Return-Path: X-Spam-DCC: paranoid 1290; 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 u1IBF9Aq018447 for ; Thu, 18 Feb 2016 12:15:09 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aWMUV-00053e-Mv for rs_out_1@blacksheep.org; Thu, 18 Feb 2016 11:11:23 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aWMUV-00053U-Ej for rsgb_lf_group@blacksheep.org; Thu, 18 Feb 2016 11:11:23 +0000 Received: from brian.netcom.co.uk ([217.72.171.64]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1aWMTP-0006gA-UP for rsgb_lf_group@blacksheep.org; Thu, 18 Feb 2016 11:11:22 +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 E344E320089 for ; Thu, 18 Feb 2016 10:48:00 +0000 (GMT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 048CF28A118C for ; Thu, 18 Feb 2016 11:09:59 +0000 (UTC) Message-ID: <56C5A687.5070904@abelian.org> Date: Thu, 18 Feb 2016 11:09:59 +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: <56C3A295.1070604@gmail.com>, <8D337C07D0EF85E-638-5CB535@webmail-vd021.sysops.aol.com>, <56C4D519.27278.F13C0A@roelof.ndb.demon.nl> In-Reply-To: X-Scan-Signature: 7001055fa59a9c23b9831ea6d317a074 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: 6882 I wrote: > 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 ... I tracked this down to a problem in my receive timing system, the one that mixes the signal and PPS into a BT878. With that fixed, I can no longer reproduce the anomaly here. EbSynth checks out ok - measuring the output phase against a GPSDO reference shows a phase jitter around 0.14 degrees RMS at 53077.222222 Hz and the peak phase deviation on a run of a few hours was only 0.34 degrees. The phase plot of a BPSK transmission looks real good. So maybe there's a problem with the multiplier, which uses junk box parts and an unregulated supply. It wouldn't be too hard for the thing to introduce an intermittent phase error, eg by a fluctuating threshold of a Schmitt trigger or an unstable capacitor. -- Paul Nicholson --