Study On Signal Processing Techniques Of Multi-scan Airborne Weather Radar

Airborne weather radar is designed to detect the weather conditions in the flight and feedback the information to the pilots, such as the intensity and locations of the meteorological targets. Using this information, the pilots could make decisions to select safer routes to avoid the severe disaster weather like a thunder cloud or a strong storm and so on. The multi-scan mode is a new working mode of the airborne weather radar which can provide more comprehensive and more accurate descriptions of the meteorological targets. This thesis studies some key signal processing technologies of the multi-scan airborne weather radar including the simulation of the meteorological echoes, the estimation of the filling coefficient and the reconstruction of the target’s vertical profile. The research work is supported by the Fund of Aeronautics Science and the products can be used in the next generation of airborne weather radar to improve the intelligence level of the systems. The major contributions are as follows:Chapter 1 firstly introduces the research background and significance of this thesis, and then summarizes the domestic and foreign development of the meteorological radar. Finally we introduce the existing problems of the weather radar and analyze the key technology of the airborne weather radar.The second chapter analyzes the characteristics of the meteorological target and deduces the meteorological radar equation. Then we summarize the amplitude and spectrum statistical distribution model of the meteorological echoes, and study a simulation method of the meteorological echoes based on the ZMNL, that is a frequency domain transformation. Finally, we analyze the characteristics of the ground clutter model and study a GMAP method to filter off the ground clutter.In chapter 3, we analyze the change rule of filling coefficient under different conditions, and study an estimation method of the filling coefficient based on radar working parameters. Then we make a comparison of the radar reflectivity factors before and after the introduction of filling coefficient. It can verify the correctness of the estimation method and the importance on improving the radar detection accuracy.The fourth chapter mainly studies the reconstruction method of the meteorological target’s vertical profile based on the multiple scan mode. This paper introduces the multiple scan mode of airborne weather radar, and the method of converting the meteorological dates from the polar coordinates to the rectangular coordinate system. Finally, the paper proposes a reconstruction scheme of the meteorological vertical profile, based on the prior model reconstruction. The simulation analyses prove that the reconstruction method is effective.Chapter 5 is the summary of the research work.