OXCO precision clock

[Paul Elliott]

Originally Posted by Jammer

More money but a better fit for onboard use.

I love high-precision timing sources. I used to design and use gear for telecom network synchronization, dealt with nanoseconds and picoseconds on a daily basis, and have patents on my wall for precision digital timing synthesis. I have numerous OCXO's and a couple of rubidium reference oscillators in my garage lab, and am building a GPS-disciplined 10 MHz reference clock (I'm retired, it's just a hobby now.)

But I fail to see where you need 250 milliseconds per year timing accuracy on a boat, even in the apocalyptic case where we lose GPS, WWV, cellular networks, etc, and revert back to the 19th Century level of technology. If you can hold to a few seconds (or minutes!) while you are at sea, that's perfectly good for finding your way to a known piece of land. Once you are on land, you can take your known lat/lon (since you will still have charts) and taking sextant sights you can figure out what time it *really* is and thereby re-calibrate your clock.

Or am I missing something? Why do you want such a stable clock? If the answer is "just because I want it", then I certainly understand. I use that rationale quite often myself. If it's more pragmatic then I would really be interested in the reason.

[Jammer]

It's not like ordering a pizza where you can get whatever you want. That vendor has a 20 sec/month product -- no better than a $20 watch -- and the highly accurate product that is supposed to run within 250 ms per year. Take your pick.


At the end of the mechanical marine chronometer era, +or- 60 seconds a year was considered good, as a point of reference. It is said that if you're really good at shooting lunars, you can get within 60 seconds.

With a trend toward discontinuance of shortwave broadcast services -- time among them -- I was pondering alternatives. Maybe a $20 watch is good enough.