High-Precision Time And Space Domain Parameter Estimation Of Radar Signal Based On Distributed Satellites

Due to the unique spatial position and movement patterns of satellites,information can be obtained from hostile radar signals through carrying devices,thereby obtaining military deployments and electronic intelligence from hostile.Moreover,electronic reconnaissance satellite has wide detection range,high sensitivity,strong maneuverability,wide reconnaissance frequency range,and its operation trajectory is not limited by national and regional factors,making it a research hotspot in electronic reconnaissance.Nowadays,the field of satellite reconnaissance is booming,and satellite electronic reconnaissance is gradually upgrading from single satellite reconnaissance to distributed satellites collaborative reconnaissance.For distributed satellites electronic reconnaissance,the requirements for coverage in time domain,frequency domain,and space domain are increasing,and the requirements for reconnaissance parameter accuracy and reliability are also increasing.However,the electromagnetic environment it faces is complex and the signal-to-noise ratio is low.In response to the above issues,works of this thesis are as follows.1.By utilizing the multi machine characteristics of distributed satellites,signal detection and PRI modulation type recognition on a single satellite are analyzed under the superheterodyne frequency scanning interception architecture firstly.Then,based on the estimation of time domain parameters on a single satellite,feature level fusion of parameters are carried out to obtain accurate signal detection and PRI modulation type recognition results.2.Researching satellite array direction finding methods,while ensuring no ambiguity in direction finding,to maximize the distance between array elements and improve the accuracy of single star direction finding,mainly through the idea of rotation and virtual insertion,using special array configurations and interferometer algorithms,this thesis achieves no ambiguity estimation of DOA.Then,the space domain parameter DOA is fused at the feature level to obtain high-precision direction finding results for the distributed satellites system.3.In distributed satellites,the distance between satellites is much greater than the half wavelength of the signal,the array aperture is large,and the direction finding accuracy can be high.To study the direction finding method of sparse array of distributed satellites without ambiguity,preliminary direction finding is first carried out using the time difference method,and then high-precision DOA search is carried out using MUSIC algorithm and relevant interferometer algorithm respectively,thereby avoiding most of the ambiguity of DOA.And due to the sensitivity of the time difference method to time difference,the impact of time difference error on the non fuzzy direction finding method is analyzed next.4.In order to improve the frequency domain coverage of distributed satellites reconnaissance without increasing the system load and complexity,this thesis studies a frequency domain unambiguous estimation method based on the Chinese remainder theorem and symmetric digital system under the architecture of mutually exclusive sub-Nyquist sampling.The main idea is to make signals of different frequencies fall into different frequency bands through mutually exclusive sampling rates,and the frequency and group codes correspond one-to-one.After obtaining the signal frequency,under this architecture,a study is conducted on the method of obtaining phase interferometer unambiguous DOA,and the MUSIC method direction finding and correlation interferometer direction finding are achieved after interpolation filtering processing.