Robust Space-Time Beamforming Method and System for Airborne Radar under Steering Vector Mismatch

Abstract

The invention provides an airborne radar robust space-time beam forming method and a forming system under steering vector mismatch. The method comprises steps: a flight altitude and a speed of an airborne platform and an arrival angle of a target echo signal are initialized, and a Doppler frequency of a radar echo signal is determined; a receiving signal model for an array antenna is built and according to the arrival angle of the radar echo signal and the estimation value of the Doppler frequency, a space-time integral covariance matrix is built; according to the space-time integral covariance matrix, clutter plus noise subspace is determined; a target function and constraint conditions for a steering vector estimator are built, and according to a semi-definite programming relaxation method, the actual steering vector of the target echo signal is solved and obtained; and according to a minimum variance distortionless method, a weight coefficient for the array antenna is acquired. The optimal estimated value of the expected target steering vector can be acquired, a beam former succeeds in suppressing clutters and forms beams only in the expected target direction, amplification of noise power is avoided, and the output signal to noise ratio of the beam former is thus expanded.

Description

technical field [0001] The invention relates to the technical field of array antennas and airborne radars, in particular to a robust space-time beamforming method and system for airborne radars under steering vector mismatch. Background technique [0002] The main task of airborne radar is to identify and track the desired target in a complex background environment. Therefore, it is necessary to form a null at the ground clutter and form a beam at the target. Due to the movement of the airborne platform, the ground clutter spectrum of the airborne phased array radar shows the characteristics of main clutter broadening in the Doppler frequency domain. In addition, the ground clutter spectrum has a coupling relationship in the space domain and the time domain. Neither conventional time-domain nor space-domain filters are capable of forming a notch that matches ground clutter. Space-Time Adaptive Processing (STAP) technology can jointly suppress ground clutter from two-dimens...

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Problems solved by technology

[0006] In view of the deficiencies in the prior art above, the purpose of the present invention is to provide a robust space-time beamforming method and system for airborne radar under mismatched steering vectors. When there is a deviation in the Puler frequency estimation, the output signal-to-noise ratio performance of STAP will be severely degraded

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