Multiple choice

If the power spectral density of stationary random process is a sine-squared function of frequency, the shape of its autocorrelation is

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If S_x(ω) = sin²(ω) (sine-squared), then autocorrelation R(τ) is the inverse Fourier transform. The Fourier transform of sin² produces a triangular function (convolution of two rect functions becomes triangle). The autocorrelation shape is triangular, decaying as lag increases - matches option A.