.fsk / Psk, The Echo Signal

This dissertation is the expansion of the project of the National Natural Science Foundation of China (NSFC) named for"producing and processing the new multi-modulation signal of the sensor with strong detectability and recognizability". The purpose of this study is to model and simulate the new multi-modulation radar signal returns. The results can be used for the further research on the signal and the signal simulator. This study is supposed that the FSK/PSK signal is applied to ground-based searching radar, and the radar video returns which are modeled and simulated consist of target returns and clutter returns.In the first chapter, firstly, the background of this study is introduced, then, we summarized the latest study of the FSK/PSK signal and the radar signal modeling both in internal and overseas. In the second chapter, the base theory knowledge of the radar signal modeling is introduced, some of simulation model which will be used in this dissertation are also introduced. The clutter modeling is the most important process during the simulation, so in the third chapter, the coherent clutter modeling is separately discussed and the simulation results are presented in the following. After that, the probability density characteristics and the spectral density characteristics of the generated clutter data are analyzed. In the fourth chapter, firstly, the FSK/PSK signal function is presented, then, the signal which frequency and phase are modulated by Costas code and Barker code for each are analyzed at the same time. After that, the target returns and clutter returns are analyzed and modeled. At last, both of the time correlation characteristics and space correlation characteristics are theoretically analyzed. A result is acquired that the time correlation characteristics of the FSK/PSK radar clutter is invariability, but the space correlation characteristics is enhanced. In the fifth chapter, we apply the FSK/PSK signal to the ground-based searching radar system, then the radar returns are simulated and the simulation results are presented. In the end of the dissertation, the results of research are summarized.The summarization of this dissertation:...