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A collapse of the cross-spectral function in phase noise metrology
C W Nelson1, A Hati1, D A Howe1
1National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
Abstract:
Cross-spectral analysis is a mathematical tool for extracting the power spectral density of a correlated signal from two time series in the presence of uncorrelated interfering signals. We demonstrate and explain a set of amplitude and phase conditions where the detection of the desired signal using cross-spectral analysis fails partially or entirely in the presence of a second uncorrelated signal. Not understanding when and how this effect occurs can lead to dramatic under-reporting of the desired signal. Theoretical, simulated and experimental demonstrations of this effect as well as mitigating methods are presented.
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