Model-Parametrical Spatial Signals Processing Use in Radar with Mechanical Scanning Antenna

摘要

The fleet of modern radar systems contains a large quantity of radars with mechanic space scanning over angular coordinates. Modernization of such radars with the aim to improve accuracy and resolution over the angle with small hardware-software costs is an issue of the day. In those cases when direction of arrival estimation and resolution of sources is performed at the expense of mechanic scanning of radar system (RS) antenna, the spatial component of signals processing is equivalent to summation and is accomplished at the field level. In case of a uniform circular or sector rotation of the antenna and a point reflecting object the signal of backward scattering at the output of a coherent radar receiver is amplitude and phase modulated by a complex (amplitude-phase) directivity diagram (DD) of the antenna. If a single transmit-receive antenna is used, then amplitude-phase modulation of the received signal is described by the squared complex DD. An interpretation of antenna tuned to scan a fixed direction is known as a spatial filter. Then the uniform scanning antenna can be considered as a sequential analyzer of special frequency spectrum with a tunable scanning filter, and modeling function - as the evaluation of the complex angular spectrum of the combined signal. Taking into consideration unambiguity of direct and reverse spectral Fourier transform, one can conclude about the possibility of unambiguous reconstruction of field distribution over the aperture in the form of a complex spatial signal by means of performing Fourier transform from the complex envelope or modulating function at the output of a phase detector of the radar receiver. The next steps are obvious and consist in application of an algorithm with high resolution over the spectral coordinate to the reconstructed special signal, for example, model-parametric algorithm of spectral evaluation which plays the role of reverse spectral transformation.