Blind Detection And Parameter Estimation Of Low Probability Of Intercept Signals

Low probability of intercept signal is often used in radar and communication systems, because of its low power, wide bandwidth and strong anti-jamming capability and low probability of intercept characteristics in the complex electromagnetic environment,. The conventional receiver is difficult to realize blind detection and parameter estimation of LPI signal. Signal detection and parameter estimation is the foundation of the communication confrontation, therefore, a set of analysis for Communication reconnaissance has a great scientific significance and application value.First for the blind detection and parameter estimation of conventional DS signal,we use the energy detection method to detect the exitence of the signal; According to the estimation of carrier frequency, the thesis use the frequency doubling method, auto correlative accumulation frequency doubling method, cyclic spectrum analysis and time-frequency analysis method, and according to the frequency doubling method gives multiple autocorrelation frequency doubling method. Then through a large number of simulation experiments, comparative analysis of all algorithms. Comprehensive variety of performance of the proposed carrier frequency is estimated using the multiple autocorrelation multiplier method. The delay and multiply method and it’s improved one,also time-frequency analysis jointing method is used to complete spreading code rate estimates taking advantage of the correlation features of spreading code. Taking advantage of the different correlation features of pseudo-random code sequence and the noise, the time domain autocorrelation method is emphasized to complete the period estimation algorithm of spresding code.Secondly aming at the blind detection and parameter estimation of a new generation of BOC modulated signal. For BOC modulation signal blind detection, making use of the unmached multi-peak features of correlation function of BOC modulation signal, the thesis present an orthogonal shunt side peak equal space detection method, to achieve the effective detection of BOC modulated signal.For the difficulty of carrier frequency estimation,square wave sub carrier rate and spread spectrum code rate estimation which brought by the multi autocorrelation peak and separation power spectrum characteristics of BOC modulated signal,using the square frequency method to achieve the efficient estimation of carrier frequency.The two correlation peaks joint estimation method is proposed,using the self correlation peak and the number of crossing zero point and correlation peaks between adjacent side peaks, can effectively estimate the square wave subcarrier rate and rate of pseudo-random code.Thirdly aming at the parameters extraction of the LPI radar multi phase modulation signal, mainly on the-Radon transform algorithm of Wigner-Ville distribution and QMFB parameter extraction algorithm, through a large number of simulation experient erified the performance of various algorithms and compare the performance of each algorithms.Finally design the whole blind detection and parameter estimation system of LPI,and gives the design of each module of the system.