Return-Path: X-Spam-DCC: paranoid 1170; 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 t9O8e81x014548 for ; Sat, 24 Oct 2015 10:40:08 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZpuJS-0002r1-9b for rs_out_1@blacksheep.org; Sat, 24 Oct 2015 09:36:30 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZpuJR-0002ql-TX for rsgb_lf_group@blacksheep.org; Sat, 24 Oct 2015 09:36:29 +0100 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZpuIS-0003WZ-2d for rsgb_lf_group@blacksheep.org; Sat, 24 Oct 2015 09:36:28 +0100 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 7BD7D3273F0 for ; Sat, 24 Oct 2015 09:27:11 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 5B59328A012C for ; Sat, 24 Oct 2015 08:35:16 +0000 (UTC) Message-ID: <562B42C4.1040403@abelian.org> Date: Sat, 24 Oct 2015 08:35:16 +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: <562ABB44.9060709@gmail.com> <8D2DC03E4BF816E-12A8-1699E1@webmail-vd008.sysops.aol.com> <562AE5E2.9000601@virginbroadband.com.au> In-Reply-To: <562AE5E2.9000601@virginbroadband.com.au> X-Scan-Signature: ac0f6ff1af52b6036ac1f4fe0c2bd52c Subject: Re: LF: Coherent BPSK on LF using EbNaut 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: 4600 Marcus wrote: > The equispaced lines are presumably from Loran-C Anthorn, > their frequencies are exact multiples of 50000 / 6731 Hz. Thanks, I was wondering about those. The tx is 155km from here. Those sidebands might turn out to be useful markers. Domenico wrote: > Initial transmission at 22.00 [CET!] will contains 22 > characters at 1 s/symbol Decoded easily: Eb/N0=7.5 ber=0.19 decode time 22 seconds Quite a strong signal, the BPSK was actually visible on the spectrogram! I got no decode of the following hourly transmission with 6 chars, 3 second symbols. I did not try any time or frequency offsets, or any impulse blanking. Seems to be quite a lot of impulse noise, appear not related to sferics. I suppose local interference, switching transients. Carrier measurement: http://abelian.org/tmp/lf151023c.gif 21dB S/N in 3.33 mHz. Spectrum peaks at 137502.241338 Hz +/- 1uHz. The 20:00 UT 22 char message doesn't decode when I use 137502.241338 for the frequency, so spectrum peak is not a good guide. Plugging 21dB and 300 seconds into the carrier measurement on the signal calculator page http://abelian.org/ebnaut/calc.php?sndb=22&snbws=&snmps=300&code=8K19&sp=1&L=1&nc=22&submit=Calculate predicts Eb/N0 = 7.48 for the 22 char 1 second symbols, which is close to the Eb/N0 = 7.5 of the actual decode. Dropping the power by 10dB and changing to 3 seconds, 6 chars, http://abelian.org/ebnaut/calc.php?sndb=12&snbws=&snmps=300&code=8K19&sp=3&L=1&nc=6&submit=Calculate gives Eb/N0 of 4.14 dB which should easily decode. So, I have some investigation to do! -- Paul Nicholson --