Research On Time Reversal And Engineering Application

In order to solve the problem of multipath interference in the process of time reversal technology,the high probability of target detection is achieved by using abundant scattering in the multipath environment.Time reversal is applied to practical engineering and its time domain model expression is derived.In the DOA estimation of detection probability and target,the performance of the added time reversal technology is better than that of the traditional method.Time reversal technology originated from the generalization of phase conjugation mirrors in the field of optics.It is applied to the field of electromagnetic fields.It combines the basic principles of electromagnetic wave transmission and array signal processing techniques,and has the characteristics of space-time focusing in complex multipath scattering environments.Adaptively focusing at the target position and reconstructing in the form of an inversion wave can obtain a much larger resolution than the usual array aperture,which greatly improves the resolution of the radar system.This paper focuses on the time inversion algorithm and its application in different scenarios.Firstly,the basic principle of time inversion technology is analyzed.The time inversion technique is applied in the multipath suppression method.Establish a basic mirror reflection multi-path transmission model,analyze the principle of multi-path problems and the harm to the target detection.In the actual radar system,the traditional multi-path suppression method requires higher technical requirements,and thus proposes to apply the time inversion technique to the problem of multi-path suppression.Then,the design time is used to invert the operation flow of the multipath suppression method,and a typical linear frequency modulation(LFM)pulse signal is used as the initial transmission signal to analyze the feasibility and effectiveness of the time inversion technology application from a theoretical perspective.Simulation experiments were conducted to compare and analyze the effect of time-inversion techniques on the detection performance of targets under different SNR conditions.Finally,Chirp modulation combining with block-based time reversal mobile communication method is proposed.The pulse compression characteristic and the Doppler shift tolerance of Chirp signal are deduced in theory.Then the basic principle of Chirp modulation and demodulation technology is described.The system of block-based time reversal combining with Chirp modulation mobile underwater acoustic communication method and data frame structure are designed.Then through theoretical derivation and simulation research,the scheme of compensating the Doppler extension is given.the scheme of setting the length of the block data according to the coherence time of channel is proposed.Finally,the communication method is simulated under two-kilometer stationary and mobile communication environment.The simulation results show that the proposed method has good performance.