Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,RATWARE_GECKO_BUILD autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u1FNdTNZ010399 for ; Tue, 16 Feb 2016 00:39:29 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aVScs-0007Pa-G3 for rs_out_1@blacksheep.org; Mon, 15 Feb 2016 23:32:18 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aVScs-0007PM-1F for rsgb_lf_group@blacksheep.org; Mon, 15 Feb 2016 23:32:18 +0000 Received: from brian.netcom.co.uk ([217.72.171.64]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1aVSbn-0001zM-2Y for rsgb_lf_group@blacksheep.org; Mon, 15 Feb 2016 23:32:16 +0000 Received: from sb.abelian.org (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by brian.netcom.co.uk (Postfix) with ESMTP id 74BCF320085 for ; Mon, 15 Feb 2016 23:09:02 +0000 (GMT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 404FB28A0FDB for ; Mon, 15 Feb 2016 23:30:54 +0000 (UTC) Message-ID: <56C25FAE.1060409@abelian.org> Date: Mon, 15 Feb 2016 23:30:54 +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: <8D3359D28E7458C-12F0-664E0A@webmail-vm183.sysops.aol.com> <8D336061255ACC5-1ECC-632152@webmail-vd008.sysops.aol.com> In-Reply-To: X-Scan-Signature: 046f068074e745d5c60ca47deee9b503 Subject: Re: LF: EbNaut on MF Content-Type: text/plain; charset=ISO-8859-1; 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 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 6836 I wrote: > all the symbol error rates are higher than expected > for the measured carrier S/N, a loss of 2 or 3dB. I can reproduce this using EbSynth and a weak near-field 9th harmonic signal. 2 to 3dB loss every time on a similar strength signal to last night's test. There is also an error floor showing up, about 6 to 8% BER with a very strong signal that should have negligible chance of even a single bit error. Something is wrong with EbSynth. The symbol errors are bunched, http://abelian.org/tmp/160215b.gif and if I repeat the test, the bunches are differently placed. It looks like the phase of the signal is deviating sufficiently to cause bit errors on a timescale of several seconds (the duration of an error bunch). It needs a 10 degree phase error to produce a bit error on a strong signal (using 9th harmonic). EbSynth then is not working as well as I'd thought with the 9th harmonic. This will badly affect the decode probability on signals near the limit. I expect it can be fixed, perhaps I'd better not take apart the MF tx just yet so we can do another test. Meanwhile - good luck Jim. If the EbNaut doesn't decode, the intervening spells of carrier are a good diagnostic. Hope that VLF ticket comes through soon - before the season is over. -- Paul Nicholson --