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 autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: INFN-TO: mailn 1233; 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 v5RFRbGf013887 for ; Tue, 27 Jun 2017 17:27:38 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dPsHG-0007jK-16 for rs_out_1@blacksheep.org; Tue, 27 Jun 2017 16:19:42 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dPsHE-0007jA-SH for rsgb_lf_group@blacksheep.org; Tue, 27 Jun 2017 16:19:40 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dPsHC-0005Cf-5T for rsgb_lf_group@blacksheep.org; Tue, 27 Jun 2017 16:19:39 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id D4DF1209D0 for ; Tue, 27 Jun 2017 17:19:36 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3wxqN82Dy1z10HZ for ; Tue, 27 Jun 2017 17:19:36 +0200 (CEST) Message-ID: <59527787.1000203@posteo.de> Date: Tue, 27 Jun 2017 17:19:35 +0200 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: <15ca21dc75e-1e15-bcda@webprd-m105.mail.aol.com> <0f9558b4-457d-a395-58c9-7f9be3393cdd@sky.com> <4767d79f-2bf6-d838-bfd4-3e78102d6f5d@abelian.org> <510c15eb-b57a-0ebb-9037-1f83e0652cf2@sky.com> <594933CC.70603@posteo.de> <594D2E83.7090204@posteo.de> <512e0960-4f30-7305-58d7-4d3dacb469fe@abelian.org> <594D83B1.1070702@posteo.de> In-Reply-To: <594D83B1.1070702@posteo.de> X-Scan-Signature: 086f3faad0220c9ae57a7913e711a86d Subject: Re: LF: Octo-soundcard for the Raspi, EMC 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: RO X-Status: X-Keywords: X-UID: 12129 The octo-soundcard seems to cause QRM in the GHZ range during operation: I had successful GPS reception after booting the Raspi. As soon as i initialized the soundcard, the blue PPS LED remained dark! Tried to identify the mechanism: I monitored the supply voltage, found nothing suspicious. Added common mode chokes on the coax leading the PPS signal, even disconnected that cable to break any eventual ground loops, but still no GPS reception. In a next step i removed the DC/DC converter which was mounted quite close to the GPS antenna on my plate. Still lost GPS reception during an active soundcard. Added 470 uH in series and 1 uF in parallel to the supply voltage. Still the same problem. Applied a grounded shield (against E fields) between Raspi+soundcard, still the same problem. Disconnected the RXD TXD cables of the serial interface, still the same. Used a separate supply voltage (9V block + 78L05) to power the GPS module. So there was conducting connection any more between the GPS module/antenna which is located in 6 cm distance to the Raspi (it has never been a problem in the past). => Still the GPS reception was lost when activating the soundcard! Even WLAN access is lost when running the soundcard. First i thought it is due to the real time priority of vlfrx tools. But now i have some doubts... When placing the GPS module about 6 cm more distant to the soundcard, GPS reception is restored! So now i have to apply a better shield against E and H fields coming from the board. 73, Stefan