This was measured by taking a H-maser 10MHz signal (output from a frequency distribution amplifier) and splitting it in two for the 3120A REF and DUT channels with a ZFSC-2-1+ passive splitter.
The first measurement is with 50 Hz bandwidth and a duration of 5 minutes. The second measurement is at 5 Hz bandwidth and ran overnight for 12 hours.
Here's the ADEV plot with some typical performance-curves added.
- BVA8607: http://www.oscilloquartz.com/files/1363164953-Br_%20OCXO%208607.pdf
- PRS-10: http://www.thinksrs.com/products/PRS10.htm
- 53230A: http://www.anderswallin.net/wp-content/uploads/2015/04/Keysight_53230A_noise_floor.png
- 50cm optical cavity: http://arxiv.org/pdf/1502.02608v2.pdf
- Sr lattice clock: http://arxiv.org/pdf/1309.1137v2.pdf