Research On Maneuvering Target Tracking Techniques In Digital Array Radar

Compared with phased array radar,digital array radar is a newer kind of radar systems.Due to its superiority of all-digital processing,a larger dynamic tolerant range is achieved.It is able to detect small targets in a strong clutter environment.With digital beamforming(DBF)technique both in transmitting and receiving,better antenna beam performance is obtained,which is with a lower sidelobe.Thereby,it has a more excellent system detecting and target tracking ability.Therefore,it has attracted increasing interests of researchers around the whole world.This paper is focused on researching a digital array radar system to improve its effective range and tracking accuracy,utilizing classical radar signal processing methods,target tracking theory,and strapdown decoupling technology into typical combat scences.An intensive study is exhibited in this paper about maneuvering target tracking techniques in digital array radar systems.The main contents can be summarized as follows:1.Due to the unsatisfying performance of velocity trakcing loop in a digital array radar,a velocity tracking loop design method of CPAFC with loop filter(CPAFCLF)is proposed in this paper,which achieves close-loop control of output error at the frequency discriminator,and the convergent rate of velocity tracking error is accelerated.Simulations under scenes of different signal-to-noise ratio(SNR)in the velocity tracking loop demonstrate its excellent dynamic tolerant scope of SNR.2.For range tracking methods in digital array radar systems,as target's maneuvering frequency and acceleration limits can not be preset accurately in classic "current" statistical model(CS),an adaptive "current" statistical model with velocity prediction(ACSMVP)algorithm for range tracking is put forward with CPAFCLF method.It achieves an adaptive value of process noise covariance matrix.Then,an improved algorithm called Sage-Husa-based ACSMVP(SH-ACSMVP)is also proposed,promoting the performance of range tracking in digital array radar systems.Simulations in a typical scene of target tracking highlight the superior performance of SH-ACSMVP over existing methods.3.A problem of range eclipsing exists in the digital array radar of a high pulse repetition frequency pulse Doppler(HPRF-PD)system.It deteriorates the steady target tracking ability of radar systems.Therefore,a novel waveform selectioin strategy is designed.Using the proposed pulse repetition frequency(PRF)selection strategy,a waveform lookup table concerning range and PRF is obtained off-line.With SH-ACSMVP,a predicted radial range is achieved for next coherent processing interval(CPI).Therewith,the transmitting waveform for next CPI is chosen from the PRF waveform lookup table.The subsequent target tracking performance is then enhanced.Simulation results show the correctness and effectiveness of the proposed waveform selection strategy in this paper.4.Angle tracking loop is the most important tracking loop in the digital array radar.It is significant to obtain stable tracking performance.An algorithm called constant coefficient angle tracking loop filter(CCATLF)is proposed in this paper.It improves the angle tracking performance.Considering that the equivalent loop noise bandwidth is related to target's maneuvering status,two angle tracking algorithms based on corner detection are put forward.Moreover,two angle tracking issues occur when a digital array radar tracks a maneuvering target:slow convergence in the beginning stage of tracking,and a divergent issue of tracking errors at the final tracking phase.The improved algorithm is called adaptive angle tracking loop filter(AATLF).With theoretical derivation,a relationship formula between the output angle tracking error variance and the SNR of signal in the angle tracking channel is established.Meanwhile,a proof is given that the stability of the proposed angle tracking loop is not related to the equivalent loop noise bandwidth.At last,with sufficient simulations,the four proposed algorithms are compared,which indicates that AATLF has the best angle tracking performance and the widest application.5.For missle-borne or airborne digital array radar systems,the beam direction of the antenna plane in a digital array radar is heaviy affected by the disturbance of radar platform attitude.The stability of angle tracking performance is then deteriorated.Thus,it is vital to research and develop strapdown decoupling algorithms for digital array radar systems.Inspired by the methodology of angle tracking loop design in this study,in association with typical strapdown decoupling method(SDM),two new algorithms called SDM based on loop filter(SDMLF)and SDM based on adaptive loop filter(SDMALF)are put forward.Simulation results are given to verify the stability and effectiveness of the proposed methods.At last,combining with applicational requirements and the available semi-physical simulation platform system in our laboratory,such two strapdown decoupling algorithms are transplanted into practical signal processing boards.The actual experiment results have verified the feasibility and usefulness of the proposed methods.