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张良云 《中国民航学院学报》1991,9(3):32-40
LTN-72R 惯性导航系统是一个高可靠性、全天候、全球惯导系统。它可单套惯导系统工作,也可作三重位置混合系统工作。惯性即时位置可以使用无线电测距和全向信标导航装置自动更新。本文介绍单套惯导系统、三重位置混合、自动无线电位置更新的基本原理和方法。 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(1):560-571
The precise point positioning (PPP) technique is widely used in time and frequency applications. Because of the real-time service (RTS) project of the International GNSS Service, we can use the PPP technique for real-time clock comparison and monitoring. As a participant in the RTS, the Centre National d’Etudes Spatiales (CNES) implements the PPPWIZARD (Precise Point Positioning with Integer and Zero-difference Ambiguity Resolution Demonstrator) project to validate carrier phase ambiguity resolution. Unlike the Integer-PPP (IPPP) of the CNES, fixing ambiguities in the post-processing mode, the PPPWIZARD operates in the real-time mode, which is also called real-time IPPP (RT-IPPP). This paper focuses on applying the RT-IPPP for real-time clock comparison and monitoring. We review the principle of real-time clock comparison and monitoring, and introduce the methodology of the RT-IPPP technique. The observations of GPS, GLONASS and Galileo were processed for the experiments. Five processing modes were provided in the experiment to analyze the benefits of ambiguity resolution and multi-GNSS. In the clock comparison experiment, the average reduction ratios of standard deviations with respect to the G PPP mode range from 9.7% to 35.0%. In the clock monitoring experiment, G PPP mode can detect clock jumps whose magnitudes are larger than 0.9 ns. The RT-IPPP technique with GRE PPP AR (G) mode allows for the detection of any clock jumps larger than 0.6 ns. For frequency monitoring, G PPP mode allows detection of frequency changes larger than 1.1 × 10−14. When the RT-IPPP technique is applied, monitoring with GRE PPP AR (G) mode can detect frequency changes larger than 6.1 × 10−15. 相似文献
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F. Fund F. Perosanz L. Testut S. Loyer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
GPS data dedicated to sea surface observation are usually processed using differential techniques. Unfortunately, the precision of resulting kinematic positions is baseline-length dependent. So, high precision sea surface observations using differential GPS techniques are limited to coasts, lakes, and rivers. Recent improvements in GPS satellite products (orbits, clocks, and phase biases) make phase ambiguity fixing at the zero difference level achievable and opens up the observation of the sea surface without geographical constraints. This paper recalls the concept of the Integer Precise Point Positioning technique and discusses the precision of GPS buoy positioning. A sequential version of the GINS software has been implemented to achieve single epoch GPS positioning. We used 1 Hz data from a two week GPS campaign conducted in the Kerguelen Islands. A GPS buoy has been moored close to a radar gauge and 90 m away from a permanent GPS station. This infrastructure offers the opportunity to compare both kinematic Integer Precise Point Positioning and classical differential GPS positioning techniques to in situ radar gauge data. We found that Precise Point Positioning results are not significantly biased with respect to radar gauge data and that horizontal time series are consistent with differential processing at the sub-centimetre precision level. Nevertheless, standard deviations of height time series with respect to radar gauge data are typically [4–5] cm. The dominant driver for noise at this level is attributed to errors in tropospheric estimates which propagate into position solutions. 相似文献
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在轨运行热环境下的天线镜面热变形对空地激光通信链路的影响 总被引:3,自引:0,他引:3
针对光学天线镜面热变形对空地激光通信链路性能产生影响的问题进行了理论和仿真分析。采用ANSYS有限元分析软件仿真得到的结果表明:低轨卫星在轨运行热环境条件下,采用潜望式结构且暴露在卫星舱外的光学天线反射镜镜面热变形将导致天线镜面法向偏转,其偏转量在不能释放热应力条件下可达几十μrad量级,经其传输的光束将产生较大的指向偏差;对所提出的释放热应力效果较好的天线镜体安装方式进行的相应分析表明:镜面变形受到镜体固定方式的影响非常大,在一定的参数条件下,和压板法固定方式相比较,压圈固定方式受到热变形影响形成的法向角度偏转较小。 相似文献
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航天器姿控及有效载荷设备总装时, 其安装精度是保证分系统正常工作、完成任务的关键技术指标之一。文章基于型号实践, 依据我国现有航天器的结构类型及设备安装特点, 论述了航天器结构本体在各种工作环境、各个阶段对航天器设备总装的精度影响要素;提出了分析、验证方法以及保证精度及可靠性的措施。可对未来的航天器型号的结构设计、总装设计、工艺及测量实施提供参考。 相似文献
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分析了航空发动机附件机匣轴承衬套采用松螺纹固定的结构在高温时失效的原因。提出了过盈螺纹螺桩固定方案,通过理论分析及试验器试验,验证了改进措施的有效性和可靠性。 相似文献