Single Channel Asymmetric Mixed Communication Signal Separation And Parameter Estimation

With the rapid development of various technologies in the field of communication,electronic information warfare has become the mainstream in the current digital battlefield.Single-channel receiving equipment has been widely used because of its smaller overall equipment volume,simpler organization and higher concealment in wartime environment.The traditional multi-channel separation algorithm is no longer practical because of the time-frequency aliasing problem of the received single-channel mixed signal.Therefore,in this thesis,the separation problem of single-channel asymmetric mixed communication signals is studied,mainly from the waveform reconstruction and frequency shift filtering of strong component signals with large amplitude.The research content of this thesis is as follows:1.The common communication signals are cyclically stationary signals.Through analyzing the combined characteristics of the cycle frequency of the signals’ secondorder cyclic cumulant,second-order conjugate cyclic cumulant and fourth-order cyclic cumulant,the corresponding estimation algorithm is proposed for the blind estimation of carrier frequency,code rate,modulation style and other parameters of the singlechannel asymmetric mixed communication signals.The feasibility of the algorithm is verified by experimental simulation.At the same time,aiming at the problem of color noise in frequency spectral lines of cyclic cumulants,a method of spectral line smoothing is proposed to suppress color noise and further improve the accuracy of estimation results.2.Aiming at the separation problem of time-frequency aliasing mixed signals with different amplitude-of-two received by single-channel devices,a separation algorithm based on digital cancellation is proposed.Firstly,the parameter estimation algorithm given in the previous point is used to realize parameter estimation and demodulation of strong component signals with large amplitude.Secondly,combined with the demodulated baseband element sequence and signal parameters,the waveform reconstruction of the strong component signal is realized.Finally,LMS and RLS adaptive filters are used to separate the mixed signals by digital cancellation.The feasibility of the algorithm is verified by experimental simulation,and the relationship between the separation effect and the signal-to-noise ratio(SNR),signal-to-stem ratio(SIR)and overlap ratio is analyzed.3.Combined with adaptive frequency shift filter,an algorithm based on blind adaptive frequency shift filter is proposed for the separation of single channel asymmetric mixed communication signals.Firstly,the cycle frequency point of one component signal is obtained by parameter estimation.Secondly,the corresponding cycle frequency shift filter is designed according to the selected cycle frequency.Finally,the feasibility of the algorithm is verified by experimental simulation,and the relationship between the separation effect and the signal-to-noise ratio(SNR),signal-tostem ratio(SIR)and overlap ratio is analyzed.