RCS Dynamic Measurement And Data Processing Of Target

Imaging radar, which can provide an all-weather day/night capability to generate a high-resolution representation of radar reflectivity of targets over a long range, has received intensive attention because of its potential applications in both civilian and military applications. In order to obtain high-resolution radar images, it is necessary to maintain the precise phase relationship between return signals. This requires precise motion compensation, because the unplanned perturbations of the relative motion between the radar and the scatters causes phase errors, which may destroy the phase coherent of return signals and then blur the image.The study on the raw radar data shows that the traditional algorithms of motion compensation and imaging to ISAR available cannot suit to high-speed maneuvering targets. In this paper some algorithms of motion compensation and imaging to high-speed maneuvering targets are proposed and verified by raw and simulation data.The main contributions of the dissertation are as following:A new algorithm for relative motion compensate is proposed. Because conventional motion compensation methods assume that targets' positions are almost fixed during the imaging time, which requires the targets be rigid. It is not easy for us to obtain good result for several relative motion targets using these methods. In this chapter the model of relative motion targets is established, and a new algorithm for relative motion compensation based on Keystone transformation and auto-clean algorithm is proposed. The imaging results based on simulation and real data validate the new relative motion compensation method.A new algorithm for spinning motion compensation is presented. ISAR imaging of a self-spinning motion target is described, and the effect of self-spinning motion for ISAR image is analyzed, the Doppler-frequency expression produced by self-spinning motion is deducted. Using multi-component linear frequency-modulated signals decomposition method based on "CLEAN" in frequency domain and AJTF to estimate parameter of echo's phase, we can remove the influence of high step phase produced by spin and attain clarity ISAR images of self-spinning targets.Using the improved time-frequency distribution series (TFDS) to improve Imaging resolution. The TFDS has been tested effectively in the balance of the cross-term suppression and the time-frequency resolution. We replace the complex form discrete Gabor transform with the real one to reduce computing. On the other hand, we get ride of the redundant computing about the time-frequency atom. The simulation of the multi-component non-station signal shows that the improvement of the TFDS method accelerates the computing.Exploiting the data processing software to realize RCS dynamic measure of high-speed maneuvering targets. In this chapter, using the data port of the narrowband radar system available, we have designed a sort of I/Q demodulator to alter the data sampling system. Based on received signals of narrow band single pulse radar and its orbit data, using forenamed algorithms, we exploit the data processing software, which realizes range compression and relative motion compensation and cross-rang imaging of high-speed maneuvering targets.Based on forenamed works of the dissertation, the whole process can display imaging results and RCS dynamic measure of high-speed maneuvering targets is achieved. ISAR imaging results of experiments are consistent with optical radar images.