 The delay is chosen such that the passband of beamformer is directed to a specific direction in the space.This section deals with the estimation of the power spectral density of the multi-dimensional signals.The spectral density function can be defined as a multidimensional Fourier transform of the autocorrelation function of the random signal.The spectral estimates can be obtained by finding the square of the magnitude of the Fourier transform also called as Periodogram.