Return-Path: Received: (qmail 70532 invoked from network); 15 Dec 2004 21:51:47 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore02.plus.net with SMTP; 15 Dec 2004 21:51:47 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CehOv-0008Oe-6Y for dave@picks.force9.co.uk; Wed, 15 Dec 2004 22:13:41 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CehOu-0008OZ-TW for dave@picks.force9.co.uk; Wed, 15 Dec 2004 22:13:40 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1Ceh3i-00010D-9o for dave@picks.force9.co.uk; Wed, 15 Dec 2004 21:51:46 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ceh3K-0006OK-Gz for rs_out_1@blacksheep.org; Wed, 15 Dec 2004 21:51:22 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ceh3K-0006OB-4B for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2004 21:51:22 +0000 Received: from cmsout02.mbox.net ([165.212.64.32]) by relay.thorcom.net with esmtp (Exim 4.41) id 1Ceh3C-0002h8-1S for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2004 21:51:22 +0000 Received: from cmsout02.mbox.net (cmsout02.mbox.net [165.212.64.32]) by cmsout02.mbox.net (Postfix) with ESMTP id D016A4C88B for ; Wed, 15 Dec 2004 21:51:07 +0000 (GMT) Received: from cmsapps01.cms.usa.net [165.212.11.136] by cmsout02.mbox.net via smtad (C8.MAIN.3.21K); Wed, 15 Dec 2004 21:51:07 GMT X-USANET-Source: 165.212.11.136 IN dibene@usa.net cmsapps01.cms.usa.net X-USANET-MsgId: XID644iLoVzH8429X02 Received: from [192.168.0.2] [151.41.158.179] by cmsapps01.cms.usa.net (ASMTP/dibene@usa.net) via mtad (C8.MAIN.3.21E) with ESMTP id 761iLoVzg0432M36; Wed, 15 Dec 2004 21:51:06 GMT X-USANET-Auth: 151.41.158.179 AUTH dibene@usa.net [192.168.0.2] Message-ID: <41C0B1CB.5030805@usa.net> Date: Wed, 15 Dec 2004 22:51:07 +0100 From: Alberto di Bene User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <7f.53485883.2eef867b@aol.com> <41BF1857.5020709@freenet.de> <41C088C5.7040108@freenet.de> In-Reply-To: <41C088C5.7040108@freenet.de> X-Enigmail-Version: 0.89.5.0 X-Enigmail-Supports: pgp-inline, pgp-mime Z-USANET-MsgId: XID761iLoVzH0432X36 X-SPF-Result: relay.thorcom.net: 165.212.64.32 is neither permitted nor denied by domain of usa.net X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=no, Subject: Re: LF: Coherent decoding using GPS ? Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) Wolf DL4YHF wrote: > Alberto, can you share your results with me ? I'd like to know the > jitter of the 1-pps-output, and how the unit works when there is very > limited view of the sky (which is the problem here, and also the > reason why I haven't given up the idea of building a Loran-disciplined > reference yet). Wolf, sure, as soon as I will have found the exact specs of this GPS, I will send them to you. But from a "feature sheet" about it, it is possible to read : ------ • Enhanced algorithms provide superior navigation performance in “urban canyon” and foliage environments • Adaptive threshold-based signal detection for improved reception of weak signals ------ The jitter specs, although I haven't found any number for them, judging from similar units, should not be spectacular, on the order of a few hundreds of ns. This means that in writing the software for your GPSDO you will have to filter it more heavily. I have experimentally found that a Kalman filter does wonders for this. The other side of the medal is that the error signal will react much more slowly to phase changes of the oscillator, which in turn implies that you will have to use a very good OCXO, e.g. an HP 10811 and not an Isotemp as I have done in my GPSDO project. So my advice is to get hold of a 10811 on eBay before they are all sold and disappear.... 73 Alberto I2PHD