On Tue, 30 Apr 2013 13:49:43 -0400 "Tim Bastian"<n7...@yahoo.com> wrote:
> I'm a time nut newbie. My obsession started with the search for an accurate > chronometer to carry on my boat for celestial navigation. Yes there still are > a few of us left that practice the art. > > My current project is a quartz chronometer using a DS32Khz tcxo oscillator > and two 74HC4060s (+ or- 10 seconds / year). > > For my next project I'm looking at an Abricon Part Number AOCJY2-10.000MHZ > ocxo 5 ppb running through a pic and using the algorithm posted on > http://www.romanblack.com/one_sec.htm. I'm shooting for + or - 1 seconds / > year. > > Is there an archive of old posts that might be helpful in answering some of > my questions and for getting ideas. You want to read Vig's Quartz Crystal Tutorial. That explains a lot about where the instabilities of a crystal oscillator come from. You can find them (and a lot more) on http://www.ko4bb.com/ in the Manuals section. Have a look at different versions, as some interesting things were left out in the newer versions. An idea how to get to the stability you want without wasting too much power might be an MCXO. [1] gives a pretty decent overview of the way how they work including a schematic for an oscillator. [2] has some ideas how to simplify the circuit and get lower power. In your case, i guess it would be an idea to leave out the second stage frequency generation (the VCO or DDS) and generate a PPS directly from the microcontroller. Attila Kinali [1] "A microcomputer compensated crystal oscillator using a dual-mode resonator", by Benjaminson and Stallings, 1989 [2] "An Improved Method of MCXO", by Zhou, Liu, Wang, 2000 -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.