HF Radar Signal Processing Based On Tomography Imaging And Compressed Sensing

This paper presents the application of a tomography imaging technique to theproblem of high quality target scene reconstruction in spotlight-mode syntheticaperture radar(SAR) system. Based on this, in order to improve the spatialresolution of target detection and recognition in high frequency(HF) radar system,this paper applies tomography imaging concept to HF radar system. Furthermore,the feasibility of this technology applied in HF radar system is discussed.First of all, the effects of finite aperture on resolution and sampling constraintsare discussed. A convolution back projection(CBP) algorithm has been applied toimage reconstruction. By simulation over circular synthetic aperture radar(CSAR)to reconstruct target reflectivity function, it is verified that tomography imagingalgorithm can improve target recognition performance of HF radar effectively.Secondly, based on the range limitation of aspect angle with only oneradar-carrying platform, the approach of multi-aspect observations is applied toimprove the azimuth resolution. Use two-aspect observations as an example, thewave number domain derivation process of target scene reconstruction in highfrequency radar system is described. On the basis of spatial spectrum acquired fromone platform observation, it uses polar format algorithm to fuse spatial spectrums oftwo-aspect observations. Computer simulations verify that two-aspect tomographyimaging technique effectively improves the spatial resolution in high frequencyradar system.Finally, higher resolution imaging demands wider bandwidth and larger array,and subsequently requires more data to process. Conversely, it needs small timewindow for stationary targets in high frequency radar system, to avoid blurring andsmearing of images. Thus the application of the traditional imaging algorithm islimited. Compressed sensing(CS) has recently attracted much interest as it canreduce the number of samples without compromising the imaging quality. Onaccount of this promise, this paper presents a two dimensional imaging algorithmbased on CS. Furthermore, it discusses the applicability of CS and presents theapplication constraint for HF radar system.