On Tue, 2008-11-25 at 20:06 -0500, Richard B. Gilbert wrote: [...] > The most important thing to do or attempt is to get a primary source of > time. This can be an atomic clock (extremely expensive, extremely > stable, extremely accurate), or something directly connected to an > atomic clock. A GPS timing receiver will capture signals from four > satellites and solve a system of four equations in four unknowns: time, > latitude, longitude, and elevation. Each of the satellites carries an > atomic clock! The GPS timing receivers sell for ~$100 and up. If you > can site such a receiver so that it has an unobstructed view of the sky, > this is a very good source of time. > > If it is not possible for you to have your own stratum 1 time server, > there are a fair number of them on the internet. Stratum 2 servers are > even more plentiful. Stratum one servers have direct access to an > atomic clock or equivalent; e.g. GPS receiver. Stratum two servers get > their time from stratum 1 servers. Stratum 3 gets time from stratum 2. > . . . If you can't use internet servers and you can't set up your own > stratum one server, you are SOL. > > It is possible to "fake it" using a server that has a good clock but > performance will not be as good as having an atomic clock at the root of > the tree. That rock solid beat of one second per second is easy to get > in step with and easy to keep step with. > > An unsynchronized clock WILL drift and will be more difficult to get in > step with and keep step with. > > I can tell you from experience that a GPS receiver will give you rock > solid time and that clients will synchronize easily with it. So will an > atomic clock but that costs $50,000 or $100,000 more than the GPS receiver!
Thank you for the detailed explanation. I appreciate that. :-) ./Cal _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
