Research On Radar Coincidence Imaging Technology In Low SNR

Radar coincidence imaging is a new method of high resolution staring imaging, whose imaging algorithm in low SN R is a difficult problem with important theoretical significance and practical value. The paper focuses on the radar coincidence imaging experiment system which is being built, establishes the radar imaging model in the presence of noise, and analyzes the influencing factors affecting the estimated error and the noise environment of the experiment system, then researches the accumulation methods of pulses for stationary targets and moving targets when the SNR is low, providing a theoretical reference and method guidance for experimental system to achieve the goal of accurate reconstruction in low SNR.In the introduction, the paper firstly introduces the background and significance of issues associated with radar coincidence imaging, then elaborates the history of the emergence and development of radar coincidence imaging, and finally presents the work and organization structure of the paper.In the second chapter, the basic theory of radar coincidence imaging is expatiated. The process of radar coincidence imaging consists of three main parts: First, each array element of the radar arrays transmits a set of random signals. Then the 2-D radiation field including random time and space in the position of the targets is formulated. Finally the radiation field and the echo signal are associative processed to obtained Reconstructive image of the targets.In the analysis of radar coincidence imaging errors in the presence of noise, the paper firstly establishes the parametric model in noisy condition, and find the estimated error is associate with the SNR, the signal bandwidth, the target complexity and the time delay of echo signal by theoretical derivation, the simulation results verify the correctness of the above views. Finally the paper calculates the noise level of emit channel and receive channel according to system parameters and provides noise priori for sparse algorithm.In the study of radar coincidence imaging algorithm in low SNR, the paper analyzes the applicability of the sparse reconstr uction algorithms to radar coincidence imaging in low SNR, then analyzes the effect of coherent integration of stationary targets to find the excellent agreement between simulation and the theoretical analysis result, and finally presents the coherent integration method of moving targets, explaining the reason why the pulses accumulation did not get SNR gain, and gets the conclusion that a certain number of pulses accumulate can be improve reconstruction quality of the moving targets.In the last part, the work of the dissertation has been summarized, and next step of the study has been presented.