Return-Path: X-Spam-DCC: paranoid 104; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,RATWARE_GECKO_BUILD autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id tB2MpJFd005350 for ; Wed, 2 Dec 2015 23:51:19 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1a4GC0-0003dg-0u for rs_out_1@blacksheep.org; Wed, 02 Dec 2015 22:48:08 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1a4GBz-0003dX-Ov for rsgb_lf_group@blacksheep.org; Wed, 02 Dec 2015 22:48:07 +0000 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1a4GAq-0000kQ-K8 for rsgb_lf_group@blacksheep.org; Wed, 02 Dec 2015 22:48:06 +0000 Received: from sb.abelian.org (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by parrot.netcom.co.uk (Postfix) with ESMTP id ED4A63273A5 for ; Wed, 2 Dec 2015 22:37:42 +0000 (GMT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 4167C28A0134 for ; Wed, 2 Dec 2015 22:46:41 +0000 (UTC) Message-ID: <565F74D0.5070801@abelian.org> Date: Wed, 02 Dec 2015 22:46:40 +0000 From: Paul Nicholson User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <8D2FA5F73070DF3-164C-1B0DC6@webmail-vm091.sysops.aol.com> <8D2FB0E41DBD77B-1DC0-A28C5@webmail-vd012.sysops.aol.com> <565F09BB.6090709@abelian.org> <565F692A.4080401@abelian.org> In-Reply-To: X-Scan-Signature: c0336009bd9bab526ca27d297ea7579a Subject: Re: LF: More EbNaut 137.777 - Dec. 1/2 Content-Type: text/plain; charset=ISO-8859-1; 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 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 5509 I ran last night's signal through vtmatch. First I retrieve 14 hours of signal and mix down to baseband I/Q at 100 samples/sec. vtread -T2015-12-01_19:00,2015-12-02_09:00 /raw | vtmult -f 2777 | # 137.777 kHz is at 2777 Hz in /raw vtresample -r 100 > v9.vt The file v9.vt is two channels, ch1 = I, ch2 = Q. Then I create a template for matching, using the known message, echo VO1NA | ebnaut -e -r100 -S2 -p8K19A -N5 | awk '{print $1}' > ref9.txt ref9.txt is just a single column of sample values, 1024 seconds long. Then vtmatch -t ref9.txt v9.vt | vtplot -gs 2000,480 produces http://abelian.org/vlf/tmp/151202a.gif in which I is the top channel and Q is below and the time axis is seconds from 2015-12-01 19:00. Each spike is a VO1NA message at half-hour intervals. Some spikes are +I, others -Q, and some are a mix. That means the phase isn't being preserved from one message to the next. The little spike in both channels at offset 3600 seconds is the 20:00 message which gave Eb/N0 = 3.4 dB. Messages that decode below about 1 or 2dB are not really visible on the cross-correlation. They might be if I knew the phase and rotated I/Q to put the signal all into one channel. I'll upload a new vtmatch.c just as soon as I've persuaded it to pass its regression tests. -- Paul Nicholson --