Translational motion compensation of ballistic target based on radon transform
Ballistic target translational motion compensation is beneficial to motion parameter extraction. Aiming at the problem of multiple scattering points translational motion compensation, an algorithm is proposed to extract the translational motion parameters of ballistic targets based on using the projection transform of the whole micro-frequency curve by Radon transform in this paper. First, establishing and analyzing the typical ballistic target model and the expressions of scattering points' micro-frequency are solved. Second, target signal is pre-compensated based on radar information and time-frequency transform. And Radon transform is applied to the parameter projection of time-frequency curve. Then translational motion parameters are estimated based on minimum entropy criteria and gauss fitting. Finally, translational motion is compensated by making use of the estimated motion parameters. Simulation results verify the validity of the proposed algorithm.
Translational Motion Compensation of Space Micromotion Targets Using Regression Network
The high-speed translational motion of space targets will cause the micro-Doppler to shift, tilt, and fold, which brings great difficulty to the extraction of micromotion features. Translational motion must be compensated in advance to extract the authentic characteristics of micro-Doppler curves. To solve the problem of translational motion compensation, an estimation method of translational parameters based on deep learning theory is proposed. A polynomial model describing translational motion is constructed firstly by analyzing its dynamic principle. Meanwhile, the parametric characterization of micromotion signal is deduced by taking the cone target as an example. On this basis, two regression networks that can estimate acceleration and velocity respectively from the time-frequency graph are built using transfer learning. The translational motion compensation is accomplished with high accuracy and low computation complexity. The proposed method can also achieve satisfactory results in the presence of high intensity noise and discontinuous scattering points. Finally, the effectiveness and robustness of the proposed method are validated by simulations.
AMERICAN WESTS: PREFACE TO A GEOGRAPHICAL INTERPRETATION
ABSTRACT Geographers might make a very significant contribution to the interpretation of the American West and of the American nation by a systematic investigation of the West as a set of dynamic regions. The outline offered suggests a focus upon four categories of regional features (population, circulation, political areas, and culture) to be examined as complexes changing through four recognizable stages (nuclear, regional, regional-national, metropolitan-national) from initial European colonization to the present with projections into the future.