I sample this process with sampling frequency $f_s = 2$.
What will the frequency spectra $R_z(f)$ of the sampled process $Z$ look like? I realize that aliasing occurs since the original process contains frequencies above the Nyquist Frequency (in fact only contains frequencies above the Nyquist Frequency). The process has no frequencies within the interval where no aliasing occurs, i.e, $-1 \leq f \leq 1$. Therefore I reasoned that the frequency spectra of the sampled process would be $R_z(f) = 0, \quad 1\leq f\leq 1$ but the answer is $R_z(f) = 2, \quad 1\leq f\leq 1.$ Why?