Research On Detection And Recognition Algorithm Of Low Intercept Probability Radar Signal

Electronic reconnaissance is not only an important guarantee to win the victory of modern electronic warfare,but also an important symbol of national military strength.Now China's neighboring countries and regions are accelerating the assembly of low probability of interception(LPI)radar weapon system,leading to China's battlefield electromagnetic environment becoming more and more complex.In view of the current situation,the existing electronic warfare reconnaissance system has been very difficult to deal with the threat posed by LPI radar,manifested in: the current complex electromagnetic environment and LPI radar power management technology,resulting in existing reconnaissance equipment for weak signal interception difficult;LPI radar uses a complex waveform design,resulting in the current reconnaissance aircraft is difficult to identify the type of signal modulation;It is hard to achieve the LPI signal processing engineering.In order to solve the problemthat the existing electronic reconnaissance system theory and technology can't meet the threat of perceived demand for battlefield electromagnetic environment,this paper explored the detection and recognition of LPI radiation source in complex electromagnetic environment.Based on the analysis of the LPI radar waveform characteristics,this paper designs the LPI signal generation software to simulate the typical LPI signal based on MATLAB,and proposes a LPI signal joint detection algorithm which under the strong background noise;improved a feature extraction algorithm and classifier to realize the classification and recognition of typical LPI signals;and designed a signal recognition system based on DSP(TMS320C6678).The specific research contents are as follows:Firstly,the paper analyzes the characteristics of LPI radar signal by using ambiguity function as analysis tool,discussing its low intercept performance,and designs LPI radar signal generation software based on MATLAB graphical interface.This software is used to generate common LPI radar Signal,The signals generated by this software and the time-frequency images can be input as algorithms for subsequent chapters.Secondly,this paper has proposed a combined detection method of LPI signal under low SNR condition This paper propose a radial integral transformation of the ambiguity function of the signal to obtain the peak of the energy integral for the interception of the important monitoring band and the signal density,and propose an improved top-hat transformation based on the morphological processing to suppress the foundation caused by the noise.In this way,this paper improve the algorithm at low signal to noise ratio of adaptability.In the case of large interception of signal density,the detection performance is improved by non-conjunction accumulation.A periodic radial integral transform detection algorithm is designed to make full use of the periodic component of the signal to accumulate energy.The proposed algorithm reduces the computational complexity of the current LPI detection algorithm and improves the processing capability under the premise of ensuring the detection capability of the weak signal,and puts forward the feasible idea for the practical engineering application.Thirdly,a method of signal modulation type recognition is improved.The time-frequency image is preprocessed by the modulation energy automatic interception algorithm based on the marginal frequency distribution to reduce the redundant information of the image and the interference of the noise.,and then the dynamic threshold de-noising is further remove noise interference.The information of the time-frequency diagram of the pre-processed time is extracted by using the improved LPQ(Local Phase Quantization)operator eigenvector extraction method.Through the improved BPR classifier to carry out the interception of the signal LPI modulation type recognition,in the low signal to noise ratio of the recognition results were accurately output.Lastly,the hardware architecture of signal recognition system based on parallel multi-core DSP TMS320C6678 processor is proposed.This paper designed a multi-DSP parallel processing architecture and the basic process of radar signal identification.The TMS320C6678 multi-core parallel scheduling scheme under the mixed model is proposed.,and divided the task of DSP processing according to the actual reconnaissance environment.This paper alsodesigned the detail of data sharing mode and verified by practical engineering.