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: 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+deb8u2) with ESMTP id v69HoH6g004003 for ; Sun, 9 Jul 2017 19:50:18 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dUGHs-0007yS-Rp for rs_out_1@blacksheep.org; Sun, 09 Jul 2017 18:46:28 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dUGHs-0007yJ-J6 for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 18:46:28 +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 1dUGHo-0001DV-Jd for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 18:46:27 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id DD0A520C7D for ; Sun, 9 Jul 2017 19:46:17 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3x5G3s2KxZz104d for ; Sun, 9 Jul 2017 19:46:17 +0200 (CEST) Message-ID: <59626BE9.5060709@posteo.de> Date: Sun, 09 Jul 2017 19:46:17 +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> <933fcc32-d4c9-10cd-14b4-c179d66e27f9@abelian.org> <7ab80e0f-40d7-6b07-19c1-f4b256d47c52@sky.com> <594DB217.8060707@posteo.de> <2eb826d6-d299-7b37-cf64-f5bef6718f24@abelian.org> <595E4420.7060405@posteo.de> <595FB81A.5090606@posteo.de> <45775d6c-f091-37c0-0907-f01688c69b03@abelian.org> <5960BAC0.7000403@posteo.de> <5960D0B2.7030801@posteo.de> <6c1f8a0c-0dd6-ed42-cfe6-4a142e7bd3cd@abelian.org> <6991700d-fd34-7676-a182-507ea0fdae8e@abelian.org> <596208E4.5060803@posteo.de> In-Reply-To: <596208E4.5060803@posteo.de> X-Scan-Signature: f62c7cf8eeb8e5a327b71719e9bffff1 Subject: Re: LF: Octo-soundcard for the Raspi, another question 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: 12208 Hi Paul, Markus, OK, here are the results from additional tests. I took a record from CH1 and CH2 again, this time corrected by vttime which is getting PPS from CH3. http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/2970.png I concentrated on CH1 this time. The top of the spectrogram shows CH1 at 1 pixel/FFT bin the bottom shows CH1 from 0...12 kHz (24 kHz sample rate). The noise background spectrum is quite clean i find! No 1 kHz multiples having 20 dB SNR ore more, like many other soundcards have. This time i choose 2.97 kHz :-) While changing the amplitude, i disconnected the inputs, so it becomes clear when i did it. You can see harmonics from the carrier, which is due to the VFO, not due to the soundcard (something is wrong with the IC that produces the sine output on the DDS board, it has an unwanted DC component, so there are likely some nonlinearities) The signals levels were (relative to full scale): -82 dB, -52 dB, -38 dB, -32 dB and -24 dB. The AM sidebands are always at ~ -60 dBc. BUT now, the interesting part is the last one! I took cooling spray and sprayed onto different regions of the board. It seems to have an effect. The AM sidebands are gone, there are FM sidebands however. Maybe i need to use a cleaner signal source in the next tests. A picture of the board, with some modifications ( :-) ): http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/board.jpg Enough for today here... 73, Stefan