Pre-whiten approach in passive detection using small aperture array

There exists correlation between the received noises of array elements, especially when the space of array element is smaller than half-lambda. It induces fluctuant (non-white) in the spatial spectrum of noise, which deteriorates the detection performance. In this paper, two methods of pre-whiting the noise spatial spectrum are presented, which are called as magnitude normalization on noise spatial spectrum (MNNSS) and noise covariance matrix reverse (NCMR). The results of experiment show that these methods can restrain the color noise in spatial spectrum, and the detection performance is improved distinctly.