Research On High Speed Target Detection Method Of Wide Pulse LFM Wideband Radar

With the rapid development of ballistic missile and high-speed aircraft,high-speed moving target detection becomes one of the important tasks of radar.Wideband radar has more advantages in motion parameter estimation and target recognition with higher range resolution and more target feature information.Therefore,the research of high-speed moving target detection based on wideband radar has important application value and bright application prospect.In order to improve the detection and resolution ability of radar for high-speed targets,it is usually required that the transmitted signal of radar has a large time bandwidth product,which leads to an increase in the amount of echo data that needs to be processed and the computational complexity of existing detection algorithms.In order to make better use of wideband radar in practical application,the performance impact brought by its large bandwidth to high-speed target detection needs to be solved.This thesis mainly studies the detection of high-speed moving targets under large time bandwidth product signals.The echo model of high-speed moving target based on single wideband pulse is established,and the effects of parameter estimation methods in different analysis domains on the detection performance of high-speed targets are compared.Finally,the coherent accumulation of target is carried out by using two-dimensional IAA spectrum estimation algorithm to improve the detection performance of target further.The main contents of this thesis are summarized as follows:1.The high-speed target detection under wideband conditions is studied.Firstly,the echo model of high-speed moving target with single broadband pulse is modeled,and the detection of range and velocity of high-speed target is transformed into the estimation of center frequency and frequency modulation slope of LFM signal by mixing the received echo with the transmitted signal.Secondly,the parameter estimation methods of LFM signal in different analysis domains are introduced,and the principle and implementation of Wigner-Hough transform(WHT)algorithm in time-frequency domain analysis are explained.Finally,simulations verify the effectiveness of WHT algorithm for high-speed target detection and the problem of large computational complexity.2.Considering that the detection method based on time-frequency domain needs secondary conversion and unknown parameter search,aiming at the problems of large amount of data computation and cross term interference,a high-speed target detection method based on Centroid Frequency-Chirp Rate(CFCR)domain is studied.Firstly,the detection principle and three implementation methods of Lv's Distribution(LVD)algorithm are introduced,and the feasibility and accuracy of the LVD algorithm for detecting multiple high-speed targets under the condition of low signal-to-noise ratio are verified by simulation.Then,the Coherent Integral Cubic Phase Function(CICPF)and Non-uniform Fast Fourier Transform(NUFFT)are applied to high-speed target detection of wideband radar.The principle and implementation of CICPF algorithm and NUFFT algorithm are described in detail.The effectiveness of CICPF algorithm for high-speed target detection under low SNR condition and the feasibility of NUFFT algorithm for improving operation efficiency are verified by simulation.Finally,combined with the fixed delay of LVD algorithm and CICPF algorithm,a high-speed target detection method based on Parameterized Centroid Frequency-Chirp Rate Distribution(PCFCRD)algorithm is proposed.The simulation results show that PCFCRD algorithm is superior to LVD algorithm and CICPF algorithm in target detection,cross term and noise suppression,and has low computational complexity.3.Aiming at the problem of wide main lobe and high side lobes in the high-speed target detection results of PCFCRD algorithm,a high-speed target detection method based on PCFCRD algorithm and two-dimensional IAA spectrum estimation is studied.It is verified by simulation that the algorithm combining PCFCRD and two-dimensional IAA can suppress side lobes well,reduce the width of the main lobe,and improve detection accuracy.The signal sampling rate and the amount of echo data increase with the target speed improving,in order to improve the speed and accuracy of target detection,the twodimensional IAA super fast algorithm is derived on the basis of the two-dimensional IAA fast algorithm based on GS decomposition,and a high speed target detection method based on two-dimensional IAA super fast algorithm is proposed.The simulation results show that this method not only narrows the main lobe width and reduces the side lobe of the target spectrum,but also reduces the amount of computation by order of magnitude,which greatly improves the efficiency of the operation.