[time-nuts] DOCXO vs. Rubidium medium-term stability

[Hal Murray]

jabson at quasarfs.com said:
> The mobile station can be synchronized to GPS initially to synchronize its
> clock as described above but will then have to rely on a free-running
> oscillator. The stability of this oscillator will dictate how much drift the
> mobile station's clock will experience relative to the reference stations.
> Keeping this drift as low as possible is my goal. 

Don't get hung up on the "D" idea.  There are many very good single oven 
OCXOs out there.

I think you will be much happier if you figure out how low a drift you need.  
I'm guessing you don't have a firm number because it interacts with other 
parts of the system and you are still designing that part.  You need some 
rough numbers for sanity checking your options.

Typical GPSDO boxes are good for a few microseconds over 24 hours of 
holdover.  Is that within your ballpark?  You can probably do much better 
than their spec sheet if your temperature is stable.

Do you need one for a single experiment, or many for a production run?  Do 
you need to prove it is good-enough from the spec sheets or can you try one 
in the lab, and run with it if it works?

My suggestion would be to get a couple of good OCXOs, put them in the lab 
next to your Rb, and see how well they work.  It's probably worth a few phone 
calls to see if the vendors have any data on 12 hour holdover.  (But check 
the environmental conditions.)



-- 
These are my opinions, not necessarily my employer's.  I hate spam.