Research On Target Distance Information And Amplitude-phase Information Of Multi-carrier Radar Detection System

With the development of radar technology,the application of radar is more and more extensive.Radar detection system plays an increasingly important role in national defense construction and national economic construction.At present,the application of Shannon's information theory in the field of radar mainly focuses on the waveform design of radar detection system.Radar is an information acquisition system.Using information theory to systematically describe and characterize the process of information acquisition,which is of great theoretical significance and application value.So far,many domestic and foreign scholars have explored this,but have not yet formed a unified information theory framework.The multi-carrier radar detection system has higher distance resolution and target detection capability,and is an important direction for the research and development of modern radar technology.In this thesis,we adopt the thoughts and methodologies of Shannon's information theory and use the distance and amplitude-phase mutual information between the received signal and the measured object as a measure to establish an information theory model for multi-carrier radar system.Our research mainly focuses on the distance information and amplitude-phase information of the target.We discuss the single target detection and multi-target detection scenarios and compare with the maximum likelihood estimation method.The numerical simulation results verify the correctness of the theoretical analysis.The main work and innovations of this thesis are as follows:1.Under the complex additive white Gaussian noise channel,we adopt orthogonal frequency division multiplexing signals with subcarrier sequence as Zadoff-Chu sequence to establish a multi-carrier radar detection system model.For the two target models of constant scattering coefficient and Rayleigh scattering coefficient,we analysis the relationship between the detected information quantity and the target parameters by using information theory.Besides,we propose to use Entropy Error to measure the system performance and compare it with mean square error.2.For the single target detection system,we propose definition and description methods of the target distance information and amplitude-phase information under two target models,and derive closed expression of them.The study results show that target distance information and amplitude-phase information will interact with each other,and amplitude-phase information usually depends on distance information.Besides,the amplitude-phase information of the target is only related to the signal to noise ratio but not to the distance information under the Rayleigh scattering coefficient model.In addition,we propose a frequency domain maximum likelihood distance estimation algorithm,which can estimate the time delay of non-integer sampling intervals,and further study the relationship between the distance information of the target and the maximum likelihood estimation.Theoretical analysis and numerical simulation results show that the Cramer-Rao bound of the distance estimation is an asymptotic upper bound for distance information at high signal to noise ratio.The research in this thesis finds that the distance information of the target can be used as the upper bound of the performance of the maximum likelihood estimation,which provides a theoretical basis for the detection performance of the actual system.3.For multi-target detection system,we analyze the distance information and the amplitude-phase information of multi-target when there is no interference between targets,and prove that the multi-target information quantity is the sum of the information of each single target detection information.In the case of two targets,we use the singular value decomposition method to analyze the distance joint information between the two targets when there is interference between the targets.Besides,we derive the Cramer-Rao bound of the joint estimation of distance under the Rayleigh scattering coefficient model.Finally,we propose the definition of distance resolution from the perspective of information theory.The theoretical analysis results break the limitation of bandwidth to distance resolution.