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Bao Shu Hui Liu Li Wang Guanwen Huang Qin Zhang Zhixin Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(5):1623-1637
Obtaining reliable GNSS uncalibrated phase delay (UPD) or integer clock products is the key to achieving ambiguity-fixed solutions for real-time (RT) precise point positioning (PPP) users. However, due to the influence of RT orbit errors, the quality of UPD/integer clock products estimated with a globally distributed GNSS network is difficult to ensure, thereby affecting the ambiguity resolution (AR) performance of RT-PPP. In this contribution, by fully utilising the consistency of orbital errors in regional GNSS network coverage areas, a method is proposed for estimating regional integer clock products to compensate for RT orbit errors. Based on Centre National d’Études Spatiales (CNES) RT precise products, the regional GPS/BDS integer clock was estimated with a CORS network in the west of China. Results showed that the difference between the estimated regional and CNES global integer clock/bias products was generally less than 5 cm for GPS, whereas clock differences of greater than 10 cm were observed for BDS due to the large RT orbit error. Compared with PPP using global integer clock/bias products, the AR performance of PPP using the regional integer clock was obviously improved for four rover stations. For single GPS, the horizontal and vertical accuracies of ambiguity-fixed PPP solutions were improved by 56.2% and 45.3% on average, respectively, whereas improvements of 67.5% and 50.5% in the horizontal and vertical directions, respectively, were observed for the combined GPS/BDS situation. Based on a regional integer clock, the RMS error of a kinematic ambiguity-fixed PPP solution in the horizontal direction could reach 0.5 cm. In terms of initialisation time, the average time to first fix (TTFF) in combined GPS/BDS PPP was shortened from 18.2 min to 12.7 min. In view of the high AR performance realised with the use of regional integer clocks, this method can be applied to scenarios that require high positioning accuracy, such as deformation monitoring. 相似文献
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为评估光纤陀螺在长期贮存条件下的性能保持期,从光纤陀螺自身的特点出发,根据贮存环境的具体要求,详细分析了加速试验过程中试验应力及应力量值的选取,明确了试验样品的分配及具体试验时间估算方式。通过加速退化的手段得到样品的零偏和标度因数等数据,结合可靠性工程领域的成熟方法和理论,采用灰色系统模型和线性退化模型得到外推时间,计算Weibull分布的形状参数和寿命参数,并根据Arrhenius模型对光纤陀螺的性能保持期进行了预测。试验结果表明,采用ASE光源的0.01(°)/h量级的光纤陀螺,其性能保持期可以超过3a。 相似文献
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天线反射器型面精度是衡量、评价天线质量的重要指标之一,天线型面精度的高低将直接影响天线的电性能指标。大型环形可展开天线型面精度测试,目前多采用高精度工业数字化摄影测量技术进行,在使用高精度数字化摄影测量系统对大型环形可展开天线开展型面测试过程中,系统测量精度主要受摄影基准选用、测量距离、测量靶标大小、测量角度、测量拍照数量、相机参数等多项工艺参数影响。就如何使用数字化摄影测量系统对大型环形可展开天线开展高精度型面测试方法开展研究,通过对高精度长基准尺的设计及布局研究,以及对摄影测量系统最优匹配工艺参数研究及验证,得到一种针对大型环形可展开天线开展高精度型面测试的方法。试验证明,该方法可靠有效,能够满足大型环形可展开天线开展型面高精度测试的测量需求。 相似文献
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光纤陀螺随机调制的理论分析及实验 总被引:4,自引:1,他引:3
偏置稳定性是描述陀螺性能的重要指标,而电路中的交叉干扰是导致陀螺输出漂移的重要原因.采用随机调制的方法能够减小陀螺中交叉干扰产生的输出漂移.采用快速傅立叶变换(FFT)的方法对方波调制和随机调制产生的交叉干扰进行了分析,分析结果表明,采用方波调制时,交叉干扰与方波同频,无法滤除,导致陀螺输出的偏置误差以及陀螺输出对光强的依赖性;而采用随机调制,交叉干扰与方波频率不同,能够滤除,从而减小交叉干扰带来的随机漂移.采用的随机调制为-3π/2,-π/2,π/2,3π/2调制,能够保证陀螺工作点在灵敏度最高的偏置点上,其频谱主要成分为方波基波的偶次谐波,通过陀螺电路中的滤波,能够将其滤掉,消除交叉干扰对陀螺输出带来的干扰.对方波调制和随机调制分别进行了实验,通过实验,证明了该方法的正确性,得到了随机调制能够抑制光纤陀螺中由于交叉干扰产生的输出漂移的结论. 相似文献
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针对高精度光纤陀螺对ASE光源高功率、宽谱宽和低偏振度的应用需求,设计了双程后向ASE光源并进行了仿真和实验验证,研究了铒纤长度为4m、10m和19m的光源光谱特性,分析了泵浦功率、温度的变化对输出功率、平均波长及光谱宽度等参数的影响。结果表明,当铒纤长度为19m时,光源在驱动电流为110mA时的输出功率为4.055mW,光谱宽度为16.63nm,偏振度为1.925%,平均波长随电流的变化量为9.9×10-6/mA。同时,温度实验表明,铒纤长度为19m的光源平均波长随温度的变化量为5.9×10-6/℃。 相似文献
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