Passive interference simulation in radars with digital antenna arrays

Abstract

The problem of imitation modeling of passive interference is considered in the context of devel-oping algorithms for space-time processing of broadband signals in a radar system with a digital antenna array. Spectral and correlation characteristics of passive noise are discussed in the frame-work of Gaussian, polynomial (fractional rational) and exponential models. Due to the broadband nature of probing signals, the formation of the antenna array directional pattern is carried out by controlling the time delays of oscillations arriving at the array elements, which is implemented in the frequency domain through complex weighting factors. Modeling of passive interference as a sta-tionary complex random process is performed in discrete "slow" time, with each complex vector of samples being spaced from neighboring vectors by the value of the repetition period of the probing pulses. The known method for modeling passive interference based on a shaping recursive filter is unsuitable for use in the case of an interference spectrum other than rational. The method for model-ing the vector of correlated samples using the Cholesky expansion of the noise covariance matrix is inapplicable when the correlation coefficient is close to one. A method is proposed for modeling masking extended passive interference of a wide class based on filtering a sequence of complex pseudo-random vectors in the frequency domain with the use of a fast Fourier transform.