> I've noticed that the emphasis on this list seems to be placed on > fast measurements of short-term drift. I'm more interested in long > term drift, so I use a clock accumulator to measure drift over > months (no setup has lasted a year, yet). > > Why is the focus on short-term drift? > > Bill Hawkins
Bill, Sounds like you're doing the right thing. I think the key point is not so much short- or long-term but how long do you have to wait before you get reliable results. And this is especially true if you're testing or repairing some surplus gear from eBay. You want to know as much as possible about the performance in as short a time as possible. We could put a Cs standard in a closet with a Z3801A, TI counter, UPS, and logging PC and take one reading against GPS each day. A year later, assuming nothing went wrong, we could look at a very nice plot and make very solid statements about frequency drift rate, etc. But sometimes it's nice to see trends as soon as they are statistically accurate. And that may take much less than a year. Yet it may take longer than days or weeks. Everything is relative. Quartz drift rates can be measured in a matter of hours or days; accurate rubidium drift rate measurements take longer; maybe days to weeks. And Cesium even longer than that. What started this thread, and one similar to it almost a year ago, was Brooke's Excel plots showing anomalous frequency drift in one of his FTS 4060's. He wasn't out to measure Cs drift as far as I remember; it just showed up in his plots. /tvb _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
