I need help in figuring out the parameters $c_k$ and $\theta_k$ in this situation :
- I have an auto-correlation function $R_s(n) = \left\| s \right\|^2$ for all $n \in \mathbb{Z}$
- And it must hold that $R_s(n) = \left\| s \right\|^2 = \frac{1}{2 \pi} \cdot \sum_k c_k e^{- i n \theta_k}$
Obviously, there is no periodicity since $R_s(n)$ is constant for all $n$. Am I right in assuming in this case that $n = k$ and $\theta_k = 0$ ? And how do I get $c_k$ from that? I am a bit confused.
Appreciate any help! Thanks!