Mixed modulation signal and noise analysis and simulation of the rubidium gas cell atomic frequency standard

General mathematical and computational models and methods are developed for the response of the physics package of the rubidium gas cell atomic frequency to an arbitrary modulated microwave signal. Based on a mixed PM/AM plus FM model of the RF signal, these methods offer analysis and simulation solutions for optical absorption signal waveforms and derivative properties in the presence of RF harmonic distortion, noise, and carrier fluctuation. They support extended rubidium physics models that reflect optical pumping effects and resonance skew. Solutions obtained automatically include the effects of cross modulation. Advanced analysis and simulation applications of the models, methods, and solutions are identified. It is expected that the techniques and solutions will generalize to other types of frequency standard.