How to address being interested in two areas in statement of purpose

I am applying to graduate school in US. I am wondering how I can write statement of purpose If I am interested in both signal processing and communication. Should I talk about why I am interested in both and talk about researches and projects I have done in both areas and my future research in both fields since I like both equally?. However I was thinking this is too much and is going to pass the word limit for statement of purpose. I am looking for some advice about this. Any advice will be greatly appreciated.