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浏览/检索结果: 共5条，第1-5条 帮助 已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 GNSS time offset monitoring based on the single difference among systems 期刊论文 IET RADAR SONAR AND NAVIGATION, 2020, 卷号: 14, 期号: 2, 页码: 299-302 作者:  Tu, Rui;  Zhang, Pengfei;  Zhang, Rui;  Fan, Lihong;  Liu, Jinhai 收藏  |  浏览/下载：13/0  |  提交时间：2020/11/09 delays  satellite navigation  radio receivers  Global Positioning System  GNSS time  single difference  time offset monitoring  multiple Global Navigation Satellite Systems  compatibility  interoperability  conventional signal space approaches  single-point positioning  SPP  precise point positioning  single-difference point positioning  SDPP  receiver clock parameter  common model errors  estimated time  smooth estimation  time offset estimation  different stations  system biases   Estimation of Satellite-Based SO42- and NH4+ Composition of Ambient Fine Particulate Matter over China Using Chemical Transport Model 期刊论文 REMOTE SENSING, 2017, 卷号: 9, 期号: 8 作者:  Si, Yidan[1];  Li, Shenshen[2];  Chen, Liangfu[3];  Yu, Chao[4];  Zhu, Wende[5] 收藏  |  浏览/下载：10/0  |  提交时间：2019/12/23 PM2.5 chemical components  sulfate  ammonium  satellite-estimated  chemical transport model   Assessment of Three Satellite-Estimated Land Surface Downwelling Shortwave Irradiance Data Sets 期刊论文 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, 2010, 卷号: 7, 期号: 4 作者:  Gui, Sheng;  Liang, Shunlin;  Wang, Kaicun;  Li, Lin;  Zhang, Xiaotong 收藏  |  浏览/下载：3/0  |  提交时间：2019/12/05 Data sets  downwelling shortwave irradiance  satellite-estimated  technology assessment   Analysis of laser jamming to satellite-based detector (EI CONFERENCE) 会议论文 International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China Wang S.-W.; Guo L.-H.; Guo R.-H. 收藏  |  浏览/下载：17/0  |  提交时间：2013/03/25 The reconnaissance satellite  communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites  anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups  but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large  it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain  so laser disturbing satellite detector is possible. In order to determine its feasibility  the theoretical analyses and experimental study are carried out in the paper. Firstly  the influence factors of laser disturbing satellite detector are analyzed in detail  which including laser power density on the surface of the detector after long distance transmission  and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit  but dependence on the following parameters: laser average power in the ground  laser beam quality  tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly  the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away  which the disturbing threshold value is obtained as 3.5510-4mW/cm2 that coincides with other researcher's results. Finally  using the theoretical model  the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100mW/cm2  which is largely exceed the disturbing threshold and therefore verify the feasibility of using this kind of laser disturbing the satellite-based detector. According to the results. using the similar laser power density absolutely saturate the requirements to laser disturbing satellite-based detector. If considering the peak power of pulsed laser  even decrease laser average power  it is also possible to damage the detector. This result will provide the reliable evidences to evaluate the effect of laser disturbing satellite-based detector. 2009 SPIE.   Application of CMOS APS star tracker with large FOV in attitude and angular velocity determination (EI CONFERENCE) 会议论文 Advanced Sensor Systems and Applications III, November 12, 2007 - November 14, 2007, Beijing, China Lu D.; Guang J.; Shaoju W.; Tao C. 收藏  |  浏览/下载：21/0  |  提交时间：2013/03/25 The paper deals with the spacecraft attitude determination problem using a new kind of star tracker with large FOV based on CMOS APS. Star tracker has been developed since 1970s and proved to be the most accurate sensor ever used in the spacecraft attitude determination systems. But the traditional CCD star tracker also has some disadvantages  such as small FOV  high power consumption  low sample rate and low working angular rate limit which prevent the use of CCD star tracker in attitude large angle maneuvering process. The new kind of star tracker based on CMOS APS has no such disadvantages and is more applicable on modern low-cost agile small satellites. Its higher sample rate and working angular rate limit over traditional CCD star tracker make it more adapt for spacecraft angular velocity determination. Because of the large FOV of the star tracker  the mathematical model of traditional CCD star tracker with a small FOV is not appropriate. So a new mathematical model was quoted to fit the star tracker with a large FOV. An alternative adaptive algorithm was also introduced in the paper. It can help the EKF algorithm work lacking of accurate covariance of the observation noise. An optimal estimation algorithm was used to estimate the angular velocity directly from the star tracker measurements. Mathematic simulation results indicate the CMOS APS star tracker can give accurate attitude information and estimated angular rate. The method can be used as the chief attitude determination system design of low-cost satellite without gyros  or be used as a backup strategy in the event of gyro failures to enhance the reliability of the attitude determination system.