Phase noise coherence of two continuous wave radio frequency signals of different frequency

• Published in: IET science, measurement & technology measurement & technology, 2017-01, Vol.11 (1), p.77-85
• Main Authors: Rönnow, Daniel, Amin, Shoaib, Alizadeh, Mahmoud, Zenteno, Efrain
• Format: Article
• Language: English
• Subjects: Auxiliary functions; Coherence; Continuous Wave; continuous wave radiofrequency signal; Correlated parts; correlated phase noise spectra; Correlation; correlation methods; electric noise measurement; frequency 10 Hz to 1 kHz; Intelligent industri; Intelligent Industry; Linear combinations; Mathematical models; mixing product; multiplicative factor; Multiplicative factors; Noise; nonphase‐coherent generator; Offset frequencies; Offsets; Phase coherent; phase measurement; Phase noise; phase noise coherence; Phase noise spectrum; phase‐coherent generator; PNS; Radio frequencies; signal generator; Signal generators; spectral analysers; spectrum analyser; Spectrum analyzers; uncorrelated phase noise spectra
• ISSN: 1751-8822; 1751-8830; 1751-8830
• DOI: 10.1049/iet-smt.2016.0203

A method is proposed for determining the correlated and uncorrelated parts of phase noise spectra (PNS) of two continuous wave radio signals of different frequencies, ω1 and ω2. The PNS of the two signals and of mixed signals are measured. The PNS are modelled as having a correlated part that is the same for both signals, except for a multiplicative factor, and uncorrelated parts, that are different for the two signals. A property of the model that the PNS of some mixing products are linear combinations of the PNS of the signals at ω1, ω2, and ω1 − ω2 is experimentally verified. The difference of the PNS at ω1 + ω2 and ω1 − ω2 is proportional to the correlated part of the PNS and is a part of auxiliary functions that are used for finding the multiplicative factor and the correlated, partly correlated, and uncorrelated phase noise at different offset frequencies. A conventional spectrum analyser was used to characterise two signal generators, a phase-coherent and a non-phase-coherent one. For the phase-coherent generator the phase noise of two signals was found to be correlated for offset frequencies below 10 Hz, partly correlated for 10 Hz–1 kHz and uncorrelated above 1 kHz.