Research On In-pulse Modulation Recognition Technology Of Radar Signal Based On Time-frequency Analysis

With the rapid development of modern electronic and radar technology,the electromagnetic signal is becoming more and more intensive,and the signal density of electromagnetic threat environment can reach a million levels,at the same time new radar system has emerged and occupied a domain position gradually.The recognition of radar signals based on the conventional parameters has been unable to satisfy the increasing complex electromagnetic signal environment,so it is essential to study the characteristics of the intra-pulse parameters intensively to meet the needs of modern electronic warfare environment.The analysis of intra-pulse feature is a new technology that began to be researched in the mid-1980s.In the 1990s,foreign countries have been equipped with advanced subtle feature extraction and analysis equipment,which has enhanced the electronic warfare capabilities of foreign troops.In this technology,the method of extracting features from the pulse has always been an important subject for scientific research and engineering personnel.After unremitting efforts,some effective methods have been explored and many mature estimation algorithms and related technologies have been formed.The main research content of this article is as follows:1.Introduced the mathematical model of the radar radiation source signal,gave a concrete implementation form of several simulated radar radiation source signals,simulated the time domain waveform and the frequency domain waveform.2.The time-domain method of intra-pulse feature analysis of radar signals was studied.The principle of instantaneous autocorrelation method is analyzed.The performance evaluation of the method is obtained through simulation analysis.The phase ambiguity existing in the instantaneous autocorrelation method is improved,the phase unambiguity range is extended to 4 times,the extraction efficiency of signal instantaneous frequency is also improved.3.The time-frequency domain method for the analysis of in-pulse features of radar signals was studied.To meet the requirement of higher recognition accuracy under low signal-to-noise ratio,an integrated method for in-pulse feature analysis based on Short-time Fourier transform combined with GRNN,PNN neural network and hierarchical self-coding model is proposed.This method can obtain better recognition performance when the number of training samples is small,and increasing the number of training samples appropriately is helpful for parameter learning and tuning of neural network and hierarchical automatic encoder models.