The Research On TDOA/FDOA Estimation For Double-satellites Interference Source Location

With the rapid development of electronic information,radio communication technology is widely popular,which makes satellite communication technology has become an important direction of development.In the modern military warfare,the coordination and cooperation of the multi-dimensional integration of land,sea and sky need to establish a multi-level,high-complexity and large-capacity integrated communication system.Satellite communication will serve as an important work of coordination,command,communication and control.The satellite communication system intercepts the intentional or unintentional electronic radiation of the enemy,and the precise location of the radiation signal source,which will provide a strong basis for the battlefield dynamic information acquisition.In this paper,a brief introduction to the double satellites interference source location system is presented,and in depth the time-frequency parameters in the location process are studied.This paper first introduces the background and significance of passive location of double satellites,and the status of satellite location at home and abroad,and analyzes the composition,principle and error source of double satellites location system.This paper focuses on the estimation of TDOA and FDOA in double satellites interference source location system,and analyzes the classical Basic Cross Correlation(BCC)method,Generalized Cross Correlation(GCC)method and Cross Ambiguity Function(CAF)method.In order to eliminate the influence of the attenuation factor,the computational accuracy of the BCC method is improved by further simplifying the calculation and combining the properties of the Fast Fourier transform(FFT)to analyze the correlation operation of the discrete signal with finite time length.Based on the conclusion of the BCC,the processing of GCC is further analyzed.The principle of TDOA / FDOA joint estimation and segmented coherent summation of CAF is introduced.The CAF process of discrete signal in finite time length is divided into frequency-compensated cross-correlation method and mixed product Fourier transform method,and compared the two methods.At the same time,this paper proposes combination with the FFT pruning method to achieve the input and output directly cut,we can complete any bandwidth,and any number of frequency output,improve the frequency resolution and to ensure thecomplexity of the operation,making the CAF is more accurate.Based on the characteristics of frequency-compensation of CAF,combined with Continuous Wavelet transform and Correlation Coefficient method,in this paper,cross ambiguity function method based on continuous wavelet transform and a TDOA estimation method based on the cross ambiguity function and comparison of waveform similarity are proposed.In the actual double satellites interference source location system,it is generally impossible to capture multiple times of signal.For the only capture information,proposed the characteristics of multi-scale transform and noise reduction in continuous wavelet transform.Combining the excellent characteristics of the CAF,TDOA / FDOA is estimated at different scales,and the estimation results are clustered to obtain relatively accurate results.In the actual signal processing,when the noise bandwidth is larger than the signal bandwidth,the correlation coefficient effectively reduces the equivalent SNR,the real or imaginary part of the complex signal retains the intermediate frequency in the correlation operation,and the characteristics of the information and the clustering analysis of the time domain search range and the intercepting offset for the weakening of the correlation result with the intermediate frequency are combined to effectively estimate the TDOA Based on the CAF and Comparison of Waveform Similarity.Finally,the paper summarizes the work of this paper,and puts forward any problems and possible solutions,and further prospects for further research.