Phase modulation perturbed by amplitude modulation in RF

Dear all,

I am dealing with a physical signal where the information that I seeking of measuring is encoded in the phase

, where

by [tex]cos( 2 \pi f_m t)[\tex] on one arm and by [tex]sin( 2 \pi f_m t)[\tex] on another arm and from these signal I hope I can extract [text]\Phi(t)[\tex] without the influence of my detector.

Can someone confirm that the IQ demodulation is indeed a way to shortcut the influence of my detector? If not does someone has an idea of how I can get rid of the influence of my detector?

Best