Research On Related Technologies Of External Radiation Source Radar

The passive radar is a dual/multi-base radar system that uses a non-cooperative electromagnetic signal transmitted by a third-party to achieve target detection.The radar system does not transmit signals by itself.The system has the advantage of long detection range,great anti-stealth and great survivability,therefore it is become the focus of research.But target echoes are susceptible to other signals,target detection still has difficulty.Aiming at the problems of passive target detection,this paper studies interference suppression,signal extraction and parameter estimation.The main work of this paper is as follows:(1)Research on interference suppression technology.Based on the study of SVSLMS adaptive filtering algorithm,adjusting the step size according to the correlation between the signal after interference suppression and the direct wave.Simulation analysis shows that the improved SVSLMS algorithm has better interference suppression performancehe.At the same time,aiming at the problem that the reference matrix of ECA-B algorithm is too large,the OMP algorithm is used to simplify the reference matrix and effectively reduce the algorithm complexity.(2)Blind source separation technology for signal extraction.The second order blind source separation technique based on joint diagonalization is used to extract the target echo.Taking advantage of the strong correlation of direct wave,Schmidt orthogonalization is adopted to reduce the extracted target echo and the cascading CCA algorithm to the reduced signal,so as to further expand the signal set of two delay to be the signal set of multiple delay and improve the extraction effect of direct wave.(3)The target detection technology of passive radar.On the basis of analyzing the radar model of multi-base external radiation source,aiming at the problem of target detection under the condition of residual direct wave after interference suppression,the GLRT detector using the EM iterative algorithm in the two cases where the noise power is known or unknown is established.The target signal parameters are estimated separately to achieve the detection of the target signal.Compared with the energy detector and the generalized canonical correlation detector,the target detection can be better realized.