Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dk02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4BAB538000093; Sun, 6 May 2012 11:40:53 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SR3Yk-0005hh-Lg for rs_out_1@blacksheep.org; Sun, 06 May 2012 16:39:42 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SR3Yj-0005hY-VP for rsgb_lf_group@blacksheep.org; Sun, 06 May 2012 16:39:41 +0100 Received: from cpsmtpb-ews06.kpnxchange.com ([213.75.39.9]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1SR3Yi-0001Dj-5N for rsgb_lf_group@blacksheep.org; Sun, 06 May 2012 16:39:40 +0100 Received: from cpsps-ews02.kpnxchange.com ([10.94.84.169]) by cpsmtpb-ews06.kpnxchange.com with Microsoft SMTPSVC(6.0.3790.4675); Sun, 6 May 2012 17:39:39 +0200 Received: from CPSMTPM-TLF101.kpnxchange.com ([195.121.3.4]) by cpsps-ews02.kpnxchange.com with Microsoft SMTPSVC(7.5.7601.17514); Sun, 6 May 2012 17:39:39 +0200 Received: from Extensa ([195.241.183.120]) by CPSMTPM-TLF101.kpnxchange.com with Microsoft SMTPSVC(7.5.7601.17514); Sun, 6 May 2012 17:39:39 +0200 Message-ID: <431D0943B8D44D878E6FC4E18C8A20BF@Extensa> From: "PA1SDB, Peter" To: References: <4F97E9C2.9030000@iup.uni-heidelberg.de> <7B23411450514A5CB804E6D2C65A1876@JimPC> In-Reply-To: <7B23411450514A5CB804E6D2C65A1876@JimPC> Date: Sun, 6 May 2012 15:39:38 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6001.18416 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18645 X-OriginalArrivalTime: 06 May 2012 15:39:39.0118 (UTC) FILETIME=[729AB0E0:01CD2B9E] X-RcptDomain: blacksheep.org X-Spam-Score: 1.0 (+) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: OK Jim, Tnx for sharing your experiences... 73's, Peter PA1SDB ----- Original Message ----- From: "James Moritz" To: Sent: Sunday, May 06, 2012 3:14 PM Subject: Re: LF: Generating 8970 Hz carrier with Spectrum Lab ? [...] Content analysis details: (1.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [213.75.39.9 listed in list.dnswl.org] 1.0 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) X-Scan-Signature: c9d6a1e47761f7ec7375ac340bef30d0 Subject: Re: LF: Generating 8970 Hz carrier with Spectrum Lab ? Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response 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=0.1 required=5.0 tests=MISSING_OUTLOOK_NAME 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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:428447104:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1db4064fa69b85102c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none OK Jim, Tnx for sharing your experiences... 73's, Peter PA1SDB ----- Original Message ----- From: "James Moritz" To: Sent: Sunday, May 06, 2012 3:14 PM Subject: Re: LF: Generating 8970 Hz carrier with Spectrum Lab ? > Dear Andy, LF Group, > > A bit late, but never mind... > >> Has anyone tried using an external USB soundcard with a separate >> locked clock? Most work from a 12MHz crystal which can be replaces >> with a GPS locked source without too much effort. But I can't help >> wondering if there will be subsequent USB synchronisation glitches >> upsetting the input sampling. > > > I can confirm that glitches do occur with USB sound cards. I have found this > to be a perennial problem trying to use such a sound card with the laptops I > have available. For 9kHz reception, the relatively rapid temperature > fluctuations inside the laptop, and resulting cyclic drift of the internal > soundcard sampling frequency interfere with the operation of DL4YHF's > ingenious sample rate correction facility in SpecLab, making the internal > sound card unusable for FFT resolution below a few millihertz. I found my > USB soundcard solved this particular problem quite well, but introduced > glitches that made achieving FFT resolution in the uHz range impractical. > > Watching Speclab's sample rate correction "history" window, the USB card > sample rate typically starts off a few hundred ppm low (much larger than the > actual clock frequency error), but remaining stable to within a few ppm, but > then at unpredictable intervals abrupt jumps in sample rate of a similar > order of magnitude occur, with corresponding "blips" on the spectrogram > traces. The reported sample rate is always lower than the nominal value, > suggesting that some samples are being periodically discarded somehow. > > The sound card uses a single-chip integrated audio codec and USB > transceiver, using a single 12MHz crystal. I can't really believe in "USB > slippage" in the hardware - surely losing some of the data would either be > handled quietly by the USB error checking, or result in endless error > messages. The same sound card seems to work in a glitch-free way when > plugged into my desktop machine, where the reported sample rate error is in > line with the error in the crystal frequency. > > Cheers, Jim Moritz > 73 de M0BMU > > >