共查询到18条相似文献,搜索用时 125 毫秒
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合成孔径高度计的海面回波仿真 总被引:1,自引:0,他引:1
本文首先采用经验海浪谱仿真了三维海面,进而在此基础上根据镜面反射理论计算了海面小面元散射系数。然后根据雷达方程和合成孔径高度计的合成孔径处理计算了海面回波信号的矩阵,以便给出最终的功率回波。在目前国内外缺少相应试验数据的条件下,验证了合成孔径高度计工作方式的有效性,经验证其回波模型基本正确。同时,为了与传统高度计比较,给出了传统高度计在相同参数下的回波仿真结果。文章还通过展示合成孔径高度计在同种波高、不同涌浪和风浪方向情况下的回波,说明波浪方向也会影响合成孔径高度计回波。 相似文献
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星载雷达高度计系统设计及测高精度分析 总被引:3,自引:1,他引:2
在总结机载海洋雷达高度计研制及其飞行实验的基础上,根据海面回波的性质,设计了一个星载雷达高度计系统。系统工作在脉冲有限足迹方式,发射脉冲为线性调频(Chirp)脉冲,接收系统采用“全去斜坡”技术及频谱分析方法将海面回波信号从时域转换至频域处理,自适应跟踪器可抑制大于75%的噪声,高脉冲重复频率使有效独立脉冲数达到最大,保证最大限度地抑制海面斑点噪声;设计了系统的主要工作模式:双分辨率捕获跟踪模式使海面回波信号的捕获时间小于5s,定标模式可保证系统达到设计的测高精度;分析了主要噪声,即海面斑点噪声和接收机热噪声对高度估值的影响,通过对几种典型海况海面回波的模拟分析表明,系统则高精度可达±2cm。 相似文献
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监测海冰的类型变化或厚度变化是较为有效的海冰监测方式,本文通过CryoSat-2雷达高度计对北极海冰类型开展研究。利用雷达高度计对北极海冰进行分类,一方面是难以挑选出最优特征参数,另一方面单一的雷达高度计数据难以实现海冰的相对精细化分类。针对以上问题,本文构建了一种利用卡方检验、互相关信息及Wrapper包装法组合的特征优选方法,利用该方法挑选出的特征子集(SSD+Sigma0+LTPP+PP+SK+LEW)结合随机森林分类法将北极地区的雷达高度计数据分为海水、一年薄冰、一年厚冰及多年冰。本文方法在训练集分类正确率为93.32%,验证集正确率为92.42%,Kappa系数为0.90,均优于其他特征组合,可以基本实现对北极地区海冰的有效分类,同时分类结果也有助于海冰厚度的反演。 相似文献
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应用求解沿轨迹重力异常的垂线偏差法以及求解空间分辨率的交叉谱分析法,建立了高度计测距精度与沿轨迹重力异常反演精度以及空间分辨率的关联性模型。首先依据卫星测高原理,给出了沿轨迹重力异常的误差传播公式,然后以此为基础通过推导交叉谱分析中一致性系数与信噪比的数学表达式,建立了高度计测距精度与空间分辨率的解析关系。数值仿真结果表明:雷达高度计测距精度与沿轨迹重力异常反演精度成正比关系,与空间分辨率成幂函数关系,即高度计测距精度提高m倍,沿轨迹重力异常反演精度提高m倍,全球海域平均空间分辨率提高m0.464 4倍。将数值仿真结果与相关文献中对实际测高数据的处理结果进行比较,验证了理论分析及模型的正确性。 相似文献
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推导了一般情况下激光站为星载雷达高度计进行绝对定标的数学模型,并进行了仿真验证和误差分析,对高度计定标精度进行了定量评估。利用Corsica定标场区中Grasse激光站对Jason-2卫星定轨的实测数据进行了分析,取得了满意的结果。 相似文献
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Karl-Rudolf Koch 《Journal of Geodesy》1975,49(1):35-40
Summary Two methods are discussed for the processing of altimetry data. For the first method it is assumed that the altimetry data,
may be analyzed independent of the orbit computation for the satellite that carries the altimeter. Because of the high accuracy
of the altimetry data, which can only be fully utilized if it is also introduced into the orbit computations, the second method
deals with a simultaneous processing of altimetry data, orbit tracking, and gravity anomalies for the continents. To represent
the gravity field, the potential of a simple layer is chosen whose unknown density is assumed to be constant over surface
elements into which the surface of the earth is divided. Depending on the accuracy and the amount of the altimetry data, the
surface elements for the density values are chosen smaller or larger, so that a very flexible representation of the earth’s
gravity field is obtained. Because of the amount and the resolution of the altimetry data a large number of density values
have to be determined in a least squares adjustment. To facilitate the computations, buffer zones are introduced so that the
large system of normal equations can be broken up into small independent subsystems.
Shortened version of a paper presented to the 14 th International Congress of Surveyors in Washington, Sept. 1974. 相似文献
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Orbit determination of the SELENE satellites using multi-satellite data types and evaluation of SELENE gravity field models 总被引:1,自引:0,他引:1
S. Goossens K. Matsumoto D. D. Rowlands F. G. Lemoine H. Noda H. Araki 《Journal of Geodesy》2011,85(8):487-504
The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents
a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking
data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far
side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit
determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis.
It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values
in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter
data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an
average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed
through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be
mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the
SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used. 相似文献
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P. Schwintzer C. Reigber A. Bode Z. Kang S. Y. Zhu F.-H. Massmann J. C. Raimondo R. Biancale G. Balmino J. M. Lemoine B. Moynot J. C. Marty F. Barlier Y. Boudon 《Journal of Geodesy》1997,71(4):189-208
Summary. GFZ Potsdam and GRGS Toulouse/Grasse jointly developed a new pair of global models of the Earth's gravity field to satisfy
the requirements of the recent and future geodetic and altimeter satellite missions. A precise gravity model is a prerequisite
for precise satellite orbit restitution, tracking station positioning and altimeter data reduction. According to different
applications envisaged, the new model exists in two parallel versions: the first one being derived exclusively from satellite
tracking data acquired on 34 satellites, the second one further incorporating satellite altimeter data over the oceans and
terrestrial gravity data. The most recent “satellite-only” gravity model is labelled GRIM4-S4 and the “combined” gravity model
GRIM4-C4. The models are solutions in spherical harmonics and have a resolution up to degree and order 60 plus a few resonance
terms in the case of GRIM4-S4, and up to degree/order 72 in the case of GRIM4-C4, corresponding to a spatial resolution of
555 km at the Earth's surface. The gravitational coefficients were estimated in a rigorous least squares adjustment simultaneously
with ocean tidal terms and tracking station position parameters, so that each gravity model is associated with a consistent
ocean tide model and a terrestrial reference frame built up by over 300 optical, laser and Doppler tracking stations. Comprehensive
quality tests with external data and models, and test arc computations over a wide range of satellites have demonstrated the
state-of-the-art capabilities of both solutions in long-wavelength geoid representation and in precise orbit computation.
Received 1 February 1996; Accepted 17 July 1996 相似文献
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TOPEX/Poseidon orbit error assessment 总被引:1,自引:0,他引:1
A. J. E. Smith E. T. Hesper D. C. Kuijper G. J. Mets P. N. A. M. Visser B. A. C. Ambrosius K. F. Wakker 《Journal of Geodesy》1996,70(9):546-553
This paper discusses the accuracy of TOPEX/Poseidon orbits computed at Delft University, Section Space Research & Technology (DUT/SSR&T), from several types of tracking data,i.e. SLR, DORIS, and GPS. To quantify the orbit error, three schemes are presented. The first scheme relies on the direct altimeter observations and the covariance of the JGM-2 gravity field. The second scheme is based on crossover difference residuals while the third scheme uses the differences of dynamic orbit solutions with the GPS reduced-dynamic orbit. All three schemes give comparable results and indicate that the radial orbit error of TOPEX/Poseidon is 3–4 cm. From the orbit comparisons with GPS reduced dynamic, both the along-track and cross-track errors of the dynamic orbit solutions were found to be within 10–15 cm. 相似文献
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国际重力卫星研究进展和我国将来卫星重力测量计划 总被引:12,自引:3,他引:9
本文首先分别介绍了国际已经成功发射的专用地球重力测量卫星CHAMP、GRACE以及即将发射的GOCE、GRACE Follow-On和专用月球重力探测卫星GRAIL的研制机构、轨道参数、关键载荷、跟踪模式、测量原理、科学目标和技术特征;其次,阐述了当前相关学科对地球重力场测量精度的需求;最后,建议我国在将来实施的卫星重力测量计划中首选卫星跟踪卫星高低\低低模式,尽快开展轨道参数优化选取的定量系统研究论证和重力卫星系统的误差分析,依据匹配精度指标先期开展重力卫星各关键载荷的研制以及尽早启动卫星重力测量系统的虚拟仿真研究。 相似文献
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海洋卫星测高在全球和区域大地水准面建模、全球海洋重力场反演、海底地形探测、海平面变化监测、构造板块运动研究等大地测量领域至关重要。本文概述了海洋微波测高卫星的简要发展历程,重点梳理了卫星测高在全球海洋重力场和全球海底地形建模方面取得的丰硕成果,对比分析了主流的海洋重力场和海底地形模型;介绍了合成孔径雷达高度计、Ka频段雷达高度计、合成孔径雷达干涉仪3种先进微波测高技术,并分析了其各自的优缺点,表明它们将在未来若干年呈并驱发展趋势;较为系统地阐述了海洋卫星测高的另一新型技术,即GNSS反射信号测量技术的研究动态,给出了GNSS-R(GNSS reflectometry)类(试验)卫星的发展脉络和发展前景。卫星测高的发展趋势之一是多颗测高卫星的组网观测,本文概括了曾经提出的和拟议中的若干组网测高计划,扼要介绍了由我国提出并正在实施的双星跟飞测高模式;最后指出了卫星测高发展的几个主要关注点,包括双星跟飞测高和SWOT(surface water ocean topography)任务的2维海面高(差)测量、卫星测高反演海底地形与高级地形激光高度计观测数据及遥感卫星图像的结合、星载GNSS-R厘米级海面高的载波相位测量、人工智能技术在卫星测高中的潜在应用等。 相似文献