Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w1HCsjUb029996 for ; Sat, 17 Feb 2018 13:54:46 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1en1ti-0003CL-Ju for rs_out_1@blacksheep.org; Sat, 17 Feb 2018 12:47:22 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1en1tb-0003CC-Rk for rsgb_lf_group@blacksheep.org; Sat, 17 Feb 2018 12:47:15 +0000 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1en1tY-0007K5-Ew for rsgb_lf_group@blacksheep.org; Sat, 17 Feb 2018 12:47:14 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id B0E8E20F45 for ; Sat, 17 Feb 2018 13:47:08 +0100 (CET) X-DKIM-Result: Domain=posteo.de Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1518871629; bh=IHXKyj7JVb1PLaG3nKZEMV99t21P5tBMdu32ubu5w6E=; h=Date:From:To:Subject:From; b=rfWZKqYWvtTb+YkJ5clY/67oBwZ2Xzw8gV3MwdGPMb73hWI/iTolZw7zoYinIeLbg WJi5aB0t3DhVSrMk/4IrVP8MPjQLstGtcrrPfca0OWnNUi5jDqUhmn2uQkRpJdIetB o7e4t/xsXdtlL0FWk+U8i+ai+DCCQxsQcTafbMFOqOMAoXEVqGRdDofHuyecF5awQ2 loBkHxCZeklyaytMTZZ5IFe9pwTp+xdm9WHw1hSlvhHjFCnlbOgyNRQ1H8ldLomIik UnM7lA4cAKncqAo5FpQcevN+0i3YphZy02LESFTdsyeYO2+10sreAT+9UjFaoshKpM z7QNMm1xb3XWw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3zk8sm1pPBz9rxG for ; Sat, 17 Feb 2018 13:47:08 +0100 (CET) Message-ID: <5A88244B.1020304@posteo.de> Date: Sat, 17 Feb 2018 13:47:07 +0100 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <52dea779-7aae-aff8-1072-ad24cdcd007c@freenet.de> <4024a3ab-eb61-7801-e9ad-5715c5f49546@abelian.org> <9a7cf91a-5643-9149-28a7-ce6d282db3e9@abelian.org> <1555f07a-f2a3-fb55-c246-f52442a1a723@freenet.de> <4ac6d43f-85c7-bd05-85b9-5b64ebcfbf35@abelian.org> <2f6a408a-af27-9c9b-b116-7becd9b1c66f@abelian.org> <6eced61e-a7ce-2935-195d-4a76f375b11e@freenet.de> <633c1982-97fe-7d9d-7f69-07e3503147bb@abelian.org> In-Reply-To: <633c1982-97fe-7d9d-7f69-07e3503147bb@abelian.org> X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: ...so it could be an EMC issue. One of the first things i've done is removing the ribbon cable and the audio jacks and use RG174 instead. To prevent a galvanic ground loop maybe it is worth to try to use a few turns RG174 through a ferrite core? It is quickly done... [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: d7fcd9b75df8d1b09ddef9df028bd9ae Subject: Re: LF: Testing Audioinjector Octo with RPi3 Content-Type: text/plain; charset=UTF-8; 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=0.0 required=5.0 tests=none 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 ...so it could be an EMC issue. One of the first things i've done is removing the ribbon cable and the audio jacks and use RG174 instead. To prevent a galvanic ground loop maybe it is worth to try to use a few turns RG174 through a ferrite core? It is quickly done... 73, Stefan Am 17.02.2018 12:31, schrieb Paul Nicholson: > > I had a bit of time to play again with the Octo, to investigate > where the excess timing jitter comes from. > > The stereo audio injector is giving around 20nS jitter on the > PPS from the neo-m8t. > > With the stereo card replaced by the Octo, all else the same, > the jitter varies between 300nS and over 1uS. > > A close look at the shaped PPS seen through the Octo shows some > distortion or interference > > http://abelian.org/vlf/tmp/180217a.gif > > Not sure if these are additive or little step changes in gain. > > Here's worse example > > http://abelian.org/vlf/tmp/180217b.gif > > Always the interference is on the rising and/or falling slopes > about half way. > > Not present on the PPS when viewed on a scope at the Octo inputs. > > Similar artifacts are visible on a plain old sine wave fed into > an Octo input. > > http://abelian.org/vlf/tmp/180217c.gif > > For some reason on the sine wave the artifacts are always near > the turning points. > > Meanwhile I monitored the 49.152 MHz master oscillator on a > SSB receiver and it was giving a nice pure note with no obvious > frequency or phase jitter. > > So it looks like the timing jitter on the Octo is due to its > analog inputs, not the A/D conversion timing. > > Strangely though, there's no sign of these artifacts when there's > no input to the channel. It isn't just background interference. > > I think the next step might be to bypass the Octo's input board > and take the PPS straight to the pins of the ribbon connector. > > Wondering if anyone else sees this behaviour on a PPS or sine wave. > -- > Paul Nicholson > -- >