[time-nuts] Rb vs.Crystal OCXO
Tom Van Baak
tvb at LeapSecond.com
Fri Apr 25 16:30:03 EDT 2014
> Hi Everyone,
> I'm newer to this forum but I really enjoy reading the discussions. I have
> a pretty basic question.
> I'm wondering why one would chose an Rb Oscillator over a traditional OCXO?
> It does not immediately appear there is a phase noise advantage in the Rb..
Welcome to time-nuts. Good question.
In some applications the exceptional long-term frequency accuracy and stability you get with Rb is more important than the better phase noise, smaller size, lower power, better short-term stability, longer lifetime, or cheaper price that you get with an OCXO.
When you buy a new OCXO, it might be accurate to 4 or 5 or 6 digits, out-of-the-box. You have to mechanically (screw) or electronically (EFC) calibrate it to get closer. If you want, say, 9 digits of accuracy, then you may have to re-calibrate it every day or at least once a week.
When you buy a new Rb, it might be accurate to 9 or 10 or 11 digits, out-of-the-box. If you want, say, 9 digits of accuracy, then you may have to calibrate it every couple of years.
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