共查询到18条相似文献，搜索用时 523 毫秒
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差分法周跳探测与修复方法改进 总被引：3，自引：0，他引：3
在目前常用的周跳探测与修复方法基础上，提出了首先将观测资料按照观测历元不连续分成若干小弧段，然后利用差分法进行周跳探测，根据差分后周跳放大的特性判断周跳和野值，并确定其位置利用宽带组合和电离层组合的方法解算周跳大小。通过实例验证了其有效性。 相似文献
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在目前常用的周跳探测与修复方法基础上 ,提出了首先将观测资料按照观测历元不连续分成若干小弧段 ,然后利用差分法进行周跳探测 ,根据差分后周跳放大的特性判断周跳和野值 ,并确定其位置利用宽带组合和电离层组合的方法解算周跳大小。通过实例验证了其有效性。 相似文献
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熊永清 《中国科学院上海天文台年刊》1998,(19):68-73
总结了GPS相位数据预处理中探测周跳和修复周跳的方法,基于对这些方法的理解,介绍了一个比较有效的自动进行周跳修复的软件－－AUTCLN。在它的帮助下,可以减少大量的手工编辑操作,更加有铲地处理GPS数据。 相似文献
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单频GPS周跳检测与估计算法 总被引：22，自引：1，他引：22
提出一种单频GSP载波相位中的野值，周跳俭测与模糊度估计算法，采用三阶多项式的卡尔曼滤波检测野值与周跳，而用一种最佳小波估计模糊度，该算法适用于采样间隔为1秒的载波相位测量，用1995．6．22Topex星载GPS数据计算的结果表明，它有限高的效率，可以准确估计信号中断几秒内的模糊度。 相似文献
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LP估计在星载GPS运动学定轨中的应用及精度分析 总被引：2，自引：0，他引：2
为得到高精度的星载GPS运动学定轨,必须利用观测精度高的相位观测值,但是相位观测值预处理后,仍然存在残余小周跳．在残差服从正态分布情况下LS法是最佳参数解算方法,但该方法不能解决资料的系统误差消除问题,LP估计是处理资料残差分布含有系统误差的有效方法之一．基于LS、LP方法的有效条件和GPS数据预处理的特性,将LP估计方法引入星载GPS运动学定轨数据处理中,以CHAMP卫星资料为例,研究了LP估计在星载GPS运动学定轨中的应用及其精度分析．实践表明:在处理含有残余小周跳的相位观测值时,LP估计比LS更有效,提高了星载GPS运动学定轨精度,但随着残余周跳的进一步修复,LP估计相对于LS估计的优越性越来越弱,在资料完全没有系统误差,残差服从正态分布的情况下,LP估计不能很好地体现其优越性,精度反而低于LS估计． 相似文献
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研究近地小天体的探测机会搜索问题．针对交会型探测任务,通过结合变分理论和状态转移矩阵推导了性能指标关于可调参数的解析偏导数,然后在搜索空间中随机生成初始点,并从这些初始点出发利用解析偏导数寻优,从而得到搜索空间内对应潜在发射机会的全部局部极小值点．此方法既在一定程度上保持了传统搜索方法全局搜索的特点,又克服了传统搜索方法的盲目性,因此计算速度获得很大提高．此外该方法可以对探测机会的搜索精度进行有效地控制． 相似文献
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介绍GIPSY(GNSS-inferred positioning system)中周跳检测与修复的TurboEdit算法,在此基础上对TurboEdit方法的周跳检测条件进行分析,在用宽巷组合检测周跳的过程中采用滑动平均的方法替代宽巷模糊度中对每一历元之前的所有数据整体求平均的方法,同时在用电离层残差组合检测周跳中采用相邻历元的载波相位电离层残差组合求差的方法,从而避免引入观测噪声较大的伪距电离层残差组合。实验表明:改进后的TurboEdit法对于发生在观测数据质量不好时段的周跳、Turboedit法的检测盲点以及频繁周跳的检测能力都有所提高。 相似文献
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《天文和天体物理学研究(英文版)》2020,(7)
Taking a large number of images, the Cassini Imaging Science Subsystem(ISS) has been routinely used in astrometry. In ISS images, disk-resolved objects often lead to false detection of stars that disturb the camera pointing correction. The aim of this study was to develop an automated processing method to remove the false image stars in disk-resolved objects in ISS images. The method included the following steps:extracting edges, segmenting boundary arcs, fitting circles and excluding false image stars. The proposed method was tested using 200 ISS images. Preliminary experimental results show that it can remove the false image stars in more than 95% of ISS images with disk-resolved objects in a fully automatic manner,i.e., outperforming the traditional circle detection based on Circular Hough Transform(CHT) by 17%. In addition, its speed is more than twice as fast as that of the CHT method. It is also more robust(no manual parameter tuning is needed) when compared with CHT. The proposed method was also applied to a set of ISS images of Rhea to eliminate the mismatch in pointing correction in automatic procedure. Experiment results showed that the precision of final astrometry results can be improve by roughly 2 times that of automatic procedure without the method. It proved that the proposed method is helpful in the astrometry of ISS images in a fully automatic manner. 相似文献
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Although the existence of dark matter is generally accepted by the mainstream scientific community, there is no generally agreed direct detection of it. Also, observations show that some Bok globules are prolate in some regions without suitable explanation for its cause. In this paper, we investigate the effect of dark matter sub-halo in transformation of the Bok globules from spherical to the prolate shape. We limit the investigation to a particular case that the magnetic field and turbulent effects are negligible through the Bok globule. We consider the gravitational effect of dark matter sub-halo on the isothermal Bok globule that is exposed to suitable distance of it. The results show that the dark matter sub-halo can justify the transformation of Bok globules in some regions. In this paper, we introduce a new method for proving the existence of dark matter sub halo. 相似文献
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The PLANCK mission, originally devised for cosmological studies, offers the opportunity to observe Solar System objects at millimetric and submillimetric wavelengths. In this paper we concentrate on the asteroids of the Main Belt, a large class of minor bodies in the Solar System. At present, more that 40 000 of these asteroids have been discovered and their detection rate is rapidly increasing. We intend to estimate the number of asteroids that can be detected during the mission and to evaluate the strength of their signal. We have rescaled the instrument sensitivities, calculated by the LFI and HFI teams for sources fixed in the sky, introducing some degradation factors to properly account for moving objects. In this way a detection threshold is derived for asteroidal detection that is related to the diameter of the asteroid and its geocentric distance. We have developed a numerical code that models the detection of asteroids in the LFI and HFI channels during the mission. This code performs a detailed integration of the orbits of the asteroids in the timespan of the mission and identifies those bodies that fall in the beams of PLANCK and their signal strength. According to our simulations, a total of 397 objects will be observed by PLANCK and an asteroidal body will be detected in some beam in 30% of the total sky scan-circles. A significant fraction (in the range from 50 to 100 objects) of the 397 asteroids will be observed with a high S/N ratio. Flux measurements of a large sample of asteroids in the submillimeter and millimeter range are relevant since they allow to analyze the thermal emission and its relation to the surface and regolith properties. Furthermore, it will be possible to check on a wider base, the two standard thermal models, based on a nonrotating or rapidly rotating sphere. Our method can also be used to separate Solar System sources from cosmological sources in the survey. This work is based on PLANCK LFI activities. 相似文献
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从VLBI相关处理结果中提取的延迟值包括了天线、终端等设备的时延,必须对其加以修正,最终结果才能达到精度要求。提取相位校正信号,可以消除这些设备引入的时延,从而校正同一波前信号到达基线两端的几何时延。该文介绍了提取相位校正信号的原理、算法及软件实现方法。软件采用多线程和SSE技术,具备4台站多通道全部相位校正信号提取能力。 相似文献
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近十几年来,人们已经对吸积盘进行了深入的研究。前人很多工作都是解析工作。虽然解析工作能够简单明了地揭示盘的许多重要性质,但吸积盘的很多重要性质(例如:对流和外流)没有办法通过解析工作进行深入的研究。数值模拟是研究天体物理的重要手段。近十年来,随着计算机技术的迅速发展,数值模拟在天体物理研究中扮演了越来越重要的角色。本论文主要用数值模拟的手段研究吸积盘中一些重要的物理过程。 相似文献
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Recently, a configuration using atomic interferometers(AIs) had been suggested for the detection of gravitational waves. A new AI with some additional laser pulses for implementing large momentum transfer was also put forward, in order to reduce the effect of shot noise and laser frequency noise. We use a sensitivity function to analyze all possible configurations of the new AI and to distinguish how many momenta are transferred in a specific configuration. By analyzing the new configuration,we further explore a detection scheme for gravitational waves, in particular, that ameliorates laser frequency noise. We find that the amelioration occurs in such a scheme,but novelly, in some cases, the frequency noise can be canceled completely by using a proper data processing method. 相似文献
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天体搜索是天文数据处理流程的一个重要环节,也是以平方公里阵列射电望远镜(Square Kilometre Array, SKA)为代表的下一代射电望远镜在面向海量数据处理中的挑战之一.现今天体自动搜索算法、软件已日趋成熟并投入应用,不过在自动化、兼容性等方面仍具有提升空间.以更自动化、更适应海量数据需求的天体搜索算法研究为宗旨,以现有算法为研究基础,天体自动搜索软件系统得到设计和开发.该系统包含友好的交互式用户操作界面,具备可视化输出数据显示、兼容不同数据输入和输出并包含为实际应用服务的文件管理功能.该系统对于大天区图以及图像集,均能够很好地进行自动化处理.测试结果显示,上述方法对于天体搜索的改进有一定成效.后续将在此基础上对该集成系统做进一步的改进开发,以适应更多的需求. 相似文献
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Using the method of Morlet wavelet transform, we analysed the sunspot relative numbers and obtained some meaningful results. The solar activity possesses the periods of 10.7a and 101a, and the period of 10.7a is very prominent. The variation of intensity of the solar activity exhibits certain stages. In 1950 there occurred abrupt changes of climate, and since then the solar activity has become more and more intense. It is predicted that it would be weaker for some time interval in the future. 相似文献