Signal processing in recursive rejection filters in the transient mode

Authors: DMITRII POPOV, SERGEY SMOLSKIY

Abstract: A recursive rejection filter (REF) oriented to the radar signal extraction from the moving targets on a background of passive interference in the form of undesired re ections from fixed or slowly moving objects (so-called clutter) is the object under investigation. By means of the state variable method, which gives the adequate filter description in the time domain, the REF structure in the transient mode is synthesized, which is improved with the aim of transient acceleration with the clutter edge arriving. The REF structure's improvement in the transient mode is achieved by its reconfiguration, which is made by REF output and feedback switching. The steady-state values of decorrelated rejection residues from the nonrecursive REF part are passed to the REF output and to feedback circuits, which practically eliminates a "ring" in the feedback circuits, which is caused by the mean value and uctuations of the clutter samples, and significantly accelerates the transient at the REF output. The structure diagram of the reconfigurable RF in the transient mode by means of recursive couplings switching is offered. A solution of transient acceleration problems for recursive REFs allows substantive utilization of required characteristics of REFs and their exible control. A comparative analysis of clutter REF rejection effectiveness of fixed and reconfigurable structures is performed in the transient mode. It is shown that REF structure reconfiguration by means of recursive coupling switching essentially reduces the transient duration in the filter and increases the clutter rejection effectiveness in the transient operation mode.

Keywords: Efficiency analysis, acceleration, clutter edge, structure reconfiguration, rejection filter, state variable, transient

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