Analysis And Evaluation Of Complex Electromagnetic Environment Based On Time-frequency Generalized S-Transform And VL-MOBP Neural Network

Complex electromagnetic environment refers to the sum of all electromagnetic phenomena in a certain space-time and frequency range,in which various electromagnetic signals are dense and crowded,the intensity changes dynamically overlap,the confrontation features are prominent,and the influence on electronic information system,information equipment and information efficiency is exerted.With the continuous progress and development of modern communication technology,electromagnetic signals are increasingly dense,and available spectrum resources are becoming less and less.The thermal effect and the strong electric field effect caused by the electromagnetic interference can make the information electronic equipment produce the wrong action,the electronic equipment part function failure,serious may cause the malignant accident.Therefore,how to effectively protect the electromagnetic interference and correctly evaluate the complexity of the electromagnetic environment in which electronic information equipment is located has become the focus of extensive attention of scholars at home and abroad.Firstly,this paper analyzes the basic characteristics of battlefield electromagnetic environment signals,and discusses the time-frequency analysis methods such as Short Time Fourier Transform(STFT),Wavelet Transform(WT)and S-transform.Abstract:Aiming at the problem that the time-resolution and frequency resolution cannot be taken into account in the signal analysis of complex electromagnetic environment by S-transform method,a time-frequency occupancy parameter extraction method of time-frequency generalized S-transform was proposed,which could take into account both time-resolution and frequency resolution.The interference communication signals of electronic equipment in complex electromagnetic environment are analyzed twice in the case of ?>1,?>1,namely high time resolution and ?<1,?<1,namely high frequency resolution,and the time domain occupancy and frequency domain occupancy of the interference signals are extracted respectively.Then,the signal is transformed by time-frequency generalized S transform to extract the energy occupation of the interference signal.Finally,the evaluation index is formed by combining the intensity of electromagnetic background noise.Secondly,aiming at the qualitative and quantitative grading problem of complex electromagnetic environment assessment,a Variable Learning Rate Momentum Backpropagation(VL-MOBP)neural network assessment method for complex electromagnetic environment was proposed.The problems of Probabilistic Neural Network(PNN)and Deep Convolutional Neural Network(DCNN)model construction and long training time were solved.The four evaluation indexes used for complexity evaluation of interference signals are fed into the trained VL-MOBP neural network.According to the network output,the quantitative and qualitative analysis of interference signals is carried out according to the complexity grading standard proposed in this paper.Finally,the experimental method of complex electromagnetic environment assessment is studied.The hardware experiment platform is built by using arbitrary waveform generator,spectrum analyzer,transceiver antenna and integrated time-frequency generalized S-transform Lab VIEW test system.An arbitrary waveform generator is used to generate deceptive electromagnetic interference signals containing 10dB Gaussian noise at the same frequency to conduct electromagnetic radiation interference on RFID communication signals.The changes of IQ and bit error rate of RFID communication signals after interference are observed.The complexity of the interference signal is verified by calculating the aggregation degree of the IQ complex signal of the disturbed communication signal,and the proposed method is compared with other methods for the complexity assessment of electromagnetic environment under the same environment.The experimental results show that the complexity level of the interference signal obtained according to the aggregation degree of the IQ complex signal of the disturbed communication signal is consistent with the complexity level of the evaluation method proposed in this paper,and the electromagnetic environment complexity evaluation method proposed in this paper has higher accuracy compared with other evaluation methods.The experimental results show that the proposed method is correct and effective in the complexity assessment of electromagnetic environment.