Research And Implementation Of Long-time Accumulation Algorithm For Passive Radar

In the signal processing of passive radar,long-time coherent accumulation of target echo signal can effectively improve the target echo’s signal-to-noise ratio,and then improve radar’s ability to detect target.However,when the target speed and maneuverability is high,long-time coherent accumulation will cause range migration and doppler migration effect in target echo,which will lead to the degradation of the traditional coherent accumulation method’s performance and affect radar’s detection power.Therefore,how to solve the maneuvering target’s migration problems in longtime coherent accumulation of passive radar is the focus of this article.First,under the passive radar echo model,the signal processing flow is summarized.And from the perspective of matched filter,causes of range migration and doppler migration and their adverse effects are analyzed.Then,for the range migration problem of target moving at a constant speed during long-time accumulation,the range migration correction methods of Radon Fourier transform and Keystone transform are studied.Radon Fourier transform is a correction method based on target distance-speed search,while Keystone transform does not require parameters search.It isn’t limited to a priori information such as the number of targets,range,speed etc.,and has better practicability.Therefore,three implementation methods of Keystone transform are analyzed in detail:sinc interpolation,DFT-IFFT,Chirp-z transform.And the performance of three methods are simulated and compared.Finally,a fast implementation method of CZT based on graphics processor is proposed.The measured data verifies the real-time and effectiveness of this method.Finally,based on the correction of range migration,for doppler migration problem of uniformly variable motion targets,three doppler migration correction methods are studied:dechirp,fractional Fourier transform and conjugate time reversal transform.First,the basic principle and main contents of these methods are introduced.Second,the effectiveness of the algorithm and the effects of different parameters on each method are analyzed through simulation experiments.Then,these methods’ applicability and performance are analyzed when dealing with multiple targets.Finally,a brief overview about the application conditions and shortcomings of each method is described.