Digital Drive

Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it.

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RE: Possible to split a 10Mhz clock output?

Posted by AbeCollins on December 18, 2016 at 22:11:35:
Very cool! But how do you know that it's output is precisely 10.00000000 MHz as shown on the HP frequency counter?

Is the reference clock in your HP frequency counter more accurate than your Rubidium oscillator? ;-)

We used a reference Rubidium oscillator that was calibrated and traceable to the National Bureau of Standards (now called NIST). The signal from the reference Rb oscillator was input into a Tracor frequency difference meter and compared against new Rb oscillators that we produced. The reference Rb oscillator would be sent back to a calibration lab periodically to ensure that it's accuracy was certified and traceable to NIST.

It's interesting to note that the freq diff meter needle would swing in one direction and then the other as the crystal in the Rb oscillator would be swept in each direction (with an error voltage applied to a varactor diode which changes it's junction capacitance which would of course alter the frequency of a tuned circuit) until the physics package warmed up and disciplined the crystal output and locked it to the hyperfine transition state of the Rb atom.

Here's an old Tracor Frequency Difference meter similar to the one I used to use. Fun stuff back in the day. Enjoy your Rb oscillator.