The Radar Lfmicw Altimeter Earth Echo Modeling And Simulation

Linear Frequency Modulated Interrupt Continuous Wave (LFMICW) system has advantages of both continuous and pulse wave radar systems. When LFMICW is used into altimeter, it can avoid problems like wave isolation caused by continuous wave in transmitting and receiving and the very high peak power by pulse wave.In order to provide simulated data source for LFMICW radar altimeter height detection algorithm, terrain return of LFMICW altimeter needs to be modeled and simulated. Radar target environment needs to be deeply studied to improve properties of height detection algorithm, thus terrain return properties need to be analyzed and studied. The detail tasks referring to the thesis are as follows:1. LMFICW signal waveform is analyzed. Mathematical model of LFMICW return from single scatterer is proposed through analyzing factors affecting return from single scatterer. LFMICW return from single scatterer is simulated and analyzed.2. Factors affecting LFMICW radar altimeter terrain return are studied, including the ratio factor of specular component to scatter component, average power of terrain return, scattering coefficient model, antenna directional pattern and Doppler shift of terrain return. Important factors are simulated and analyzed.3. The distribution of equidistant circles and equal-Doppler spaces are studied. Based on this study, terrain is mesh partitioned into multi scattering units.4. LFMICW terrain return model is established; return and beat signal is simulated and return data is obtained. Terrain return signal characteristics under different ground conditions, different height and different SNRs are studied.5. Different types of disturbance are analyzed. LFMICW terrain return with different disturbance under different signal-disturbance ratio is simulated and analyzed.This paper conducted a study into terrain return characteristics of LFMICW radar altimeter. The simulation results and analysis provided by this paper is the foundation of LFMICW radar altimeter system design and height detection algorithm study.