| Cognitive radar has received worldwide attention since it was offered, because it can adapt to the increasingly complex detection environment. Cognitive radar has an information feedback mechanism from the receiver to the transmitter. Using perceived information and other prior knowledge, cognitive radar executes adaptive design of the transmitter and receiver to realize the sensing and tracking of the goal, reliably and robustly, so that the radar system’s performance can be improved. Now, the idea of cognitive radar has been extensively used and spread. The concept of cognitive behavior has been included in various studies. Prior information participates in the process of signal processing to enhance the performance of the system.Cognitive radar interacts with the environment, adjusts the system adaptively and uses the most appropriate system configuration(including frequency, form of signal,etc) to match with the external environment and the target state, so that the radar system can get the best performance. As for the airborne radar, the first part is a more in-depth study for airborne radar parameter optimization based on cognitive radar. Pulse repetition frequency is one of the most important resources of the radar transmitter. Radar can effectively reduce blind area by using the appropriate pulse repetition frequency group to improve detection performance. Because of the aircraft’s flight, radar’s background changes at any time. So, how to optimize the radar pulse repetition frequency to match the specific radar work background is an important topic which airborne cognitive radar requires an in-depth exploration. Based on previous research, this thesis does a study and analysis on the model of pulse repetition frequency optimization which was existed. The thesis finds out the deficiency of the original research: the scenario where a strong urban clutter enters into radar system from airborne radar antenna side-lobe is not given a comprehensive consideration. In view of the deficiency, establish the corresponding search model, consider the effect of the velocity ambiguity and range ambiguity, improve the optimization algorithm which is based on genetic algorithm, search for the corresponding optimal pulse repetition frequency group.Space time adaptive processing is a significant method to suppress the clutter and to improve the detection performance for airborne radar. The thesis proposes a new space time processing method with the FIR filter on the basis of the existing two-dimensional space time adaptive processing theory: Design the clutter suppression FIR filter based on those clutter prior information. Use this filter to filter the echo signal in the time domain, then do the space time combined processing. The method has obvious improvements compared with the previous method. |
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