| The radar seeker has been widely used in missile guidance field because of the range coverage of it is far and can work around the clock.However,the radar seeker faces a electromagnetic jamming environment which is complex and changing,making the anti-electronic jamming ability and low probability of interception become the important indicators.Because MIMO radar has obvious advantages in anti-target "flickering",anti-jamming,reducing the probability of radar interception,and improving the ability to detect weak targets,it becoming the development direction in modern radar.By applying the MIMO radar into the radar seeker,can further improve the overall performance of the radar seeker.The waveform orthogonality of MIMO radar affects the system performance directly.In this thesis,We design the waveform of the transmitted signal of the MIMO radar seeker.The character of Time-sharing orthogonal frequency-coding waveform is each array element emits a chirp signal with the same frequency band,which can satisfy the requirements of phase-parameter processing and the Doppler tolerance is high,by using orthogonality in Time-sharing frequency diversity,make it better than traditional MIMO quadrature waveforms.Then the signal processing of the MIMO radar seeker is designed.The key of MIMO radar signal processing is to recover the echoes of the transmitted signals of each array element.Therefore,a set of channel separation methods is designed according to the characteristics of the transmitted signal waveform and the structure of the guided radar array.First,Separate the echo signal of each element and the echo signal of other elements through different band-pass filters.Then,a spectrally continuous synthetic chirp signal is obtained after delay and spectrum splicing,so that the pulse compression processing of the conventional LFM can be used to complete the the pulse pressure of the synthesized signal.Finally,analyze the anti-jamming method of the MIMO seeker,mainly for the identification or suppression of three types of jamming,including active masking jamming,delayed repeater deceptive jamming,and partial sampling direct repeater deceptive jamming.Among them,when there is a side lobe active suppressive jamming,we adapt beamforming method to suppress it;when there is delayed relay deceptive jamming,the steering vector of the jamming component in output signal will change with delay different delays,different emission-oriented vector rights are used to make beam forming,and the true and false targets can be discriminated by comparing the changes in the target amplitude in the output signal;when there is a partial-sample direct-directive deceptive jamming,the jamming is caused by the jammer.The pulse width of sampling and interception is small,and the jamming signal occupies a very small frequency bandwidth.Therefore,the echo signal can be divided into two frequency bands by a band-pass filter,and then the two pulse voltages are processed respectively to calculate the same position target.The ratio of the peak,and according to the criterion can be identified true and false goals.Through simulation experiments,it is verified that the Time-sharing orthogonal frequency-coding waveform not only can separate the echoes about transmitted signals of different array elements through frequency domain filtering,but also ensure that isolation between the transmitted signals of each array element can reach more than 50 d B;the signal processing can successfully separate the echoes about transmitted signals of each array element and can solve the distance and angle information between the missile and the target.The anti-jamming method can effectively identify or suppress the corresponding jamming.It is a good theoretical basis for engineering implementation of MIMO radar seeker. |
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