Анализ систем обработки сигналов на фоне пассивных помех

Abstract

An adaptive quasi-optimal "band-stop filter – multichannel filter" system is analyzed. Adaptation of such system opens the possibility of taking into account the nature of noise represented by an additive mixture of correlated and uncorrelated components corresponding to clutter and the receiver’s own noise. A likelihood function establishing the dependence of the processing system input samples on the clutter correlation matrix is introduced, using which the accuracy of estimating the unknown clutter parameters, namely, the interperiod correlation coefficients and the Doppler phase shift can be analyzed. Formulas establishing a relation between the accuracy of estimating the unknown clutter parameters, the amount of training sample, and spectral correlation properties of the clutter are obtained proceeding from the Cramer-Rao bound. The calculation results were found to be in fairly close agreement with the empirical results obtained from statistical simulation of the relevant evaluation algorithms on a PC; this agreement has confirmed the asymptotic efficiency of the maximum likelihood estimates used in adapting the processing systems. The processing system efficiency analysis carried out by using the asymptotic properties of the maximum likelihood estimates establishes a relationship between the suppression of clutter in the system and the errors of adapting the weighting coefficients of the adaptive band-stop and multi-channel filters to the unknown clutter parameters. In so doing, a linear approximation of the dependencies of weighting coefficients from the interperiod correlation coefficient estimate was used under the assumption that the form of the clutter correlation function’s envelope is known. The relationships obtained from the performed analysis allow the user to select the training sample amount depending on the preset adaptation loss value, spectral correlation properties of clutter, and processing system structure.