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,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=3 Fuz1=3 Fuz2=3 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 v69ITFo9004161 for ; Sun, 9 Jul 2017 20:29:17 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dUGt4-0008DW-9K for rs_out_1@blacksheep.org; Sun, 09 Jul 2017 19:24:54 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dUGt3-0008DN-E5 for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 19:24:53 +0100 Received: from porthos.netcom.co.uk ([217.72.171.73]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dUGsz-0001Nx-Rp for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 19:24:52 +0100 X-DKIM-Result: Domain=abelian.org Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=abelian.org ; s=default; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:To:Subject:Sender:Reply-To:Cc: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=studIDiQ5efUiWiLbxDMLMZhseUqKf8fL3e8UpZwaGc=; b=oWRR1dK1hLlDoMT+PFwulMZQLq YPYiXIRmyfXn5S+x1i+akBWUeKMKKHEbjpiwIarkZu8SGMzrPROuw6EDv55a4WsuDCxmohFViknMF H/2B50ejXvdICn4opbfEnXL8B50P3+3DmZ+nvillhBVGSQa+v5AcflWlZkCG1P7GbqbY=; Received: from i-194-106-52-83.freedom2surf.net ([194.106.52.83]:41591 helo=pn.abelian.org) by porthos.netcom.co.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dUGsz-0002AL-CL for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 19:24:49 +0100 Received: from [127.0.0.1] (localhost [127.0.0.1]) by pn.abelian.org (Postfix) with ESMTP id CB3F8400922 for ; Sun, 9 Jul 2017 18:24:48 +0000 (UTC) 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> <59626BE9.5060709@posteo.de> From: Paul Nicholson Message-ID: <65f24c4f-33f6-2925-15b9-0e5bb33efb87@abelian.org> Date: Sun, 9 Jul 2017 18:24:48 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <59626BE9.5060709@posteo.de> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - porthos.netcom.co.uk X-AntiAbuse: Original Domain - blacksheep.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - abelian.org X-Get-Message-Sender-Via: porthos.netcom.co.uk: authenticated_id: catchall@abelian.org X-Authenticated-Sender: porthos.netcom.co.uk: catchall@abelian.org X-Scan-Signature: c0e6e8bcdc231effb9da2003d606d9a2 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: 12209 Stefan wrote: > www.iup.uni-heidelberg.de/schaefer_vlf/VLF/test.vt Some good events on ch5 there, eg vtcat -S4 -E4 test.vt:1,2,3,4,5,6 | vtsgram -p100 | display http://abelian.org/vlf/tmp/170709a.gif Now to measure the noise floor. We can use vtstat -a option for this. It takes a time resolution parameter in seconds. vtcat -S4 -E4 test.vt:5 | vtstat -a r=0.01 > temp.1 temp.1 has 5 columns, col1 is the timestamp col3 is the mean amplitude (the 'DC' level) col4 is the mean squared amplitude col5 is the mean cubed amplitude Using gnuplot commands set terminal x11 set style data lines set grid plot 'temp.1' using 4 gives http://abelian.org/vlf/tmp/170709b.gif where the x axis the the number of 0.01 second samples. Using the mouse cursor in the gnuplot window you can read off the mean square amplitudes. Looks like it's normally about 1.16e-6 give or take a bit, drops to about 3.7e-7 during the dropouts. Your Octo, averaged over the 30 second test.vt using vtcat -S5 test.vt:1,2,3,4,5,6 | vtstat -a r=25 (I skip the first 5 secs because of a start-up transient) ch1: 2.4e-6 ch2: 3.3e-6 ch3: 4.2e-6 ch4: 1.4e-6 ch5: 9.1e-7 ch6: 1.8e-6 The low average on ch5 might be because it is dropping out a lot! The corresponding amplitudes from my Octo are: ch1: 3.9e-6 ch2: 5.5e-6 ch3: 3.5e-6 ch4: 2.1e-6 ch5: 3.3e-6 ch6: 3.1e-6 Conclusion: away from the dropouts, the noise floor is comparable with my Octo. Noise dropouts are 3.7e-7/1.16e-6 so about -5dB. But the signal not affected, or slightly increases! -- Paul Nicholson --