Return-Path: Received: (qmail 17551 invoked from network); 16 Feb 2004 09:20:12 -0000 Received: from unknown (HELO ptb-mxscan01.plus.net) (212.159.14.235) by ptb-mailstore01.plus.net with SMTP; 16 Feb 2004 09:20:12 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 47384 invoked from network); 16 Feb 2004 09:22:20 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Priority: 3 X-MSMail-Priority: Normal X-Spam-detection-level: 11 Received: from ptb-mxcore01.plus.net (212.159.14.215) by ptb-mxscan01.plus.net with SMTP; 16 Feb 2004 09:22:19 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1AsexH-000C9i-4I for dave@picks.force9.co.uk; Mon, 16 Feb 2004 09:22:19 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Asew3-00082d-7t for rs_out@blacksheep.org; Mon, 16 Feb 2004 09:21:03 +0000 Received: from [192.5.29.49] (helo=relay.dstl.gov.uk) by post.thorcom.com with smtp (Exim 4.14) id 1Asew2-00082U-GO for rsgb_lf_group@blacksheep.org; Mon, 16 Feb 2004 09:21:02 +0000 Received: (qmail 25272 invoked from network); 16 Feb 2004 09:20:59 +0000 X-Fake-Domain: unknown Received: from unknown (HELO warlock.dstl.gov.uk) (192.5.29.10) by relay.dera.gov.uk with SMTP; 16 Feb 2004 09:20:58 +0000 Message-ID: <7D653C9C42F5D411A27C00508BF8803D01A9F423@mail.dstl.gov.uk> From: "Talbot Andrew" To: rsgb_lf_group@blacksheep.org Date: Mon, 16 Feb 2004 09:20:58 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Subject: RE: LF: Timing GPS and Spam Content-Type: text/plain; charset=iso-8859-1; format=flowed X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 1) Since transferring this reflector to my works computer and cancelling the old home EMail address most spam has stopped. However, I now get the occasional one to work which gets through the firewall. Obviously the LF reflector has something to do with this, but at least one per fortnight is better than 40 per day ! 2) I have done some further tests on the Jupiter T GPS module with its 10kHz output. Phase locking this to a 5MHz reference suggests a really good (for LF to HF use anyway) GPS Discpiplined oscillator is trivially simple - it doesn't need a high spec ovenned oscillator and provided it is used with a bit of common sense, doesn't even need to use a controller to read the data coming out. Just a small voltage controlled TCXO, two 74HC390 chips to divide this down to 10kHz, an EX-OR gate as a phase detector and a handful or Rs and C. Once the GPS Rx has locked up, the PLL takes a further couple of minutes to lock and its all going. A good quality source, with a short term stability of fractions of a Hz over seconds and perfect in the long term. I will write this up soon - the Jupiter-T GPS module is not cheap compared with some of those around - but the ease with which it can be used as a good frequency standard... Andy G4JNT "This e-mail is intended for the recipient only. If you are not the intended recipient you must not use, disclose, distribute, copy, print, or rely upon this e-mail. If an addressing or transmission error has misdirected this e-mail, please notify the author by replying to this e-mail." "Recipients should note that all e-mail traffic on MOD systems is subject to monitoring and auditing."