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排序方式: 共有1519条查询结果,搜索用时 0 毫秒
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Zhuhui Jiang Wei Zhang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(6):1887-1895
This paper researches on Synthetic Aperture Radar (SAR) ocean wind retrieval approach, evaluates the method of Damped Newton VARiational method (DNVAR) and the direct method (DIRECT) using two years’ real SAR data and different background winds. Experiments are carried out using SENTINEL-1 SAR information as observation, National Data Buoy Center (NDBC) buoy data as in-situ data, Global Forecast System (GFS), Advanced SCATterometer (ASCAT), WindSAT, and Cross-Calibrated Multi-Platform (CCMP) wind products as background data. Thousands of match-ups are extracted. Results show that DNVAR can improve the wind field accuracy when the background data is ASCAT and CCMP. Especially, DNVAR wind speed results are much better than the official product of SENTINEL-1 wind data. The background data is crucial to the wind field retrieval results, so high accuracy of background data could lead to high accuracy results. 相似文献
873.
基于星上实时信号处理机的Chirp Scaling算法实现方法 总被引:3,自引:0,他引:3
基于改进的Chirp Scaling算法,提出了一种适用于星上实时信号处理机的高效成像处理实现方法,其核心思想也可应用于其它高分辨率星载SAR的精确成像算法.首先介绍了实时信号处理机的结构,分析了数据处理粒度及其并行流水处理结构.在此基础上,针对单个粒度的成像处理重新设计了算法流程,提出了一种高效的实现方法.利用实时信号处理机,对仿真的回波数据进行了成像处理实验,结果表明:在41?s内能够完成成像处理,成像处理速度和图像质量满足系统设计要求,从而验证了该方法的有效性. 相似文献
874.
Michael Vacek Ivan Prochazka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Spaceborne altimeters are common instruments onboard the deep space rendezvous spacecrafts. They provide range and topographic measurements critical in spacecraft navigation. Simultaneously, the receiver part may be utilized for Earth-to-satellite link, one way time transfer, and precise optical radiometry. The main advantage of single photon counting approach is the ability of processing signals with very low signal-to-noise ratio eliminating the need of large telescopes and high power laser source. Extremely small, rugged and compact microchip lasers can be employed. The major limiting factor, on the other hand, is the acquisition time needed to gather sufficient volume of data in repetitive measurements in order to process and evaluate the data appropriately. Statistical signal processing is adopted to detect signals with average strength much lower than one photon per measurement. A comprehensive simulator design and range signal processing algorithm are presented to identify a mission specific altimeter configuration. Typical mission scenarios (celestial body surface landing and topographical mapping) are simulated and evaluated. The high interest and promising single photon altimeter applications are low-orbit (∼10 km) and low-radial velocity (several m/s) topographical mapping (asteroids, Phobos and Deimos) and landing altimetry (∼10 km) where range evaluation repetition rates of ∼100 Hz and 0.1 m precision may be achieved. Moon landing and asteroid Itokawa topographical mapping scenario simulations are discussed in more detail. 相似文献
875.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(1):163-174
Due to the differences of ionospheric modeling methods and selected tracking stations, the accuracy and consistency of Global Ionospheric Maps (GIMs) released by Ionosphere Associate Analysis Centers (IAACs) are different. In this study, we evaluate and analyze in detail the accuracy and consistency of GIMs final products provided by six IAACs from three different aspects. Firstly, the comparison of these GIMs shows that the mean bias (MEAN) is related to the modeling methods of various IAACs. The variation trend of the standard deviation (STD) is consistent with the solar activities, and accompanied by certain seasonal and annual periodic variations. The MEAN between IGS and each center is about −1.3 to 1.0 TECU, and the STD is about 1.4–2.5 TECU. Secondly, the validation with GPS TEC shows that the STD of CODE is the smallest at various latitudes, and the STD is about 0.7–4.5 TECU. Thirdly, The validation with the Jason2 VTEC shows that the STD between Jason2 and IAACs is about 4.4–5.2 TECU. In addition, the STD between Jason2 and six GIMs in the areas with more tracking stations is better than that of the regions with fewer tracking stations in different latitude regions. Regardless of whether the tracking stations are more or less, the MEAN and STD in high solar activity are larger than in low solar activity. 相似文献
876.
为解决雷达图像仿真中海量地面材质数据的存储和加载问题,采用基于自适应最大行程长度编码和修正 偶对的压缩算法进行材质数据的压缩,从而有效地减少了数据的存储量,消除数据传输的瓶颈,提高了数据传输的 吞吐能力。压缩算法面向 GPU快速处理,得到压缩数据适用于 GPU进行快速解压。 相似文献
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878.
刘兴明 《海军航空工程学院学报》2011,26(6):691-694
为了减少反舰导弹受冲淡干扰的几率,要求末制导雷达在保证捕捉概率的同时尽量减小角度搜索范围。为此,提出了末制导雷达捕捉目标所需最小角度搜索范围模型,推导了最小角度搜索范围表达式及其对应的最佳开机距离表达式。在不同的探测距离下,以高亚声速反舰导弹为例进行了仿真计算。结果表明,最小角度搜索范围在+30°之内,小于某些反舰导弹... 相似文献
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