I am trying to generate a power spectrum by modeling like the figure: 
I would like to generate a simple cosine wave: $\cos(2\pi t)$, using a signal generator. However, I could not find a phase shift. I even looked upon the MATLAB Document, but it seemed that the generator cannot produce a cosine wave as it only has amplitude and frequency settings. However, I am required to use the generator for modeling. So What I want to ask is "Is it possible to produce a cosine wave with signal generator only?"