# Stationary processes and their power

The top answer to this question: Power spectral density vs Energy spectral density states:

However if random process is stationary, then it is for sure that it has some finite power over some band of frequencies

Why is that? Also, is stationarity a necessary condition for a process to have finite power over a band of frequencies?

• The highlighted statement above is false. Read this answer. – Dilip Sarwate Oct 28 '13 at 2:01