Reconnaissance And Processing Of Signals With Phase-frequency Hybrid Modulation

Technology for analyzing signal modulation is the basis of reconnaissance and processing of electronic intelligence.In order to achieve low probability of detection and high resolution,the technology of phase-frequency hybrid modulation represented by PSK+FSK has been widely used in modern radar and communication systems.Its low performance of intercept and complex rules of parameter bring many challenges to the acquisition of non-cooperative information.This dissertation studies the technology of signal modulation analyzing for the urgent of reconnaissance and processing of signals with phase-frequency hybrid modulation.The primary content of this dissertation is as follows:(1)The model and transmission characteristics of a special phase-frequency hybrid modulation signal are studied.Two types of commonly used phase-frequency hybrid modulation are discussed,and their defects of transmission performance are analyzed;The improved model of modulation based on the commonly used phase-frequency hybrid modulation model——FSK/BPSK-VSB model,is studied;The transmission characteristics of the BPSK-VSB model are analyzed and the advantage of modulation of integration of radar and communication of FSK/BPSK-VSB is discussed by the simulation of transmission performance under the nonlinear amplifier.(2)The estimation of the position of the frequency hopping point of the FSK/BPSK-VSB modulated signal is studied.Three commonly used estimation methods of the position of frequency hopping point are discussed,and their defects of estimation of the frequency hopping point of FSK/BPSK-VSB modulated signal is analyzed.Combining the phase change law of FSK/BPSK-VSB modulated signals,an estimation algorithm of the frequency hopping point position based on the difference of carrier frequency baseline(the base component of the instantaneous frequency of FSK/BPSK-VSB modulated signals)is proposed.The performance of the algorithm for detection and position estimating of the frequency hopping point of FSK/BPSK-VSB modulated signals is tested by simulation.(3)The modulation recognition of BPSK-VSB modulated signals is studied.A modulation recognition algorithm based on multiple parameters is proposed and three modulation characteristics of BPSK-VSB modulated signals are extracted,including relative error of code width,the number of times the square spectrum has passed the threshold,and spectrum asymmetry.Then the KNN classifier is used to perform binary decision and classification on the modulation characteristics of 7 kinds of modulated signals by utilizing binary tree.Simulation results indicate that the proposed algorithm can effectively identify this BPSK-VSB modulated signal and has a low false negative rate for other modulation type signals.(4)Design and implement a modulation analysis software for hybrid modulated signals for the requirement of reconnaissance and processing of signals with FSK/BPSK-VSB modulation.Automatic processing of multiple hybrid modulated signals including FSK/BPSK-VSB modulation is realized in modulation recognition,sub-pulse cutting and parameter stimation,and the validity of the proposed modulation recognition method and sub-pules cutting method for phase-frequency hybrid modulated signals is verified.