Clutter Modeling And Suppression Method For Airborne Cognitive Radar

Cognitive radars are cycle radar systems,which fully utilize the prior information,the transmitting waveform and the processing mode of receiving signal to make the radar work in the best condition.By applying the idea of cognitive radar to the airborne radar system,the performance of airborne radar can be improved remarkably.Target detection in the existence of clutter is the focus and difficulty of airborne cognitive radar field.In general,the main work and contributions are as follows:1.For the clutter modeling problem of the airborne cognitive radar,two radar systems,uniform pulse repetition period(PRT)radar and non-uniform PRT radar,are considered respectively.For the two radar systems,the characteristics of the theoretical clutter spectrum are analyzed firstly.In addition,the clutter spectrums under several typical scenarios are also discussed.Next,the processes of clutter modeling and signal processing of airborne cognitive radar are deduced,and the range-Doppler(RD)plane of the clutter spectrum is obtained.Finally,the advantages and disadvantages of the clutter spectrums of the two systems are compared in the simulation.2.For the sidelobe clutter suppression problem of the airborne cognitive radar,a clutter suppression method based on cognitive asymmetric beamforming is studied.In the case that the sidelobe of the beam receives strong clutter,the optimal problem of minimizing peak sidelobe level in a specific region is established,along with the mainlobe level constraint,sidelobe level constraint and array gain constraint.Then,the beamforming of the specific scenario is obtained.Finally,the numerical results show the effectiveness of the sidelobe clutter suppression method which suppresses the strong clutter of the region of interest,improving the signal-to-clutter-plus-noise ratio(SCNR)of the target in the region.3.For the mainlobe clutter suppression problem of the airborne cognitive radar,the problem of obtaining prior information is discussed firstly.The target perception method based on iterative sequence estimation method is proposed.Then the RD plane of the target is obtained.Next,adopting the mainlobe clutter distribution information obtained from non-uniform PRT radar and the target information obtained above,the transmitting waveform and receiving filter are designed simultaneously based on the sequential greedy optimization algorithm(SGOA)to establish an optimization problem for minimizing the integrated sidelobe level of clutter(ISLC)in the region of interest.Finally,the numerical results show the effectiveness of the mainlobe clutter suppression method which suppresses the mainlobe clutter of the region of interest,improving the SCNR of the target in the region.