The Method To Correct The Ionospheric Phase Distortion Of The Travelling Radio Wave

With explosive growth and integration of many interfacing discipline, such as communication, computer science, space science, marine sciences, geosciences and so on, people have made the most use of the ionosphere to establish long distance communications, over-the-horizon detection and extensive navigation. Therefore, ionosphere has played an increasing role in people's routine life. Meanwhile, because of the complexity of the ionosphere, the wave that travels in it will be inevitably affected. For instance, owing to the phase distortion, the spectrum of the wave might be stretched, which would greatly influence the detection of the target. In order to enhance the ionospheric adaptability and the anti-jamming of the system, it is necessary to make a study on the correction technique of this problem.The thesis consists of the bellowing parts:1. The brief of the ionosphere. The outline of the ionosphere has been given from seven different parts——the formation of the ionosphere, the structure of the ionosphere, the Doppler property of the ionosphere, the factors that can influence the ionosphere, the situation of the ionosphere over China, the model of the ionosphere, the measurement of the ionosphere. We might hold a full view of the ionosphere from these information, and get ready for the further research.2. The illumination of the influence of the ionosphere to the wave that travels in it. Since the subject of the thesis is about the wave in the ionosphere, it might be essential to perceive and comprehend how the ionosphere influences the wave. First, it briefly introduce the situations in the case of oblique incidence and scattering of the wave. Secondly, it emphases the influence of the ionosphere to the radar receiving wave, including the changes in the amplitude and the phase and the influence of the function of the HF radar.3. The study of two techniques——the characteristic decomposition algorithm and the phase gradient algorithm (PGA)——to correct the phase distortion of the wave that passes the ionosphere and the simulation and discussion of the two methods. At first, it gives the mathematics model of the phase distortion function. Then it introduces two techniques that can correct the phase distortion. At last, by MATLAB, it simulates the correcting results of the SF signal that simulates the sea clutter and the receiving SF signal that appended with the target information, using the characteristic decomposition technique and PGA technique, and analyzes the performance of the two techniques.