Research Of The Radar Target Detection Algorithm Based On FRFT

Radar target detection technology has high application value in both military and civilian areas,and it is one of the most important tasks of radar to improve the reliability of the target detection.For the detection of weak targets in the sea clutter background,the traditional method is to use the appropriate statistical model to model the sea clutter from a statistical point of view to realize the automatic detection of radar target.However,in the complex sea clutter background,the statistical model can not reflect all the characteristics of sea clutter.In the time frequency analysis method,if the frequency information of the target can be extracted,the target echo can be approximated as LFM signal,and the fractional Fourier transform is very suitable for dealing with such non-stationary signals.Therefore,this paper mainly studies the algorithm of radar target detection based on fractional Fourier transform,combing with fractal theory,so as to improve the detection of moving targets.Firstly,the definition and time-frequency characteristics of FRFT are given,and a fast discrete method is introduced.Then,three methods of estimating the optimal order are discussed,especially the method of calculating the central moment of the fractional domain.This method can find the best rotation angle more intuitively and do the preliminary work for the detection.Secondly,the target detection is realized by using FRFT to differentiate the energy of the sea clutter and the target echo signal.The radar echo signals are modeled based on the Doppler effect.The IPIX radar data and statistical model fitting analysis are introduced,and the sea clutter under different statistical models is tested and verified.Aiming at the problem of detection capability degradation in low SCR,the method of shift cancellation is proposed,which is based on difference of FRFT modules of echo signal and its time-lapse signal to improve the detection ability.Among them,the influence of delay time on detection is analyzed in detail.Finally,the target detection is carried out by using the spatial difference of FRFT domain.Using FRFT for pretreatment,SCR is improved in its best transform domain,and using wavelet Hurst index method to calculate the Hurst index of target cells and sea clutter in fractional domain of IPIX radar data.According to different Hurst index of different distance units,the effective distinction between sea clutter and target echo is realized.And the selection of the best rotation angle is analyzed emphatically.Subsequently,compared with the time-domain fractal,it is proved that the FRFT preprocessing performance is higher than the time-domain fractal at low SCR.