Study Of Adaptive Low Probability Of Intercept Radar Waveform Control Methods

Low probability of intercept(LPI) radar gets a lot of attention in the field of modern radar because it plays an important role in electronic countermeasure(ECM), the development of low intercept technology greatly enhance the survivability of radar in military operations. While the increasingly complex electromagnetic environ- ment puts forward new requirements for low intercept technologies, hoping that radar system can adjust the launch waveform according to the change of targets and environment to achieve better intercept factor. The application of adaptive technology in radar system is becoming more and more mature make it possible, as well as the development of cognitive radar. In this paper, we studied the adaptive control technologies of LPI waveform, then analyzed the adaptive waveform design methods geared to the needs of target detection. This paper carried out the flowing tasks:1. Researched the clutter distribution model which can describe the radar environmental characteristics, also the parameter estimation method. Then analyzed the radar target characteristics based on the target echo model, discussed four classic target detection algorithms and the target detection algorithm based on the analysis of echo statistical characteristics. In the final, we researched the parameter estimation of LPI signal, as well as the emulation analysis.2. Introduced the frequency-modulated signal phase-modulated signal based on the intercept factor, which are the two types of LPI signal. We researched compound modulation signal to solve the problem which the modulation of basic signal is too simple, then analyzed its intercept factor according to simulation result. Discussed the application of chaotic mapping in waveform design, and the performance of the chaotic signal.3. Studied the traditional adaptive waveform control method from three aspects, which are adaptive waveform selection, adaptive waveform design and suppress clutter jamming waveform design method. We analyzed two adaptive waveform selection methods, the reverse dynamic programming algorithm and the Q-learning method, then the advantages and disadvantages of this two methods were analyzed through comparative simulation. Introduced adaptive waveform design optimization method based on ambiguity function, then analyzed the effectiveness of the algorithm in enhancing the intercept factor of OFDM signal. At last, we introduced an adaptive waveform optimization method of clutter suppression according to the probability density function of clutter.4. Researched a method of adaptive launch waveform, adjust the next launch waveform using the echo information of the last launch, which is different from the fixed emission waveform using in traditional radar system. Then proposed an adaptive waveform design methods geared to the needs of target detection, and the detection performance of the method, as well as the fixed emission waveform method using in traditional radar system, is analyzed through comparative simulation.