Research On Short Wave Multi Station Power Synthesis Based On Time Reversal Mirror

When the signal propagates through the short wave channel,the transmitted signal reaches the receiving end through different ways.The received signal is composed of multipath signals with different time delays and Doppler frequencies.If these multipath signals can be coherently superimposed,the received signal power will be improved.Therefore,time reversal technology is introduced to make the multipath signal generated by the transmitter signal through the short wave channel reach the receiver at the same time through the signal "first in and then out",so as to realize energy focusing,so as to improve the power of the received signal.According to the basic principle of time reversal mirror and the propagation environment of short wave channel,this paper studies the application of time reversal mirror technology in multi station power synthesis.The main research work of this paper is divided into three parts.Firstly,the preconditions for the application of time reversal mirror and the feasibility of its application in short wave channel are studied.In view of whether the time reversal mirror technology can be applied to the short wave channel,through the theoretical derivation of the time reversal technology and the processing of the transmission data of the actual short wave channel,it is concluded that the short wave channel has short-time invariance and reciprocity,which verifies the feasibility of the application of the time reversal mirror in the short wave channel and lays a foundation for future research.Secondly,the influence of single station processing based on time reversal mirror on the received signal power is studied.Firstly,according to the change of received signal power caused by different kinds of signals using time reversal processing in the case of single channel,theoretical derivation and simulation verification are carried out,and the conclusion that time reversal processing can not improve the received signal power under the condition of single channel propagation is put forward.Then the array received signal is transmitted after time reversal processing,and the received signal power obtained by direct transmission without any processing is compared.Through formula derivation and simulation result analysis,it is concluded that the time reversal mirror can obtain higher power than direct reception and forwarding when the array received and transmitted signals are used.Finally,aiming at the influencing factors in the process of time reversal processing,the simulation is used to illustrate the relationship between each factor and the received signal power,so that these factors can be changed in practical application to improve the received signal power.Finally,the problem of multi station power synthesis based on time reversal mirror is studied.Aiming at the function of time reversal mirror in multi station power synthesis,through the simulation of the received signal after time reversal processing under the condition of multi station,it is verified that the time reversal mirror can further reflect the advantages of its energy focusing characteristics in the more complex communication environment of multi station,and can obtain higher signal power gain compared with single station processing.Moreover,aiming at the problem that the effect of the array decreases due to the similar incidence angle of the multi-path,through the analysis of the received signal obtained after the time reversal processing in the case of similar angles,it is concluded that the time reversal mirror can improve the correlation between the processed signal and the original signal even if it can not improve the power of the received signal,which puts forward a new idea for the multisource coherence technology.Finally,aiming at the problem of time synchronization error in multi station time reversal processing,through the analysis of simulation results,it is concluded that the larger the time synchronization error between stations,the worse the gain effect of signal power.