Research on Parameter Estimation Technologies of Distributed SAR Moving Targets
|School||Harbin Institute of Technology|
|Course||Information and Communication Engineering|
|Keywords||Parameter estimation Multiple Moving Targets Space - time-frequency algorithm Fractional Fourier Transform|
Spaceborne synthetic aperture radar system because there is a strong concealment, the distant detection range advantages, greatly improved distributed synthetic aperture radar system in the military war survival, combat capability, so the parameter estimates used in radar systems The algorithm is increasingly becoming a key part of military technology. Spaceborne the Distributed Synthetic Aperture Radar system as the background, the of multi synthetic aperture radar platform on the the slow straight and high-speed moving target parameters estimation techniques, and research and compare different parameter estimation algorithm. Distributed synthetic aperture radar imaging process, the moving target Doppler center frequency and chirp rate is different from stationary targets, so stationary targets distributed synthetic aperture radar (synthetic aperture radar SAR) image, moving target, not only in azimuth offset to occur, and the image will also be defocusing, resolution will drop If you want to get the azimuth focus of high resolution SAR images of moving targets, moving target re-focus imaging, and therefore an accurate estimate moving target Doppler parameter is the key to accurate imaging of the moving target. Ground moving target in modern warfare, SAR processing is often dense multiple moving targets, there are multiple moving targets at the same time when the SAR synthetic aperture, each target parameters are similar, it is difficult to distinguish and parameter estimation accuracy is not high. This makes the parameters of multiple moving objects within the distributed SAR synthetic aperture is estimated to be a thorny issue, it is necessary to find a suitable match multiple moving objects echo characteristics to accurately estimate the parameters of the moving target. Topics can be summarized as follows: 1) moving target parameter estimation for spaceborne synthetic aperture radar system, when there are multiple moving targets within the SAR synthetic aperture when using traditional parameter estimation method due to its similar tone frequency, difficult to distinguish between the multiple targets, and the estimated accuracy is not high, the paper presents a cascade Hilbert Huang Transform - Wigner method (Hilbert Huang Transform-Wigner Ville Distribution, HHT-on WVD) while addressing the HHT when frequency concentration is not high and the the WVD presence of the cross terms, so as to realize the accurate estimation of the parameters of multiple moving targets in SAR synthetic aperture. Simulation results show that the algorithm can well distinguish between multiple moving targets, and parameter estimation accuracy and computing speed, has good practical value. 2) difficult for spaceborne distributed synthetic aperture radar system ground targets azimuth velocity accurately estimate the traditional time-frequency analysis method, a fractional Fourier transform (Fractional Fourier Transform, FrFT) - multiple signal Classification (Multiple Signal Classification, MUSIC) space-time-frequency methods. First FrFT signal vector and frequency distribution matrix constructed empty; then apply this distribution matrix instead of the covariance matrix in the traditional MUSIC algorithm to obtain the the FrFT-MUSIC empty when the spectrum, the target speed is estimated by searching the spectral function. Simulation results show that the method of multi-target speed estimation accuracy is high, the ability of anti-noise, no blind speed. 3) high-speed moving target parameter estimation problems for a number of synthetic aperture radar platform, the space-time-frequency algorithms suitable for high-speed moving target parameter estimation. Multi-platform, high velocity distance migration issues and their resolution algorithm. In this paper, synthetic aperture radar signal model, the simulation of the entire process to analyze and verify the effectiveness of this algorithm.