Return-Path: X-Spam-DCC: paranoid 1233; 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 t92347gE031927 for ; Fri, 2 Oct 2015 05:04:07 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZhqX7-0007Lt-Nk for rs_out_1@blacksheep.org; Fri, 02 Oct 2015 03:57:17 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZhqX7-0007Lk-6J for rsgb_lf_group@blacksheep.org; Fri, 02 Oct 2015 03:57:17 +0100 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZhqWL-00059w-Tm for rsgb_lf_group@blacksheep.org; Fri, 02 Oct 2015 03:57:16 +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 E5CA73273E8 for ; Fri, 2 Oct 2015 03:48:38 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id CA0BB28A102B for ; Fri, 2 Oct 2015 02:56:13 +0000 (UTC) Message-ID: <560DF24D.3050309@abelian.org> Date: Fri, 02 Oct 2015 02:56:13 +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: <560D660F.2070405@gmail.com> <8D2CAA79AE1077F-C0EC-1534D6@webmail-vm004.sysops.aol.com> In-Reply-To: <8D2CAA79AE1077F-C0EC-1534D6@webmail-vm004.sysops.aol.com> X-Scan-Signature: b77892ad90d0261eaf071f4f6cf31464 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: 4238 Found myself ordering a Trimble 10MHz GPSDO the other day. I have a Thunderbolt but don't want to dedicate it to a receiver because it's handy in the lab. Andy wrote: > The four-byte packet format has been selected so it is > flexible enough to allow a timestamp to be included in > the stream, and possibly some info on the block size, > with blocks suitably labelled with a header for alignment You might consider the packet format used by vlfrx-tools, which (correct me if I'm wrong Wolf) can also be read by Spectrum Lab. It has the fields you need and a magic number to sync on. Rummaging through my junk box, there's enough parts for a simple 137 kHz rx, one axis. I've a spare BT878 card which captures mono 8 bit samples at 448k/sec. If I mix PPS and a 137kHz pre-amp output, with a bit of luck that will give coherent broadband reception at LF with absolute phase. Then we can do some measurements to see how steady and repeatable signal phase can be. We might find that longer paths are better. Where's the natural noise floor at 137kHz? I guess it's around 10nV to 100nV per root Hz, depending on time of day, season? -- Paul Nicholson --