From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.perfora.net (mout.perfora.net [74.208.4.194]) by huchra.bufferbloat.net (Postfix) with ESMTP id EE246202224 for ; Sat, 24 Mar 2012 07:14:10 -0700 (PDT) Received: from [192.168.83.5] (c-76-97-152-51.hsd1.ga.comcast.net [76.97.152.51]) by mrelay.perfora.net (node=mrus4) with ESMTP (Nemesis) id 0M8eIl-1SXUkl3AmZ-00vZOV; Sat, 24 Mar 2012 10:14:09 -0400 Message-ID: <4F6DD6AF.1040901@c3energy.com> Date: Sat, 24 Mar 2012 10:14:07 -0400 From: "Ron Frazier (NTP)" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100722 Eudora/3.0.4 MIME-Version: 1.0 CC: "thumbgps-devel@lists.bufferbloat.net" References: <4F6CE652.2010309@c3energy.com> <4F6D285C.1070505@c3energy.com> <4F6D3E94.4080902@c3energy.com> <4F6D6BEB.1070606@c3energy.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:g8HkiW5NlxQAIOV1a/p6t78vp7BdbCh+cQ8hdZzLmkn NbLgWbA17KhRPRRDvsauQN0NjCbcJ5CJI+kmbnINAEwz+ieUQ/ uhzLkYtBtgwjbAJry0ycuACnv3iy3C59kg0DmgQHwu5jnnLMzw amWpIqbbsEx+bFnWgCcB0N7C0/9Cr4Av/I3FOOCmejz4Nz3TnU Hal/uDw9kNaiQNJedJ+SWIEJ1qS0HT5d/dnU6ArbcCywhywZRM lWEafw6UpEI7dv9Y/Pa0Gge2ednoDK9aT44j3yzW1uq7ki4IUa pyBA65GWmBT1yeGPpIOhSn2W/7su1O9jm1khBE5eSHDqaPn477 4D61FkSO7iqtAkemV+FGsMM/GkzpNzBuFuFceLkAn Subject: Re: [Thumbgps-devel] YEA! My Sure Electronics GPS just arrived. X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 24 Mar 2012 14:14:11 -0000 Since I wrote that, it seems to have centered itself around zero. I now have a very nice + 1.2 ms / - 1.2 ms offset pattern. Since I've been struggling to get anything under 50 ms with other technology, this looks really sweet to me. http://dl.dropbox.com/u/9879631/Sure%20board%20first%20night%20pt1.jpg http://dl.dropbox.com/u/9879631/Sure%20board%20first%20night%20pt2.jpg Conversion of these images to jpeg reduced the clarity a bit, but you can still see what's happening. Sincerely, Ron On 3/24/2012 4:21 AM, Andrew McGregor wrote: > I know why it isn't centered... it's because it is taking a USB polling round trip to get the signal back. The PPS happens somewhere between two polls every 1 ms, and it takes another 1 ms to come back. > > On 24/03/2012, at 2:38 PM, Ron Frazier (NTP) wrote: > > >> I now have the PPS circuit working on the Sure board. I have not soldered it yet. I just taped a jumper wire between the PPS test point at the edge of the board and the DCD pin 1 on the RS-232 port. The serial data is coming in through the Trendnet TU-S9 serial - USB converter, which is passing DCD. I'm getting + .5 / - 1.5 ms offsets. The PPS is nowhere to be seen on the statistics screen, but it is obviously working. I don't know why it's not more centered around zero, and maybe that will change. However, my total peak to peak range of offset variance is 2 ms, and that's coming through USB. If I can maintain that level of accuracy, and it's consistent with UTC, then I'm very happy. That's plenty good for my purposes. I still may try to run it through a real serial port on another machine just for kicks. >> >> Sincerely, >> >> Ron >> >> -- (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT c3energy.com