit rate: 8.11 bits per hour (76% of channel capacity); With such long messages, it isn't necessary to use a CRC. The redundant 0.3 bits per character add up to 22.5 bits which is plenty enough for the outer error detection layer to use. With 22.5 plus the default 16 bit CRC, the optimum list length for the outer layer is impractical and we don't get the full coding gain. On the Linux version you can set CRC size to zero to turn it off, I'm not sure the Windows version will accept zero. -- Paul Nicholson --