Return-Path: <owner-rsgb_lf_group@blacksheep.org> 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=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=1 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 v3NEHsrx005689 for <sq5bpf@lipkowski.org>; Sun, 23 Apr 2017 16:17:55 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1d2IHS-0004lC-3h for rs_out_1@blacksheep.org; Sun, 23 Apr 2017 15:14:26 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1d2IHQ-0004l3-3e for rsgb_lf_group@blacksheep.org; Sun, 23 Apr 2017 15:14:24 +0100 Received: from emout02.email.it ([212.97.34.18]) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from <smtp01@email.it>) id 1d2IHM-0006xG-49 for rsgb_lf_group@blacksheep.org; Sun, 23 Apr 2017 15:14:22 +0100 Received: from emout02.email.it (localhost [127.0.0.1]) by emout02.email.it (Postfix) with ESMTP id 0C79B82186 for <rsgb_lf_group@blacksheep.org>; Sun, 23 Apr 2017 16:14:18 +0200 (CEST) Received: from x220.localnet (94-36-77-69.adsl-ull.clienti.tiscali.it [94.36.77.69]) by emout02.email.it (Postfix) with ESMTPA id E430282184 for <rsgb_lf_group@blacksheep.org>; Sun, 23 Apr 2017 16:14:17 +0200 (CEST) From: Claudio Pozzi <smtp01@email.it> To: rsgb_lf_group@blacksheep.org Date: Sun, 23 Apr 2017 16:14:44 +0200 Message-ID: <1581982.q1LxLSTeDg@x220> User-Agent: KMail/4.14.1 (Linux/3.16.0-4-amd64; KDE/4.14.2; x86_64; ; ) In-Reply-To: <001901d2bc1d$23d4d570$6b7e8050$@comcast.net> References: <79fa174a-23e3-4c02-5654-ffa8905d38d8@abelian.org> <2232d14e-843d-433d-d2a8-940129c67b35@abelian.org> <001901d2bc1d$23d4d570$6b7e8050$@comcast.net> MIME-Version: 1.0 X-Scan-Signature: 0317e2ac8ed27149e57223a21580246d Subject: Re: VLF: Some natural signals Content-Type: text/plain; charset="utf-8" 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 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by lipkowski.org id v3NEHsrx005689 Status: RO X-Status: X-Keywords: X-UID: 11442 On Sunday 23 April 2017 06:34:07 you wrote: > Thanks Paul, > > What a wonderful sound. > > Unfortunate that bird's magnetic sensors don‚Äôt have the > sensitivity/bandwidth for what you captured; they could perhaps tune their > nav systems for reduced sensitivity to the disturbance that chorus > indicates. > > Do you know if anyone has made audio translations of the mHz to 1Hz > ionospheric-TEC waves (which modulate signals in HF and other bands)? I'm > referring to what some folks call ULF waves, where ULF refers to a > geophysical-community convention of roughly 1 mHz to 1 Hz. > > Or if anyone has made audio translations of the mHz to Hz modulation that > magnetic storms can impress on VLF signals? > > 73, Jim AA5BW > Hi Jim. Interesting question,but how can I made this audio translation? The 10 mHz signal period (T=1/F) is 100 seconds. So if I modulate in frequency or in amplitude a 1000 Hz carrier what sound can I heard? And the sound of the translated frequency like SSB USB (1000+0,01 Hz) is indistinguishable from a 1000 Hz sound. A 10 mHz frequency signal must be at least 100 seconds long for one complete sinusoid. If it's shorter how can I measure the frequency? Can I assume that the missing part of signal is a sinusoid? In my opinion VLF signals (lower than few Hz) are better analyzed in time domain, not in frequency domain. If you listen a 3600 seconds recording of VLF sound reproduced high speed in 3,6 seconds the sound should be interesting. But each "frequency" is multiplied by 1000. The short wave AM broadcasting fading is an "amplitude modulation" with few tenths of Hz frequency (and some group delay distortion). 73 de Claudio IK2PII -- ZE-Light e ZE-Pro: servizi zimbra per caselle con dominio email.it, per tutti i dettagli Clicca qui http://posta.email.it/caselle-di-posta-z-email-it/?utm_campaignÍil_Zimbra_102014 Sponsor: Idee regalo classiche o alternative? Trova l'offerta migliore in un click Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid327&d#-4