高轨导航接收机的时钟辅助定位算法

针对高轨卫星导航接收机接收信号弱、可用卫星少及定位精度差的问题,提出利用恒温晶振的频率稳定性抑制观测噪声,进一步改善定位精度的时钟辅助定位算法。通过区分星历星钟误差和用户测距误差在本算法中的不同传递路径,在理论上给出了算法的定位精度与星座几何构形之间的关系,并指出本算法在高轨场景下具有显著的精度优势,在低轨和地面场景下没有精度优势。仿真试验证实了算法的有效性,在典型的高轨场景下,本算法的单点定位误差仅是标准算法的1/10。     

基于惯性导航/无线传感器网络组合的采煤机定位方法研究

采煤机是井下综采工作面的重要设备,采煤机精确定位技术是煤矿生产装备自动化的关键技术之一。为了实现高精度定位满足井下综采自动化作业需求,提出了基于惯性导航/无线传感器网络组合的采煤机定位方法。采用锚节点安置于液压支架上,移动节点与惯导固定安装于采煤机上的配置方案,利用位置已知的锚节点测距信息估计和修正惯导误差,同时实施对安置于推进过程中的液压支架上锚节点(未知节点)位置信息的实时校准,从而达到采煤机高精度定位、无线传感器网络节点动态自动调节的目的。通过试验对所提方法的有效性进行了验证,结果表明,所釆用方法对釆煤机轨迹具有良好跟踪性能,水平定位误差不超过1.57 cm/h。     

基于无迹卡尔曼滤波的空间目标双星定位方法

利用双星对空间目标的观测角进行目标定位,可以很好地避免地基探测系统探测弧段短的缺点。研究了基于动力学滤波的双星定位方法,介绍了无迹卡尔曼滤波的基本原理,建立了考虑地球非球形J2项引力摄动的空间目标动力学方程和基于无偏量测转换的双星观测方程。通过仿真比较两种滤波方法在相同条件下对目标的定位误差,可知无迹卡尔曼滤波方法在收敛速度和定位精度上均优于扩展卡尔曼滤波方法。     

Closed form algorithm of double-satellite TDOA+AOA localization based on WGS-84 model

In this paper, we consider the double-satellite localization under the earth ellipsoid model of the Wideband Geodetic System(WGS-84) using the Time Difference of Arrival(TDOA)and the Angle-of-Arrival(AOA).Several closed-form solution algorithms via the pseudolinearization of the measurement equations are presented to efficiently estimate the location.These algorithms include the Weighted Least Squares(WLS), the Constrained Total Least Squares(CTLS), and the Taylor-Series Iteration(TSI).Performance comparison of the proposed methods with the Cramér-Rao Lower Bound(CRLB) in the simulation is shown to demonstrate that the proposed algorithms are feasible and have stable performance.     

A new stochastic model considering satellite clock interpolation errors in precise point positioning

Precise clock products are typically interpolated based on the sampling interval of the observational data when they are used for in precise point positioning. However, due to the occurrence of white noise in atomic clocks, a residual component of such noise will inevitable reside within the observations when clock errors are interpolated, and such noise will affect the resolution of the positioning results. In this paper, which is based on a twenty-one-week analysis of the atomic clock noise characteristics of numerous satellites, a new stochastic observation model that considers satellite clock interpolation errors is proposed. First, the systematic error of each satellite in the IGR clock product was extracted using a wavelet de-noising method to obtain the empirical characteristics of atomic clock noise within each clock product. Then, based on those empirical characteristics, a stochastic observation model was structured that considered the satellite clock interpolation errors. Subsequently, the IGR and IGS clock products at different time intervals were used for experimental validation. A verification using 179 stations worldwide from the IGS showed that, compared with the conventional model, the convergence times using the stochastic model proposed in this study were respectively shortened by 4.8% and 4.0% when the IGR and IGS 300-s-interval clock products were used and by 19.1% and 19.4% when the 900-s-interval clock products were used. Furthermore, the disturbances during the initial phase of the calculation were also effectively improved.     

一种IRST双机协同被动探测机动目标定位新方法

针对红外搜索跟踪系统（IRST）双机协同被动探测定位作战使用中，机动目标建模与实际运动失配造成定位误差偏大的问题，研究了一种基于曲线模型的自适应滤波新方法。该方法改进了传统方法根据方向角估计转弯率以及基于帧间插分线加速度估计切向加速度的思路，将转弯率及线加速度联合作为状态变量进行了状态扩维，并推导了扩维后的过程噪声协方差表达式，在缓解传统两层滤波结构带来的计算量大问题外，也提高了切向加速度的估计精度。另外基于反正切函数的值域，结合方向角在四象限间的转移关系，优化了方向角的设计。通过IRST双机协同仿真实例，验证了所提方法对机动目标的适应性更强、目标定位精度更高。     

Satellite availability and positioning performance of uncombined precise point positioning using BeiDou-2 and BeiDou-3 multi-frequency signals

To realize the smooth transition from regional BeiDou Navigation Satellite System (BDS-2) to the global one (BDS-3), the integration of BDS-2 and BDS-3 is important for providing continuous, stable and reliable positioning, navigation and timing (PNT) services for global users. This work used 154 globally distributed multi-GNSS (Global Navigation Satellite System) experiment stations spanning 30 days to analyze the satellite availability and positioning performance of uncombined precise point positioning (UC-PPP) under current BDS-2 and BDS-3 constellations. We focused on three issues: the influence of BDS-3 receiver tracking abilities, the positioning performance among different areas, and the benefit of multi-frequency observations. The results show that the elliptical zone caused by poor BDS-2 satellite visibility is disappeared when the evenly distributed BDS-3 medium earth orbit satellites are introduced. When BDS-3 are integrated with BDS-2, the area with the Position Dilution of Precision (PDOP) less than 2 can be expanded to 75° S-75° N and 30° E-150° W. The positioning performance of BDS-3 and BDS-2/BDS-3 UC-PPP are seriously affected by the receiver tracking abilities of BDS-3 signals. When the maximum pseudo-random noise sequences (PRNs) of BDS-3 satellites tracked by stations are within 30 or 37, the positioning accuracy of static UC-PPP can be improved by 22.94% or 8.27% due to the integration of BDS-2 and BDS-3. Besides, the most improvement of BDS-2 and BDS-3 integration is achieved in Asia-Pacific regions, especially for the kinematic UC-PPP or the poor receiver tracking abilities of BDS-3. Similar to the multi-frequency BDS-2 UC-PPP, the benefit of multi-frequency signals for BDS-3 or BDS-2/BDS-3 UC-PPP is also non-vital. The three-dimensional positioning accuracy of BDS-2/BDS-3 multi-frequency UC-PPP in static mode and kinematic mode are 2.24 cm and 5.39 cm, while the corresponding convergence time are 49.62 min and 73.80 min, respectively. Compared with BDS-2, both the positioning accuracy and the convergence time of BDS-2/BDS-3 joint UC-PPP are improved by approximately over 50%, which indicates that BDS-3 has a great potential to provide high-quality PNT services as other global navigation satellite systems.     

一种面向电力终端的北斗定位模块研究

基于电力系统对卫星导航定位的自主安全性要求，研究用于电力终端的北斗定位技术，设计了一款用于电力行业终端的北斗定位导航模块，主要包括模块的模拟前端设计、数字信号处理及分析，重点对低功耗小型化设计、提高接收灵敏度设计等进行研究，并对所设计的北斗模块实物进行了实际测试和分析，成果已开始在电力行业试点应用。     

基于低轨卫星增强的非差高精度导航定位技术与在轨试验验证

随着自动驾驶、精密农业等领域的发展,各领域对高精度导航定位的需求不断增加。在地基增强技术、高轨星基增强技术和传统非差精密单点定位技术的基础上,提出了一种基于低轨卫星增强的非差高精度导航定位技术,研制了基于低轨导航增强技术的低轨导航增强载荷,开发了基于低轨卫星增强的地面自适应卡尔曼滤波非差高精度定位软件,并进行了全球首次基于低轨卫星的信号信息一体化导航增强在轨试验。试验表明:经低轨卫星增强后,地面终端用户定位精度优于30 cm。最后,给出了该技术的后续研究方向,为未来低轨导航增强系统与其他增强系统协同工作,实现广泛应用奠定了基础。     

基于Hatch滤波法的GPS伪距差分定位分析

利用Hatch滤波法对导航数据进行伪距差分定位研究,对单频接收机采用Hatch滤波法时电离层的影响做进一步研究,分析电离层风暴对定位精度的影响。为了提高定位精度,采用Hatch滤波法辅助的差分定位技术,对解算过程进行详细分析,并通过MATLAB软件对数据进行处理仿真,验证利用差分Hatch滤波法提高定位精度的可行性。