[time-nuts] fleabay cesium
hmurray at megapathdsl.net
Sun May 10 00:11:22 UTC 2009
> I have a few GPSDO's (Trimble T-Bolt, Z3801A, TrueTime & HB units).
> How much better can the Cesium be than any of those ??
Here is another viewpoint... (I don't own a Cesium (but I'm looking) so my
opinions may not be relevant.)
What are you after? What is important to you?
Under the covers, a "Cesium" is just a CesiumDO with the PLL parameters tuned
to take advantage of what the Cesium tube can deliver. The basic time
constant is sub-second vs many-seconds for a GPSDO.
If you are nutty enough, the GPSDO numbers don't really match what a Cesium
can deliver in the medium term time scale, say 1000-10000 seconds. I'm
pretty sure I've seen graphs of GPS time shifting slightly from night to day
due to atmospheric changes. A Cesium won't do that.
On the other hand, a GPSDO won't have any long term drift. It's locked to
the best time we can get. If you wait long enough a Cesium will drift. Not
very fast, but it will drift.
These are my opinions, not necessarily my employer's. I hate spam.
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