But the two are the same thing. You took the fourier transform of white noise and find white noise, both real (amplitude noise) as complex (phase noise).
You can think of it like this: the noise is not about the phase changing, it is about your ability to tell what the phase is. The noisier the signal gets, the harder time you will have to tell what the amplitude is, as well as what the phase is.
You can think of it like this: the noise is not about the phase changing, it is about your ability to tell what the phase is. The noisier the signal gets, the harder time you will have to tell what the amplitude is, as well as what the phase is.