Power spectrum randomly modulated oscillator

The power spectrum of a randomly modulated harmonic oscillator... 

Having found a relationship between the absorption lineshape associated with a periodically modulated system variable and the power spectrum of this variable, we now consider a specific example. Consider a harmonic oscillator which is randomly perturbed so that its frequency changes in time as ... 

Once we evaluate (t) we can obtain the power spectrum of the randomly modulated harmonic oscillator using the Wiener-Khintchine theorem (7.76)... 

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