I am enrolled in Civil Engineering. I need to understand stochastic processes for completion of my project. I have just completed first 9 chapters from the book "Probability, random variables and stochastic processes" authored by Papoulis.
Basically, I understand random processes and distribution theory as an engineer (no rigorous proofs). My next task is to understand spectral representation theorem. However, it is pretty difficult to study from Papoulis; probably because I don't have a background in Electrical Engineering. For example, chapter 11 (which is on spectral representation) starts from minimum phase systems. I have no idea what that is. Also, most of the online resources do not start from basics.
I need few references to good material on spectral representation theorem so that I have at least a working knowledge of it. Any help is appreciated.