| Airborne early warning radar has the advantage of "standing high and seeing far".The core technology of moving target detection based on low altitude visual suppression of groundsea clutter is space-time adaptive processing(STAP)technology,which can realize real-time detection and stable tracking of moving targets on the ground or in the air under complex terrain and landform environment.This thesis is based on shielding the transfer of our ground forces,protecting our important targets,carrying out research on effective jamming technologies against airborne early warning radars,analyzing the design and implementation methods of multi-dimensional complex modulation jamming,in order to reduce the target detection performance of enemy airborne early warning radar significantly.Aiming at the necessary conditions of the airborne early-warning radar STAP technology to the training samples of freedom and independent identical distribution,the time-domain modulated nonuniform jamming technology is firstly studied,and then the space-time combined jamming technology is designed to realize the effective jamming of the airborne early-warning radar.The main contents can be summarized as follows:1.In order to solve the problem that classical time-domain modulated jamming destroys the uniformity of clutter environment,the characteristics of many kinds of barrage jamming and deceptive jamming are analyzed.Firstly,the principle and process of active barrage jamming are introduced,and the influence of key parameters on its jamming characteristics is studied.Secondly,the principle of active deception and the working principle of digital radio frequency memory are introduced,the principle and process of several classical deception jamming generated based on digital radio frequency memory are analyzed,and the characteristics in time and frequency domain and the deception and suppression effect on radar are studied.Therefore,the appropriate jamming style can be selected by controlling the key parameters of jamming according to the specific combat environment.2.Aiming at the problem that classical time-domain modulated jamming could not efficiently destroy the uniformity of samples,a design method of jamming modulation based on time-frequency domain Fourier transform was proposed.The time-frequency distribution,suppression and spoofing effects of jamming signals and their relationship with jamming modulation parameters were analyzed.Firstly,the time-domain broadening interference and time-domain compressing interference are introduced based on the scale transformation property.According to the signal form,the appropriate interference signal can be generated by controlling the rate and length of upper and lower sampling.Secondly,the time-domain product modulated jamming is introduced based on the time-domain product theorem.The jamming effect and characteristics of such jamming are affected by the modulated signal.Finally,the time-domain convolution modulated jamming and frequency-domain product modulated jamming generated by time-domain convolution theorem are introduced,and the jamming effects and characteristics of these jamming are analyzed and compared under different modulated signals.Thus,according to different combat scenes,a certain jamming type can be selected,and a good jamming style with dual effects of deception and suppression can be generated by selecting appropriate modulation signals.3.In view of the jamming problem of STAP caused by the combination of multiple jamming stations,the jamming timing design method of random noise timing sequence and random false target timing sequence is analyzed.Combined with space multi-station jamming,the space-time combination jamming design method is proposed,and the jamming effect of sidelobe distributed jamming on airborne early warning radar STAP is studied.According to the proposed jamming timing sequence,the appropriate jamming patter is selected,by comparing the output of signal-to-interference-plus-noise ratio,the average number of targets detected and the average number of false alarms detected after constant false alarm detection,the jamming effect of side-lobe distributed jamming on STAP is analyzed from three aspects of station numbers,angles,and the combat modes.Simulation proves that the appropriate number of stations,angles,combat modes and jamming timing sequence can effectively interfere with STAP by side-lobe distributed jamming,generally,coordinated operations will lead to the attenuation of jamming power,so the jamming effect of independent operations is relatively better.And transmitting jamming with timing sequence2 makes the sample less satisfied with the conditions of independent identically distributed,thus improving interference effect.The correctness of the above conclusions is further verified by the measured data. |
