Research On The Jamming Technologies Of Missile-borne Synthetic Aperture Radar

Ballistic missile and anti-ship missile gradually equip Synthetic Aperture Radar(SAR) precise guidance seeker to improve the accurate attack effect, when facing with an increasingly complex electromagnetic environment. The SAR seeker improves the error correction accuracy of trajectory, probability of target detection and recognition by using a series of measurements, such as scene and typical target matching. For countering missile-borne SAR precision-guided seeker, improving the capability of ship target to evade missile strike and the viability of the complex battlefield environment, some ship-borne electronic countermeasures are discussed in this dissertation. Firstly, according to the application characteristics of the missile-borne SAR, we analyze the essential parameters when generating suppress jamming and deceptive jamming signals, and also analyze the effects of the parameters error on the jamming affects. Secondly, some coherent suppress jamming technologies, false target and large scene deceptive jamming technologies are discussed. And finally, we also make some analysis on suppress jamming and deception jamming technologies for countering missile-borne linear frequency modulated continuous wave(LFMCW) SAR system. The main contributions of this dissertation are as follows:1) In order to detect the effect of parameter errors provided from electronic surveillance system on the jamming effects, we analyze the gain of noise signals through SAR two dimensional pulse compression processing, and extract the parameters when generating the noise suppress jamming signals for countering missile-borne SAR, such as instantaneous slant range, transmitted signal power and SAR system parameters. We also study the jamming signal ratio effects of the error noise jamming signals. We analyze and extract the essential parameters such as spatial position, velocity, transmitted signals of missile-borne SAR, when generating deceptive jamming signals. And we study the deceptive jamming effects introduced these parameter errors on the position, amplitude, and resolution of the false target. And the proposed jamming methods solve the problems about the guided parameters precision when generating suppress and deceptive jamming signals.2) In order to improve the pulse compress gain of suppress jamming signals and reduce the power of transmitted jamming signals, we analyze the pulse compression output of multiplicative noise jamming signals and convolutional noise jamming signals, and point out the theoretical basis of the coherent noise jamming signals which could improve the pulse compression gain, and propose a coherent noise two dimensional suppress jamming technology. Based on the time-dependent characteristics of sea clutter, we establish several types of mathematical model about sea clutter and propose a jamming method about coherent amplitude sea clutter modulation to the intercepted missile-borne SAR transmitted signal. According to the effect that the pulse compression mismatch could broaden the peak output, we propose a two dimensional mismatching suppress jamming method by modifying the chirp rate and the Doppler frequency of the intercepted missile-borne SAR transmitting signals. The proposed suppress jamming methods improve the pulse compress gain and reduce the power of transmitted suppress jamming signals.3) A deceptive jamming signal generation method based on phase modulation of false target template for countering missile-borne SAR is proposed to improve the real-time ability when generating deceptive jamming signals. We analyze the Doppler frequency of the jammer and the false target. The deceptive jamming signal is rapidly generated by modulating the difference of Doppler frequency of the jammer and the false target. Using motion frequency modulation to the azimuth direction Doppler frequency, the jammer modulates a linear frequency modulation(LFM) signal the intercepted missile-borne SAR transmitting signals to generate a similar vessel false target deceptive jamming. The proposed methods reduce the computational complexity, and improve the real-time ability when generating deceptive jamming signals.4) According to Geometric Theory of Diffraction, the weak scatters enhanced template and surroundings enhanced template are generated and modulated to the intercepted missile-borne SAR transmitting signals, which could generate multiple false targets deceptive and large scene deceptive jamming. The false target and scene change the SAR image characteristics of weak scatters, and surroundings of vessels, which could reduce the detection and identification probability of missile-borne SAR target recognizer.5) Referencing the dechirping process of missile-borne LFMCW SAR, we propose a deceptive jamming method that is similar to dechirping process to the intercepted missile-borne LFMCW SAR transmitting signals, and inverse dechirping process to recover the wideband of jamming signal to equal the bandwidth of the intercepted missile-borne LFMCW SAR transmitted signal, which reduces the bandwidth of the intercepted signal, analog to digital conversion rate of the receiver, and the data processing amount of jamming signal generation. The similar dechirping process also improves the real-time ability when generating jamming signal for countering missile-borne LFMCW SAR.