Cross-Spectrum L(f) Workshop

E. Rubiola, FEMTO-ST & C. W. Nelson, NIST

Wednesday, July 12th, 18:00 – 20:00

at The Gallery (downstairs, lecture rooms level)



Introduction and news after the 2015 workshop

E. Rubiola, FEMTO-ST & C. W. Nelson, NIST


Labs and industrials issues

A few short presentations by qualified players*, to be detailed later.


Round table





* To contribute, email to cross-spectrum @

Registration is free and would be appreciated:

To register, please send an e-mail to cross-spectrum @ with the following infos: NAME, Surname, Laboratory/Company, Country, e-mail address.

The cross spectrum method is a standard practice in the measurement of phase noise, widely used by manufacturers and customers/users of oscillators, and by academic/public labs as well, including the primary labs.
In short, the instrument has two separate channels – each consisting of a reference oscillator and a phase detector – which measure simultaneously the oscillator under test (DUT). Assuming that the two channels are statistically independent, the average cross spectrum converges to the DUT noise, rejecting the single-channel noise.
Unwanted correlated effects always exist, for fundamental reasons or as a result of uncontrolled practical issues. Correlation can be either positive or negative, which results in over or under estimation of the DUT noise. The latter case may be embarrassing.
This workshop follows two previous workshops on the same topic. The first was at the LNE, Paris, December 15, 2014. The second was in Denver, April 15, 2015, as a side event of the EFTF-IFCS Joint Meeting.
The purposes of the 2017 workshop are
• Inform the community that measurement errors and inconsistencies are around the corner.
• Summarize the state of the knowledge, and the progress since 2015.
• Encourage the participants to communicate their experiences and needs.
The workshop is also intended as an occasion for a voluntary collaboration between manufacturers of oscillators and instruments, users/customers, and Gov/Int’l labs.
Conclusions are intended to progressively provide guidelines or recommendations, and ultimately as a contribution to updated procedures and standards.