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111.
SINS/GPS组合导航系统是一种性能较好的导航系统,它结合了GPS的高精度定位,误差无积累及INS的自主性、实时性等优点。两者的结合可使导航系统的成本下降,可靠性增加,精度提高。本文概要地介绍了SINS/GPS的研究背景、结构组成、建立了系统的总体设计方案,给出详细的软件设计框图.并介绍实现系统各个功能的软件算法。实际应用结果表明:该系统的导航精度、成本、体积等指标均达到了设计要求。 相似文献
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Triggering and synchronization of stick slip: Waiting times and frequency-energy distribution 总被引:1,自引:1,他引:1
Triggering and synchronization are encountered in many geophysical phenomena, including geodynamics. Both these effects are generated by the action of additional forcing, which is much smaller than the main driving force. That means that triggering and synchronization are connected with nonlinear interactions of objects, in this case with initiation of instability in systems that are close to the critical state. In seismic process the main component is the tectonic stress and the additional forcing is exerted by various external impacts like tides, reservoir exploitation, big explosions, magnetic storms, etc.In the paper, the results of laboratory and field experiments on the electromagnetic (EM) initiation and synchronization of mechanical instability (slip) are presented. Slip events were recorded as acoustic emission bursts. In the first series of experiments strong EM pulses were applied to the mechanical system driven close to the critical state, namely, to the (dry) rock samples placed on an inclined supporting sample at the slope angle less than, but close to the critical slip angle. It has been found that EM impact initiates slip with probability P ≈ 0.07 at the voltage ΔV = 1.3 kV and with probability P ≈ 0.2 at ΔV ≈ 10 kV if the EM field is applied parallel to the slip surface (first mode). On the other hand, the application of EM pulse hampers the slip considerably if the EM field is directed perpendicularly to the slip surface (second mode): the slip was not observed even at the angle that was larger than the critical one.In the second series of experiments the periodic EM and mechanical forcing were applied to the standard slider-spring system. It was discovered that periodic EM force of frequency f superimposed on the constant driving force excites periodic microslips of rock samples with double frequency 2f. Combined impact of periodic and constant voltages invokes transition from double frequency synchronization to 1:1 synchronization if the direct component of voltage is larger than the periodic one. Synchronization affects not only waiting times, but also frequency-energy distribution: i. the energy of bursts emitted in synchronized mode have much less scatter than in the absence of the periodic forcing, ii. the sudden decrease of synchronizing forcing is followed by acoustic burst of much larger energy than during forcing.The elementary theory of EM triggering and synchronization is given: the effects are explained by the action of EM ponderomotive (electrostriction) forces, which modify Coulomb stress similar to the well known pore pressure model. The formalism of transition from 1:2 to 1:1 synchronization is considered. 相似文献
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利用GPS OEM板对计算机进行高精度授时的研究 总被引:1,自引:0,他引:1
本文介绍了GPS OEM板的授时原理及计算机内部守时原理;分析了计数器频率的稳定性,提出了修正方案;阐述TN用GPS OEM板对计算机授时的实现过程,并做了时间比对实验。结果表明,计数器频率的漂移对授时精度有较大的影响。经频漂修正后,授时精度和守时精度都得到了很大的改善,最终授时精度优于6μs。 相似文献
116.
基于卫星编队的InSAR系统是一个多基雷达系统,依靠卫星编队构型形成干涉所需的基线。系统在一发多收的工作模式下,协同工作的雷达间必须建立时间同步、相位同步和空间同步。本文根据卫星编队条件下InSAR高程测量的要求,对时间同步的要求进行了研究,在此基础上,分析了时间同步对InSAR系统性能的影响。 相似文献
117.
结合星载寄生式干涉合成孔径雷达(InSAR)的工作原理及高稳定频率源的工作特性,给出了时间和频率同步误差模型。基于该误差模型,分析了时间和频率同步误差对干涉相位的影响,首次推导了同步误差导致的信号去相关。基于星载寄生式InSAR系统的空间几何关系和图像信号模型,详细分析了热噪声、模糊、量化噪声、基线、方位向、配准误差及体散射等去相关效应,给出了考虑上述全部去相关因素时系统的相对测高精度,并仿真分析了以Envisat为主星的寄生式InSAR系统在ASAR雷达7个不同波位下的相对测高性能。理论分析和仿真结果表明,在合理选择轨道和雷达参数的前提下,系统可以达到很好的测高精度。 相似文献
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基于卫星编队InSAR空间同步对系统性能影响的分析 总被引:2,自引:0,他引:2
根据卫星编队条件下InSAR高程测量的要求,对空间同步的要求进行了研究。在此基础上,分析了空间同步对InSAR系统的高程测量精度和分辨率的影响。 相似文献
119.
利用星载GPS接收机进行低轨卫星与卫星时间同步 总被引:1,自引:1,他引:1
研究了利用星载GPS接收机进行低轨卫星与卫星时间同步,探讨了其中的关键技术,以Bernese 5.0软件为基础,对GRACE卫星的星载GPS接收机钟差进行了解算,具体分析了解算结果。 相似文献
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