A random process has an autocorrclation funclion
$$
R_{x x}(\tau)=\left\{\begin{array}{ll}
P[1-(2 \tau / T)] & 0<\tau \leq T / 2 \\
P[1+(2 \tau / T)] & -T / 2 \leq \tau \leq 0 \\
0 & \tau<-T / 2
\end{array} \text { and } \tau>T / 2\right.
$$
Find and sketch its power density spectrum. (Hint: Use Appendix E.) *