Satellite orbit determination combining C-band ranging and differenced ranges by transfer

The constraint in the transverse direction of satellite orbit with differenced ranges between master station and slave stations by transfer as an angular observation data is explained in theory. Differenced ranges in combination with C-band ranging by transfer were used in satellite orbit determination. The position error of overlapped orbit differences for combining is less than that for ranging only. The residual of predicted orbit forward 5.5 days for combining is 3.1762 m, while the residual for ranging only with the same duration is 3.5380 m. Both the orbital overlapping and orbit prediction experimentations can testify the constraint in the transverse direction of satellite orbit with differenced ranges, and the results show that the accuracy of orbit determination and orbit prediction is improved by combining differenced ranges and C-band ranging.     

Variation of satellite transponder delay

For precise orbit determination of geosynchronous earth orbit(GEO)satellites using transfer ranging observations,it is generally assumed that the variation of the satellite transponder delay is very small and that it can be solved as a constant parameter together with satellite orbit parameters.However,this assumption is too general and it reduces the accuracy of orbit determination for GEO satellites.To study and analyse the impact of the satellite transponder delay on GEO satellites orbit determination,two schemes were proposed.First,the satellite transponder delay was eliminated by forming single-difference observations between two ground stations;second,the satellite transponder delay was described as a constant parameter.The preliminary results demonstrate a difference of about1–2 m between the two schemes when used for precise orbit determination of GEO satellites.By fixing the GEO satellite orbit and other relevant parameters estimated by single-difference model,we inversed the instantaneous transponder delay from non-difference observation.It was found that the satellite transponder delay has a distinct diurnal variation,with an amplitude of 3–4 m.The findings of this paper are helpful in establishing an accurate model of satellite transponder delay and in improving the accuracy of GEO satellites orbit determinations and predictions.     

Improvement of orbit determination for geostationary satellites with VLBI tracking

China’s COMPASS satellite navigation system consists of five or more geostationary (GEO) satellites.The roles of GEO satellites are to improve the regional user’s positioning accuracy and provide the continuous Radio Determination Satellite Service.The motion of GEO satellites relative to a ground tracking station is almost fixed,and regular orbit maneuvers are necessary to maintain the satellites’ allocated positions above the equator.These features present difficulties in precise orbit determination (POD).C-band ranging via onboard transponders and the L-band pseudo-ranging technique have been used in the COMPASS system.This paper introduces VLBI tracking,which has been successfully employed in the Chinese lunar exploration programs Chang’E-1 and Chang’E-2,to the POD of GEO satellites.In contrast to ranging,which measures distances between a GEO satellite and an observer,VLBI is an angular measurement technique that constrains the satellite’s position errors perpendicular to the satellite-to-observer direction.As a demonstration,the Chinese VLBI Network organized a tracking and orbit-determination experiment for a GEO navigation satellite lasting 24 h.This paper uses the VLBI delay and delay-rate data,in combination with C-band ranging data,to determine the GEO satellite’s orbit.The accuracies of the VLBI delay and delay rate data are about 3.6 ns and 0.4 ps/s,respectively.Data analysis shows that the VLBI data are able to calibrate systematic errors of the C-band ranging data,and the combination of the two observations improves orbit prediction accuracy with short-arc data,which is important for orbital recovery after maneuvers of GEO satellites.With the implementation of VLBI2010,it is possible for VLBI to be applied in the COMPASS satellite navigation system.     

GEO导航卫星多种观测资料联合精密定轨

针对跟踪站少、观测几何条件差以及轨道机动后GEO导航卫星精密定轨问题,提出了用激光观测数据解算无线电测距离观测数据设备时延、用CODE模型参数和多频载波相位数据进行电离层延迟精确修正的精密定轨和轨道快速恢复的处理体制.通过在轨实测数据实验证明,利用激光标定的距离观测数据组合设备时延精度优于1ns;基于3站观测数据GEO卫星精密定轨结果,RMS为0.25m;24h数据定轨结果重叠12小轨道径向互差0.55m,位置互差约1.62m;预报12h轨道重叠弧段互差为径向3.63m,位置互差8.51m;定轨结果与激光比对残差约0.10m,预报2h轨道比对残差约0.18m,预报24h轨道比对残差约2.04m.GEO卫星轨道机动后2～3h,动力学定轨结果能够恢复到与激光比对残差小于1m、与精密定轨结果比对位置互差约30m的水平.试验及分析结果表明,所提出的GEO精度定轨技术方案可靠、稳定.     

Precise orbit determination of Haiyang-2 using satellite laser ranging

With the successful launch and official commissioning of China’s first dynamic ocean environment satellite Haiyang-2(HY-2),China’s capabilities for oceanic environment monitoring and oceanic resource detecting have been further improved and enhanced.Precise tracking and orbit determination are not only key technical concerns in the ocean dynamic environment satellite project but also necessary conditions for carrying out related oceanic science research using observational data obtained using spaceborne instruments including radar altimeter.In this study,the current available status of international satellite laser ranging(SLR) monitoring on HY-2 was introduced.Six-months of SLR data from HY-2 were processed to obtain precise satellite orbit information using the dynamic orbit determination method.We carried out a detailed assessment of the SLR orbit accuracy by internal evaluation,comparisons with the orbit derived by the French Doppler orbitography and radio-positioning integrated by satellite(DORIS) system,and station-satellite distance validation.These assessments indicate that the three-dimensional orbital accuracy of HY-2 is about 12.5 cm,and the radial accuracy is better than 3 cm.It provides a good example of the application of international SLR monitoring and precise orbit determination in China’s earth observation satellite project.     

一点多星轨道计算精度研究

应用理论分析和计算机模拟相结合的方法,讨论了卫星动力学模型中多种误差因素对一点多星轨道计算精度的不同影响,给出了星间相对位置计算的主要误差因素及其限制要求．并在此基础上,对一点多星的轨道计算和跟踪测量方法,提出了一些可行的建议     

Precise orbit determination for geostationary satellites with multiple tracking techniques

A new precise orbit determination (POD) strategy based on the combination of satellite laser ranging (SLR) and C-band transfer ranging for geostationary satellites (GEO) is presented.Two approaches to calibrate ranging biases of the C-band ranging system are proposed,namely the two tracking system co-location comparison and the combined POD method,with calibration accuracies estimated to be 0.5 ns and 1 ns respectively.Using data from a C-band tracking network in China,POD experiments indicate that meter-le...     

北斗卫星整网集中式自主定轨算法研究

由于分布式定轨算法只能得到局部次优解,为进一步提升北斗卫星自主导航算法精度,对北斗卫星整网 集中式定轨算法在轨实现方法进行研究。设计了基于推广卡尔曼滤波算法的整网集中式定轨算法及其在轨实 现流程,并利用北斗卫星上的龙芯1E300 处理器对算法精度及工程可行性进行了评估。仿真结果表明,整网集 中式算法精度优于分布式导航算法。且通过在龙芯1E300 处理器上仿真验证可知,集中式导航算法已具备星 上使用条件。     

基于TDOA的卫星干扰源定位方法的研究

针对到达时间差/到达频率差（time difference of arrival /frequency difference of arrival,TDOA/FDOA）卫星干扰源定位系统中卫星速度难以准确预测,导致定位精度不高,尤其是在参考站数量较少时,定位误差较大的问题,提出了采用TDOA方法实现高精度单参考站卫星干扰源定位。研究了TDOA卫星干扰源定位原理,建立了定位数学模型,采用信赖域算法计算干扰源的位置,进行了定位方法实验验证,分析了定位误差。通过对实测卫星信号的定位试验,证实了该定位方法在单参考站条件下显著提高卫星干扰源定位精度的有效性。     

对日本测地卫星的观测和分析

本文介绍了日本发射的测地卫星及广州，上海对它的观测，用本文计算卫星轨道的方法，发现该卫星的轨道比原计划要低得多，而其他轨道根数正常，并对其原因作了探讨，本文认为，该卫星的交光方式可以提高卫生的瞬时亮度，但宜缩小卫星的直径，以减少大气和光压摄动以卫星质心改正，提高激光测距精度。     

基于国家测绘局GPS连续运行参考站的定轨

为了解决采用地面GPS连续运行参考站进行高精度定轨问题,采用轨道积分方法,利用国家测绘局8个GPS连续运行参考站和9个中国周边IGS连续运行参考站,设计了多种天数的区域性定轨计算方案,研究了轨道确定的理论、步骤和参数设置规律.结果表明:3天轨道解的平均精度为0.19 m,5天轨道解的平均精度为O.21 m,7天轨道解的平均精度为O.28 m,3天解平均定轨精度最高,优于0.2 m,证明了并非随着地面数据天数的增加而精度随之增加,可以用最少的数据量获得最优的定轨结果.定轨试验计算的是区域性轨道,与全球轨道相比,存在一定的偏差.该成果对我国定轨研究特别是未来的广域增强系统轨道预测具有一定的指导意义和参考价值.     

星载GPS非差精密定轨精度分析

采用一种变相的“非差”动力定轨方法，建立了相应的数学模型，编制了星栽GPS低轨卫星的定轨软件，并以此分析了定轨过程中各主要误差源对定轨的影响以及所能达到的定轨精度和预报精度。该方法以相位平滑伪距为观测值，通过对同一历元的现测值进行卫星间求差，消除了星栽GPS接收机钟差，模型简单，求解参数少。在只估计初始坐标和速度参数、考虑各种误差的综合影响时，定轨一天的径向精度约为3m，能满足一定的定轨精度要求。     

一种新的适用于环保领域的计算机数据采集与通信系统

本文提出一种新的计算机数据采集与通信系统。主要特点是中心站对各子站具有监视和控制双重功能;数据通信误码率低,数据捕获率高以及运行可靠性强。两年的实际运行证实了本系统用于环保领域的有效性。     

基于校正分布差异的标定迁移方法研究

针对近红外光谱数据的维度高、特征之间存在严重的多重共线性的特点,提出了无迁移标准的通过校正分布差异的标定迁移方法(calibration transfer via correcting distributions difference,CT-CDD).CT-CDD首先建立主仪器的偏最小二乘模型,然后通过偏最小二乘模型提取主仪器和从仪器的潜变量,并且分别对主仪器和从仪器的潜变量进行聚类.该方法基于这样的假设:聚类后的主仪器和从仪器的每一部分特征光谱均服从单高斯分布.最后,找到2个仪器的最接近的子分布,通过校正均值和方差来校正数据分布的差异.实验结果表明CT-CDD通常更加鲁棒并且还可以实现最低的均方根预测误差.     

北斗三号GEO卫星的RDSS定轨精度分析

有源服务模式RDSS(Radio Determination Satellite Service)所具备的通信、导航一体化特性是我国北斗卫星导航系统的重要特色之一.为进一步提高RDSS的通信服务能力,并保障RDSS服务系统的健壮性,北斗三号RDSS服务从系统架构到信号体制都进行了很大改进.本文首先分析了新的信号体制下,RDSS测距在测量模型和观测噪声等方面的误差特性,并比较了其与原有信号体制的不同.为了避免在RNSS(Radio Navigation Satellite Service)载荷故障时RDSS不能正常提供导航服务的情况发生,RDSS系统需要能够仅利用RDSS测距完成GEO测轨,以此作为原有RNSS测轨的备份保障.文章进一步分析了这种情况下,仅利用RDSS测距进行GEO定轨的精度.通过实测数据分析,我们发现其精度可优于10 m,利用该轨道信息的定位、定时精度可以满足服务指标要求.     

北斗单系统及多全球导航卫星系统组合极区定位性能

为了评估北斗单系统(BeiDou satellite navigation system,BDS)及多全球导航卫星系统(global navigation satellite sys-tem,GNSS)在极区环境下的导航定位性能,从可见卫星数、位置精度因子、定位精度和高度角变化等多个性能指标对南北极四个测站进行分析.首...     

基于S7协议通信的自动生产线拆装与调试实训装置改造研究

提出了一种基于S7通信协议的自动生产线拆装与调试实训装置改造研究,该方案以S7-1200 PLC为一级主站,西门子TP170B为二级主站,S7-200 Smart PLC、变频器V20为从站。重点研究了主站与各从站的通信方式。     

舰船在风浪干扰下的快速传递对准技术研究

对舰船应用环境下的快速传递对准技术进行了研究.推导了主惯导与子惯导之间姿态之差的动态方程,采用Kalman滤波技术估计子惯导系统的安装误差角.设计了在不依赖舰船有意识机动情况下而仅仅依靠外界风浪的干扰就能实施快速传递对准的方法.仿真结果表明,在10 s内,子惯导系统安装误差角估计可以达到优于1 mrad的精度.     

共享单车发展下的轨道交通廊道影响范围研究

基于共享单车在各大城市普及程度的提高,共享单车换乘轨道交通的出行方式越来越普遍。本文建立以广义出行成本表达可达性的轨道交通廊道影响范围测算模型,计算轨道交通站点的合理影响范围,比较骑行和步行换乘轨道交通时各站点的影响范围。以成都市为例,各环线内骑共享单车的影响范围比步行的影响范围平均增加了675.2～4590.06 m;范围扩大了2.36～2.64倍。基于泰森多边形原理,解决各站点间合理影响范围的重合问题,并确定站点潜在影响范围的界限。该研究成果确定了一个更为精准地划分轨道交通廊道影响范围的方法,为轨道交通廊道影响范围的研究提供了新的理论方法。     

同步轨道卫星实时测定轨方法

同步轨道卫星由于其"静止"特性,用多台站时间比对技术精确测定地面站到卫星间的伪距。而在以伪距为观测量的测定轨中,观测方程和动力学方程都是非线性的。为了避免线性化方程带来的误差,并满足实时性要求,该文提出用无味Kalman滤波(unscented Kalman filtering,UKF)法。实验是用5个距离拉开的测轨站采集的实测数据,并通过计算机仿真验证,仿真结果表明UKF法测定轨结果随机误差明显减小,而且满足实时性要求。