SYNTHESIS OF OPTIMAL ALGORITHMS OF POLARIZATION SELECTION OF USEFUL SIGNALS ON THE BACKGROUND OF PASSIVE INTERFERENCE IN SYNTHETIC APERTURE RADARS

Using the method of maximum likelihood, the optimal algorithm of polarization selection of objects on the background of the underlying surface, hydrometeors, urban buildings from aerospace carriers of radio electronic equipment has been synthesized. To solve the problem polarimetric properties of the scattered electromagnetic radiation of different natural environments and anthropogenic objects were analyzed. Has been determined the functional-determined mathematical model of the useful signal, the structure and correlation characteristics of scattered background radiation and white noise inside the multichannel receiver. It is assumed that the wanted signals are measured with phase accuracy in a coherent receiver. When solving the optimization problem, the method of the maximum likelihood functional and the likelihood functional for correlated processes were used, contains the inverse matrix of inverse correlation functions of the observation equation. The obtained signal processing algorithm, in addition to the classical operations of accumulating the trajectory signal with the preservation of the phase structure and its matched filtering, provides for polarization and frequency selection in the line of decorrelation filters. In the case when the internal noise is very small in comparison with external interference and the correlation between the channels of vertical and horizontal polarization approaches unity, almost complete compensation of passive interference occurs. Further spectral rejection of the reflected signals is practically unnecessary and it is possible to restrict ourselves only to matched filtering of the useful signal. In the absence of background radiation correlation, the channels for receiving oscillations of different polarizations become independent and the main operation for the selection of useful signals is spectral rejection of passive interference and matched filtering of the useful signal. The developed algorithm can be implement in cognitive radars due to its adaptability to the parameters of background radiation in accordance with the change in the scattering covariance matrix of the underlying surface. Based on the results obtained, a block diagram of a multichannel polarization radar with synthesized antenna aperture has been developed.