Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular...Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular calculation,the"solar constant"is regard as a constant.However,due to the existence of sunspots,flares,etc.,the solar constant is not fixed,the change in the year is about 1%.To investigate the variation of solar irradiance,we use interpolation and average segment modeling of total solar irradiance data of SORCE,establishing variance solar radiation pressure(VARSRP)model and average solar radiation pressure(AVESRP)model based on the built solar pressure model(SRPM)(constant model).According to observation data of global positioning system(GPS)and Beidou system(BDS)in 2015 and comparing the solar pressure acceleration of VARSRP,AVESRP and SRPM,the magnitude of change can reach 10-10 m/s^2.In addition,according to the satellite precise orbit determination,for GPS satellites,the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model,and the improvement is between 0.1 to 0.5 mm.For geosynchronous orbit(GEO)satellites of BDS,The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm,respectively,based on overlapping arc,and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm,respectively.Moreover,the change of inclined geosynchronous orbit(IGSO)satellites and medium earth orbit(MEO)satellites is relatively small,and the improvement is smaller than 0.5 mm.展开更多
在全球卫星导航系统(GNSS)中,延长相关累积时间可以有效提高弱信号捕获灵敏度,但是"北斗"中圆地球轨道/倾斜地球同步轨道(MEO/IGSO)卫星信号的捕获性能很大程度上受到二次编码(NH)码的影响:调制NH码的信号在每一个码元周期(1 ...在全球卫星导航系统(GNSS)中,延长相关累积时间可以有效提高弱信号捕获灵敏度,但是"北斗"中圆地球轨道/倾斜地球同步轨道(MEO/IGSO)卫星信号的捕获性能很大程度上受到二次编码(NH)码的影响:调制NH码的信号在每一个码元周期(1 ms)内都有可能发生跳变,对相关累积时间造成一定影响,从而会导致系统捕获灵敏度的下降。为此,提出了一种针对NH码的码元遍历搜索算法,通过遍历累积时间内NH码的所有组合,消除NH码码元引起的误差。实验结果显示,所提算法可以在一定程度上提高卫星信号的捕获成功率,尤其可以至少提高2 d B弱信号的捕获灵敏度。同时,算法可以为信号跟踪提供更加准确的载波频率。展开更多
针对当前推土机在作业过程中操作复杂、施工效果评估困难等问题,基于北斗实时动态差分定位(real time kinematic,RTK)技术和运动学方程,求得推土机实时位置;提出了以推土高程和设计平面的高程差作为平整施工质量评价的方法,可直观评价...针对当前推土机在作业过程中操作复杂、施工效果评估困难等问题,基于北斗实时动态差分定位(real time kinematic,RTK)技术和运动学方程,求得推土机实时位置;提出了以推土高程和设计平面的高程差作为平整施工质量评价的方法,可直观评价施工效果,研制了驾驶引导装置,可实时显示推土机状态与施工进度。工程应用表明,该装置达到了厘米级的定位精度,定位的绝对误差小于5 cm,满足推土机精准施工的需求;车载显示终端使用RS232通信可精确获取推土机坐标、速度、航向等自身状态参数和施工数据。在实际施工场景中,该系统可有效减少驾驶员返工次数、降低劳动强度,提高了施工效率,达到了辅助施工的目的。展开更多
文摘基于后处理精密产品,评估了2015-06-01—2018-06-30北斗广播星历的性能精度.对北斗系统性能精度评估的基准问题进行了讨论,统计分析了北斗系统不同星座卫星的轨道差值与星钟差值的长期变化趋势,表明北斗系统空间信号测距精度有逐年提升的趋势.还发现北斗广播星历在2017-01-17前后做出的调整具有较好的效果,不同卫星轨道径向产生一个非零均值的偏差,分析表明该径向偏差更好地实现了轨道径向与卫星星钟参数的自洽,进而大大提高了北斗系统空间信号测距精度.并且北斗系统在2017-07-22对广播星历TGD参数进行了更新,提高了卫星钟差精度.采用4个MGEX测站数据的伪距单点定位验证北斗空间信号精度提升对北斗系统基本导航定位服务的影响,结果表明北斗系统在2017年2次更新后,北斗基本导航定位精度在NEU三个方向分别提升41%、49%和39%.2018年1—6月的统计结果表明,目前北斗系统的IGSO卫星空间信号测距精度最高,优于0.8 m,GEO与MEO卫星次之,约为1 m.
基金supported by the National Key Research and Development Program of China (No.2016YFB0501405)the National Natural Science Foundation of China (No.11973073)+1 种基金the Basic Project of Ministry of Science and Technology of China (No.2015FY310200)the Shanghai Key Laboratory of Space Navigation and Position Techniques (No.06DZ22101)
文摘Solar radiation pressure is the main driving force and error source for precision orbit determination of navigation satellites.It is proportional to the solar irradiance,which is the"sun constant".In regular calculation,the"solar constant"is regard as a constant.However,due to the existence of sunspots,flares,etc.,the solar constant is not fixed,the change in the year is about 1%.To investigate the variation of solar irradiance,we use interpolation and average segment modeling of total solar irradiance data of SORCE,establishing variance solar radiation pressure(VARSRP)model and average solar radiation pressure(AVESRP)model based on the built solar pressure model(SRPM)(constant model).According to observation data of global positioning system(GPS)and Beidou system(BDS)in 2015 and comparing the solar pressure acceleration of VARSRP,AVESRP and SRPM,the magnitude of change can reach 10-10 m/s^2.In addition,according to the satellite precise orbit determination,for GPS satellites,the results of VARSRP and AVESRP are slightly smaller than those of the SRPM model,and the improvement is between 0.1 to 0.5 mm.For geosynchronous orbit(GEO)satellites of BDS,The AVESRP and VARSRP have an improvement of 3.5 mm and 4.0 mm,respectively,based on overlapping arc,and SLR check results show the AVESRP model and the VARSRP model is improved by 2.3 mm and 3.5 mm,respectively.Moreover,the change of inclined geosynchronous orbit(IGSO)satellites and medium earth orbit(MEO)satellites is relatively small,and the improvement is smaller than 0.5 mm.
文摘在全球卫星导航系统(GNSS)中,延长相关累积时间可以有效提高弱信号捕获灵敏度,但是"北斗"中圆地球轨道/倾斜地球同步轨道(MEO/IGSO)卫星信号的捕获性能很大程度上受到二次编码(NH)码的影响:调制NH码的信号在每一个码元周期(1 ms)内都有可能发生跳变,对相关累积时间造成一定影响,从而会导致系统捕获灵敏度的下降。为此,提出了一种针对NH码的码元遍历搜索算法,通过遍历累积时间内NH码的所有组合,消除NH码码元引起的误差。实验结果显示,所提算法可以在一定程度上提高卫星信号的捕获成功率,尤其可以至少提高2 d B弱信号的捕获灵敏度。同时,算法可以为信号跟踪提供更加准确的载波频率。
文摘针对当前推土机在作业过程中操作复杂、施工效果评估困难等问题,基于北斗实时动态差分定位(real time kinematic,RTK)技术和运动学方程,求得推土机实时位置;提出了以推土高程和设计平面的高程差作为平整施工质量评价的方法,可直观评价施工效果,研制了驾驶引导装置,可实时显示推土机状态与施工进度。工程应用表明,该装置达到了厘米级的定位精度,定位的绝对误差小于5 cm,满足推土机精准施工的需求;车载显示终端使用RS232通信可精确获取推土机坐标、速度、航向等自身状态参数和施工数据。在实际施工场景中,该系统可有效减少驾驶员返工次数、降低劳动强度,提高了施工效率,达到了辅助施工的目的。
