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71.
海洋监视卫星无源被动定位精度分析 总被引:7,自引:0,他引:7
分析了利用三星编队卫星对海上目标进行无源侦察、监视的原理,建立了利用时差定位法进行定位的精度模型,在此基础上推导了卫星对目标的定位精度与卫星编队构型、轨道高度、与目标的相对位置及卫星定轨精度和测量误差的关系。对模型进行了仿真计算和分析,仿真结果表明:合理增加卫星间的基线长度,保持卫星编队构型及其与目标间相对位置的均匀性可以有效提高卫星对目标的定位精度。 相似文献
72.
Shufan Wu Wen Chen Caixia Cao Chuanxin Zhang Zhongcheng Mu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(11):3712-3724
CubeSats has evolved from purely educational tools, to useful platforms for technology demonstration and many practical applications. This paper reviews a CubeSat constellation mission involving 3 CubeSats launched into orbit on Sep. 25th 2015, aiming to demonstrate the integrated application of low-cost CubeSat technologies with distributed payloads using a group of satellites, as well as to demonstrate several new technologies. The mission scenario, the satellite system design, the innovative technologies and instruments or devices used on the CubeSats and the in-orbit experimental results and the payload data analysis, as well as some experiences and lessons learned, are presented and summaried. 相似文献
73.
Tengxu Zhang WenBin Shen Yuanjin Pan Wei Luan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(4):1005-1016
Lithospheric deformation signal can be detected by combining data from continuous global positioning system (CGPS) and satellite observations from the Gravity Recovery and Climate Experiment (GRACE). In this paper, we use 2.5- to 19-year-long time series from 35 CGPS stations to estimate vertical deformation rates in Nepal, which is located in the southern side of the Himalaya. GPS results were compared with GRACE observations. Principal component analysis was conducted to decompose the time series into three-dimensional principal components (PCs) and spatial eigenvectors. The top three high-order PCs were calculated to correct common mode errors. Both GPS and GRACE observations showed significant seasonal variations. The observed seasonal GPS vertical variations are in good agreement with those from the GRACE-derived results, particularly for changes in surface pressure, non-tidal oceanic mass loading, and hydrologic loading. The GPS-observed rates of vertical deformation obtained for the region suggest both tectonic impact and mass decrease. The rates of vertical crustal deformation were estimated by removing the GRACE-derived hydrological vertical rates from the GPS measurements. Most of the sites located in the southern part of the Main Himalayan Thrust subsided, whereas the northern part mostly showed an uplift. These results may contribute to the understanding of secular vertical crustal deformation in Nepal. 相似文献
74.
激光技术在高技术国防战争中的应用 总被引:1,自引:0,他引:1
介绍激光技术的基本含义以及激光技术在新军事应用中的分类,并结合我军的军事战略,从激光侦查技术、激光对抗与激光干扰技术、激光模拟训练技术以及激光武器四个方面对激光技术在高技术国防战争中的应用进行分析,最后结合装甲装备,介绍激光技术在观瞄系统中的具体应用。 相似文献
75.
敏捷遥感卫星工作模式研究 总被引:14,自引:7,他引:7
综述了国外商业遥感卫星发展情况,归纳总结了高分辨率商业卫星的主要技术指标和特点。在充分调研国外敏捷遥感卫星的基础上,从成像目标需求、分辨率与幅宽关系、立体成像三方面总结出此类卫星的技术特点,阐述了发展敏捷遥感卫星的重要意义和作用,并深入分析了实现姿态敏捷控制的技术途径。利用姿态的敏捷控制能力,研究提出了多点目标成像、立体成像、宽幅拼接成像、动态扫描成像等4种典型工作模式,完成了敏捷卫星主要工作模式的分析与设计,并基于此工作模式要求,提出了敏捷卫星工程实现的技术途径。 相似文献
76.
Introduction to Meridian Space Weather Monitoring Project 总被引:1,自引:0,他引:1
The Meridian Project is a ground- based network program to monitor solar-terrestrial space environment, which consists of a chain of ground-based observatories with multiple instruments including magnetometers, ionosondes, HF and VHF radar, Lidar, IPS monitors, sounding rockets etc. The chain is mainly located in the neighborhood of 120°E meridian, and is thus named the Meridian Project. It has officially been approved by the Chinese government and will be finished by 2009. This talk will give an overview of the Meridian Project and the proposed International Space Weather Meridian Circle Program. 相似文献
77.
Wei Fengsi Feng Xueshang Guo Jian-shan Fan Quanlin Wu Jian 《Space Science Reviews》2003,107(1-2):327-334
Recent progress in space weather research are briefly presented here from three aspects: establishment or improvement in observation
systems, such as extra-soft X-ray detector and γ-ray detector onboard the spacecraft ‘Shen Zhou 2’, new solar radio broad-band
spectrometer, magnetometer-chain, ionosonde and digisonde–chain, laser-lidar system and VHF radar; partial topic progresses
included in CMEs, multi-streamer structures, evolution of interplanetary magnetic field B
z component, regional properties of traveling ionospheric disturbances, a fully-nonlinear global dynamical model for the middle
and upper atmosphere, and a combined prediction method for geomagnetic disturbances; and space weather activity, such as ‘Meridian
Project’ — a national major scientific project, ‘International Space Weather Meridian Circle Program’ — a suggestion of internationalization
of ‘Meridian Project’, ‘Space Weather Research Plan’ — a major research plan from National Natural Science Foundation of China
(NNSFC) and other space weather activities.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
78.
Dynamical simulations have been developed at IASB-BIRA to model the deformations of the plasmasphere during geomagnetic substorms
and other variations in the level of geomagnetic activity. The simulations are based on the mechanism of plasma instability
and use the empirical Kp-dependent electric field E5D. The results of the simulations are compared with IMAGE observations
that provide the first global comprehensive images of the Earth’s plasmasphere. The predicted plasmapause positions correspond
generally rather satisfactorily with the EUV observations. The plasmasphere is rather extended in all MLT sectors during quiet
periods. During or just after geomagnetic substorms, the plasmaspause is sharper and becomes closer to the Earth in the night
sector. Periods of enhanced geomagnetic activity are associated to the formation of plumes that rotate with the plasmasphere.
The simulations reproduce the formation and the motion of these plumes, as well as the development of other structures like
shoulders observed at the plasmapause by EUV on IMAGE. 相似文献
79.
Yanhong Kou Yue Jiao Dongyang Xu Meng Zhang Ya Liu Xiaohui Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Global navigation satellite systems (GNSS) receivers can be used in time and frequency metrology by exploiting stable GNSS time scales. This paper proposes a low-cost method for precise measurement of oscillator frequency instability using a single-frequency software GNSS receiver. The only required hardware is a common radio frequency (RF) data collection device driven by the oscillator under test (OUT). The receiver solves the oscillator frequency error in high time resolution using the carrier Doppler observation and the broadcast ephemeris from one of the available satellites employing the onboard reference atomic frequency standard that is more stable than the OUT. Considering the non-stable and non-Gaussian properties of the frequency error measurement, an unbiased finite impulse response (FIR) filter is employed to obtain robust estimation and filter out measurement noise. The effects of different filter orders and convolution lengths are further discussed. The frequency error of an oven controlled oscillator (OCXO) is measured using live Beidou-2/Compass signals. The results are compared with the synchronous measurement using a specialized phase comparator with the standard coordinated universal time (UTC) signal from the master clock H226 in the national time service center (NTSC) of China as its reference. The Allan deviation (ADEV) estimates using the two methods have a 99.9% correlation coefficient and a 0.6% mean relative difference over 1–1000 s intervals. The experiment demonstrates the effectiveness and high precision of the software receiver method. 相似文献
80.