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981.
982.
Maneuvering target tracking using extended Kalman filter 总被引:1,自引:0,他引:1
Cortina E. Otero D. D'Attellis C.E. 《IEEE transactions on aerospace and electronic systems》1991,27(1):155-158
A numerically well-conditioned, quasi-extended Kalman filter is proposed. The filter is numerically described. The simulation results presented show that the estimation performance of the quasi-extended filter is superior, for short distances, compared with the widely used linear tracking filters. In addition, the simplicity of the quasi-extended filter makes it very easy to implement 相似文献
983.
Fontana R.J. Richley E.A. Beard L.C. Barney J. 《Aerospace and Electronic Systems Magazine, IEEE》2004,19(5):36-41
Under Phase I of the Defense Advanced Research Projects Agency (DARPA) Networking in Extreme Environments (NETEX) initiative, Multispectral Solutions, Inc. (MSSI) was tasked with the development of a general-purpose, ultrawideband hardware simulator capable of reproducing a wide variety of ultrawideband (UWB) waveforms. The simulator, with UWB outputs from baseband through millimeter wave, was to be used for the purpose of electromagnetic susceptibility testing of legacy military radio, radar, and positioning systems. The ultimate goal of this portion of the Phase I program was the quantitative determination of those UWB parameters (e.g., frequency, power, pulse rate, pulse shape, dithering, etc.) which had the least impact on the operational performance of legacy designs. This describes the development of the MSSI NETEX UWB simulator (BFP1000). 相似文献
984.
C. Fröhlich 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(5):139-145
The methods used to determine the aerosol optical depth as a function of wavelength are briefly described and discussed. Some results from the operational network of the World Meteorological Organization and other, more research oriented studies, are reviewed and critically analysed to assess the reliability and accuracy of such determinations and their value as ground truth measurements for space applications. 相似文献
985.
Robust autofocus algorithm for ISAR imaging of moving targets 总被引:1,自引:0,他引:1
Jian Li Renbaio Wu Chen V.C. 《IEEE transactions on aerospace and electronic systems》2001,37(3):1056-1069
A robust autofocus approach, referred to as AUTOCLEAN (AUTOfocus via CLEAN), is proposed for the motion compensation in ISAR (inverse synthetic aperture radar) imaging of moving targets. It is a parametric algorithm based on a very flexible data model which takes into account arbitrary range migration and arbitrary phase errors across the synthetic aperture that may be induced by unwanted radial motion of the target as well as propagation or system instability. AUTOCLEAN can be classified as a multiple scatterer algorithm (MSA), but it differs considerably from other existing MSAs in several aspects: (1) Dominant scatterers are selected automatically in the 2D image domain; (2) scatterers may not be well isolated or very dominant; (3) phase and RCS information from each selected scatterer are combined in an optimal way; (4) the troublesome phase unwrapping step is avoided. AUTOCLEAN is computationally efficient and involves only a sequence of FFTs. Another good feature associated with AUTOCLEAN is that its performance can be progressively improved by assuming a larger number of dominant scatterers for the target. Numerical and experimental results have shown that AUTOCLEAN is a very robust autofocus tool for ISAR imaging 相似文献
986.
987.
988.
E.M. Wescott H.C. Stenbaek-Nielsen T.J. Hallinan C.S. Deehr J.V. Olson J.G. Roederer R.D. Sydora 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):325-328
On 16 March 1980 a rocket launched from Poker Flat, Alaska, carried a new type of high-explosive barium shaped charge to 571 km, where detonation injected a thin disk of barium vapor with high velocity nearly perpendicular to the magnetic field. The purpose of the experiment, named “King Crab,” was to advance knowledge of the instabilities, waves, and optical and magnetic effects produced. The TV images of the injection are spectacular, revealing three major regimes of expanding material which showed early instabilities in the neutral gas. The most unusual effect of the injection is a peculiar rayed barium-ion structure lying in the injection plane and centered on a 5 km “black hole” surrounding the injection point. Preliminary computer simulations show a similar rayed structure development due to an electrostatic instability. 相似文献
989.
Keith O. Mason France A. Córdova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(9):109-117
Observations with the imaging X-ray detectors on the Einstein Observatory have led to a large increase in the number of low luminosity X-ray sources known to be associated with cataclysmic variable stars (CVs). The high sensitivity of the Einstein instrumentation has permitted study of their short timescale variability and spectra. The data are adding significantly to our knowledge of the accretion process in cataclysmic variables and forcing some revision in our ideas concerning the origin of the optical variability in these stars. 相似文献
990.
W.A. Delamere C.A. Hendrikson D.E. Schneible 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(4):39-47
Requirements on image stability are increasing, often at the same time that instrument external disturbances are increasing. Pointing large diameter optics from the shuttle bay is the prime current example of this situation. In order to achieve cost-effective advanced pointing systems in the face of these problems, a system approach must be taken that encompasses a realistic assessment of requirements, the best possible detector technology, and a broad look at space vehicles and pointing systems that are available. As an example, a rocket instrument for making measurements of the interstellar gas uses a standard pointing system to achieve a spectral resolution of 2 × 105. 相似文献