The approach for enlargement of SAR patch mapping area by antenna beam scan is investigated, which serves for moderate fine-resolution mapping of medium-sized terrain patches. The scanning angular velocity and the sca...The approach for enlargement of SAR patch mapping area by antenna beam scan is investigated, which serves for moderate fine-resolution mapping of medium-sized terrain patches. The scanning angular velocity and the scanning angular scope are determined respectively. The angular velocity of the scanning antenna is controlled to scan over just one azimuth 3 dB beam width in the time interval during which the radar platform moves over one synthetic aperture length determined from the desired cross-range resolution, radar wavelength, nominal slant range, and squint angle. The scanning angular scope is mainly determined by the azimuth width of the terrain patch, nominal slant range, squint angle, platform velocity, and azimuth beam width. Finally, the related experimental results of an airborne SAR are presented. The linear range-Doppler algorithm is employed in image formation after motion compensation is conducted to remove the effect of transnational motion of the radar platform relative to the map center.展开更多
In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm ca...In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm can successfully achieve to design DOEs for beam shaping. Compared with conventional algorithm, this algorithm can provide faster convergence, more powerful ability to overcome local minimum problem and better shaping quality. By computer simulation, the result has shown that the DOEs designed by this algorithm has snch advantages as high uniformity at the main lobe, low profile error and steep edge.展开更多
An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set （POCS） theory. Due to the fact that the DCT characteri...An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set （POCS） theory. Due to the fact that the DCT characteristics of shifted blocks are different caused by the blocking artifacts, a novel smoothness constraint set and the corresponding projection operator were proposed to reduce the blocking artifacts by discarding the undesired high frequency coefficients in the shifted DCT blocks. The experimental resuhs show that the propo,sed algorithm outperforms the conventional algorithms in terms of objective quality, subiective quality, and convergence property.展开更多
This letter investigates an efficient design procedure integrating the Genetic Algorithm (GA) with the Finite Difference Time Domain (FDTD) for the fast optimal design of Smart Antenna Arrays (SAA). The FDTD is used t...This letter investigates an efficient design procedure integrating the Genetic Algorithm (GA) with the Finite Difference Time Domain (FDTD) for the fast optimal design of Smart Antenna Arrays (SAA). The FDTD is used to analyze SAA with mutual coupling. Then,on the basis of the Maximal Signal to Noise Ratio (MSNR) criteria, the GA is applied to the optimization of weighting elements and structure of SAA. Finally, the effectiveness of the analysis is evaluated by experimental antenna arrays.展开更多
文摘The approach for enlargement of SAR patch mapping area by antenna beam scan is investigated, which serves for moderate fine-resolution mapping of medium-sized terrain patches. The scanning angular velocity and the scanning angular scope are determined respectively. The angular velocity of the scanning antenna is controlled to scan over just one azimuth 3 dB beam width in the time interval during which the radar platform moves over one synthetic aperture length determined from the desired cross-range resolution, radar wavelength, nominal slant range, and squint angle. The scanning angular scope is mainly determined by the azimuth width of the terrain patch, nominal slant range, squint angle, platform velocity, and azimuth beam width. Finally, the related experimental results of an airborne SAR are presented. The linear range-Doppler algorithm is employed in image formation after motion compensation is conducted to remove the effect of transnational motion of the radar platform relative to the map center.
文摘In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm can successfully achieve to design DOEs for beam shaping. Compared with conventional algorithm, this algorithm can provide faster convergence, more powerful ability to overcome local minimum problem and better shaping quality. By computer simulation, the result has shown that the DOEs designed by this algorithm has snch advantages as high uniformity at the main lobe, low profile error and steep edge.
文摘An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set （POCS） theory. Due to the fact that the DCT characteristics of shifted blocks are different caused by the blocking artifacts, a novel smoothness constraint set and the corresponding projection operator were proposed to reduce the blocking artifacts by discarding the undesired high frequency coefficients in the shifted DCT blocks. The experimental resuhs show that the propo,sed algorithm outperforms the conventional algorithms in terms of objective quality, subiective quality, and convergence property.
文摘This letter investigates an efficient design procedure integrating the Genetic Algorithm (GA) with the Finite Difference Time Domain (FDTD) for the fast optimal design of Smart Antenna Arrays (SAA). The FDTD is used to analyze SAA with mutual coupling. Then,on the basis of the Maximal Signal to Noise Ratio (MSNR) criteria, the GA is applied to the optimization of weighting elements and structure of SAA. Finally, the effectiveness of the analysis is evaluated by experimental antenna arrays.
