Unmatched Filters for Autocorrelation Function Side-Lobes Suppression of Complex Radar Signals

Abstract

Requirements for modern radar systems make it necessary to use complex signals. Signal compression during the filtering gives rise to side lobes that can mask the wanted signal and cause false alarms. Lowering the side-lobe level of the autocorrelation function allows solving the problems of detection and resolution of objects with a low effective scattering surface, negative contrast and high interference level. There are hardware and signaling methods to reduce the level of the side lobes of the autocorrelation function. This article studies the hardware methods for reducing the side-lobes level by using an un-matched filter. It describes a method for constructing an inconsistent filter for maximizing the main lobe level with a given level of side lobes. Mathematical modeling of this filter for sequences of phaze manipulation signals, generated on maximum length sequence, was made and illustrated