靶场测量装备中GPS换装北斗卫星导航系统方案设计

目前,根据装备试验要求,利用北斗卫星导航系统全面替换靶场测量装备中所使用的GPS已成为必须开展的工作。如果直接替换,则现有测量系统需重新进行测试,代价较高。为此,结合靶场测量装备实际情况,设计一种基于北斗卫星导航系统,集定位、测姿、授时为一体的便携式信息采集分发系统,系统具备多种对外数据传输接口,无需对现有装备进行较大改造,即可全面实现北斗取代GPS的目的。     

GPS/BDS空间可见性与GDOP分析

先给出了卫星可见性模型,然后给出了GPS/BDS组合几何精度因子(GDOP)计算公式,通过近期一组实测的GPS与BDS星历计算了全球范围内不同观测高度处的组合星座卫星可见性与GDOP值,揭示了卫星可见性与GDOP值随空间观测高度变化的规律。     

沿海验潮站GNSS观测网BDS与GPS基线处理精度分析

为了评估北斗卫星导航系统（BDS）用于验潮站沉降监测的可靠性和精度,该文利用北海区沿海8个验潮站2022年全年的GPS和BDS观测数据,从基线解标准均方根误差、基线重复性和GPS与BDS基线互差等方面对GPS和BDS解算结果进行对比分析。结果表明,BDS基线解的NRMS值在0.17～0.25之间,GPS基线解的NRMS值在0.18～0.23之间,二者基线解的NRMS值基本相当;GPS基线解的长度和各分量基线重复率平均值要小于BDS,从GNSS网固定误差和比例误差看,GPS和BDS的基线长度重复性精度达到10-9～10-8量级,基线东西和南北分量重复性达到10-9量级,基线垂直分量重复性精度达到10-7～10-8量级。在GPS和BDS基线结果互差方面,GPS解算得到的基线长度均要大于BDS,二者平均差值为10.7 mm;东西分量差值最小,其次是南北分量,垂直分量差异最大,南北分量、东西分量和垂直分量差值平均值分别为-8.5 mm、-3.7 mm和10.6 mm。南北分量、东西分量、垂直分量和基线长度差值平均值最大值分别为23.6 mm、20.9 mm、30.4 mm和22.1 mm。总体...     

GPS/BDS组合单点定位算法及结果分析

介绍了GPS、北斗卫星导航系统的时间和坐标系统,并对二者之间的转换和统一进行了概括分析,推导了GPS/BDS组合单点定位的函数模型和随机模型。编制了相应的计算程序,对实测数据进行了处理与分析。结果表明:相对于单系统,GPS/BDS组合系统能够增加可观测卫星数、减小DOP值、提高定位的精度和可靠性,同时也说明算法可行,程序可靠。     

Accuracy assessment of GPS/Acoustic positioning using a Seafloor Acoustic Transponder System

The accuracy of GPS/Acoustic positioning is crucial for monitoring seafloor crustal deformation. However, the slant range residual is currently the only indicator used to evaluate the precision of positioning seafloor transponders. This study employs a unique Seafloor Acoustic Transponder System (SATS) to evaluate the accuracy of GPS/Acoustic seafloor positioning. The SATS has three transponders and an attitude sensor in a single unit, which provides true lengths of transponder baselines and true attitude of the SATS to ensure assessment reliability and validity. The proposed approach was tested through a GPS/Acoustic experiment, in which an off-the-shelf acoustic system was used to collect range measurements. Using GPS/Acoustic geodetic observations, the positions of three transponders on the SATS were estimated by an optimization technique combined with ray-tracing calculations. The accuracy of the GPS/Acoustic seafloor positioning is assessed by comparing the true baselines and attitude with the results derived from the position estimates of the three transponders. A sensitivity analysis is conducted to investigate the robustness of the GPS/Acoustic positioning results to changes of sound speed. Experimental results demonstrate that the use of the SATS can help to assess the validity of the GPS and acoustic travel time measurements in the GPS/Acoustic seafloor positioning.     

机载GPS精密单点定位性能分析

利用地面多基站RTK测量结果和精密单点定位（PPP）测量结果,分析了机载条件下PPP定位、测速性能指标.实验结果表明：机载GPS精密单点定位绝对定位精度在位置、速度上可分别达到0.182 3m和0.024 6m/s,相对定位精度在位置、速度上可分别达到0.1450m和0.024 9m/s.     

Determination of Ocean Tide Loading Displacement by GPS PPP with Priori Information Constraint of NAO99b Global Ocean Tide Model

The published global ocean tide models show good agreement in deep oceans and exhibit differences in complex coastal areas, along with subsequent Ocean Tide Loading Displacement (OTLD) modeling differences. Meanwhile, OTLD parameters (amplitudes and phase lags) derived by Global Positioning System (GPS) Precise Point Positioning (PPP) approach need long time to converge to a stable state and show poor precision of S2, K1, and K2 constituents. Based on the fact that no constraint is imposed in the current kinematic solution, a new method is put forward, in which global ocean tide model predictions are taken as the priori information constraints to speed up the convergence rate and improve the accuracy of the GPS-derived OTLD parameters. First, the data of tide gauge from 01 January 2014 to 31 December 2016 are used to generate the harmonic parameters to evaluate the accuracy of six global ocean tide models and a regional ocean tide model (osu.chinesea.2010). Osu.chinesea.2010 model shows good agreement with the tide gauge results, while NAO99b model presents relatively large difference. The predictions from osu.chinesea.2010 and NAO99b model are employed as reference and the prior information, respectively. Second, continuous observations of 12 GPS sites during 2006–2013 in Hong Kong are collected to generate three dimensional OTLD amplitudes and phase lags of eight constituents using PPP with prior information constraints approach and harmonic analysis. Third, comparing the convergence time of eight constituents from PPP without and with priori information constraints approaches, the results show that the new method can significantly improve the convergence rate of OTLD amplitude estimates which obtain a certain level of stability seven years earlier than that derived by the PPP without priori information constraints. Precision of OTLD parameters derived by the new method is about 1 mm. By comparing with the precision of single PPP approach, the accuracy of eight constituents has been improved, especially for S2, K1, and K2 constituents. Finally, through comparing the different correction effects of OTLD estimates on the coordinates and their time series of the ground GPS stations, the results show that OTLD estimates derived by the new approach have similar influence as the osu.chinasea.2010 ocean tide model. The new method provides an effective means to improve the convergence and precision of the GPS-derived OTLD parameters, and achieve a similar correction as the high precision ocean tide model.     

Ocean Tides Observed from A GPS Receiver on Floating Sea Ice Near Chinese Zhongshan Station,Antarctica

Due to limit of coverage in TOPEX/Poseidon (T/P) satellite and sparseness of in-situ tide gauges around Antarctica, the accuracy of global ocean tide models in Antarctic seas is relatively poorer than in low- and mid-latitude regions. To better understand ocean tides in Prydz Bay, east Antarctica, a GPS receiver was deployed on floating sea ice to measure tide-induced ice motion in multiple campaigns. Four online Precise Point Positioning (PPP) services are used to process the GPS data in the kinematic PPP mode, and UTide software is used to separate the major tidal constituents. Comparison between results from different processing methods (relative processing solutions from Track, kinematic PPP solutions from online services) and with bottom pressure gauge (BPG) shows that, high-accuracy tidal information can be obtained from GPS observations on floating sea ice, the root-sum-square (RSS) for the eight major constituents (O1, K1, P1, Q1, M2, S2, N2, K2) is below 4 cm. We have also studied the impacts of data span and filter edge effects at daily boundaries on the accuracy of tide estimates, and found that to obtain reliable tide estimates and neglect the filter edge effects, continuous observation longer than 30 days is necessary. Our study suggests that GPS provides an independent method to estimate tides in Prydz Bay, and can be an alternative to tidal gauges, which are costly and hard to maintain in Antarctica.     

GPS测速精度分析与应用

全球定位系统(GPS)技术的出现,为速度测量提供了新的手段。基于GPS测速的基本原理,采用单点定位模式、无线电信标/差分GPS模式和GPS RTK模式,研究了不同模式下速度测量的方法和精度概况,重点分析了GPS RTK模式下的测速精度,并对高精度速度测量应用提出了建议。     

Bancroft算法在多卫星导航定位系统解算中的推广应用

提出了一种改进的Bancroft算法运用于组合双系统SPP解算。为检验新算法的解算精度,选取2013年2月采集于武汉大学实验大楼楼顶的GPS/BD双频双模接收机实测数据进行解算。实验结果表明改进的Bancroft算法与传统的最小二乘算法的解算精度相当,其解算效率与最小二乘算法相比提高了22%,从而验证了改进的Bancroft算法在组合双系统SPP解算中的可行性及优越性。     

精密单点定位技术在海上工程中的应用

结合海上科研工程实践,对GPS精密单点定位模型及数据处理方法进行研究,并采取陆上静动态定位和海上动态定位试验进行了精密单点定位精度统计和分析。结果表明:在超出常规差分定位基线长度限制的广阔海域,采用精密单点定位技术可实现亚米级实时动态定位,为海上高精度实时动态定位应用提供了技术依据。     

Survey of underwater robot positioning navigation

Underwater robot positioning and navigation achieve autonomous underwater robot movement based on the premise that positioning obtains the coordinates of the relative position of the underwater robot using a sensor, and navigation yields a known location to the destination path planning. Due to the location of an underwater robot and the complex and changing environment in which it operates, it is difficult to achieve precise positioning using the traditional positioning method. This paper systematically analyzes and summarizes several typical localization and navigation methods of underwater robots, such as multisensor information fusion technology, underwater acoustic localization and navigation methods, GPS buoy, underwater vision, SLAM and coordinate localization and navigation of multiple underwater robots. Multisensory information fusion technology integrates the advantages of the above methods, enhances the system stability and robustness, overcomes the disadvantages of traditional positioning and navigation, and enables the autonomous navigation and positioning of underwater robots. Underwater acoustics enable flexible and convenient positioning, whereas GPS can achieve high-precision and high-positioning navigation information, and visual positioning effectively overcomes the problem of error accumulation. Multirobot cooperative positioning resolves the problem of positioning failure caused by the collapse of a single system and completes complex tasks that cannot be completed by a single robot, thus enhancing the stability and robustness of the system. This paper systematically describes the realization of these methods, presents an actual analysis of their respective advantages and problems, and discusses the development of the field of research prospects and application prospects.     

Evaluation of vertical crustal movements and sea level changes around Greenland from GPS and tide gauge observations

To better monitor the vertical crustal movements and sea level changes around Greenland, multiple data sources were used in this paper, including global positioning system(GPS), tide gauge, satellite gravimetry, satellite altimetry, glacial isostatic adjustment(GIA). First, the observations of more than 50 GPS stations from the international GNSS service(IGS) and Greenland network(GNET) in 2007–2018 were processed and the common mode error(CME) was eliminated with using the principal component analysis(PCA). The results show that all GPS stations show an uplift trend and the stations in southern Greenland have a higher vertical speed. Second, by deducting the influence of GIA, the impact of current Gr IS mass changes on GPS stations was analysed, and the GIA-corrected vertical velocity of the GPS is in good agreement with the vertical velocity obtained by gravity recovery and climate experiment(GRACE). Third, the absolute sea level change around Greenland at 4 gauge stations was obtained by combining relative sea level derived from tide gauge observations and crustal uplift rates derived from GPS observations, and was validated by sea level products of satellite altimetry. The results show that although the mass loss of Gr IS can cause considerable global sea level rise, eustatic movements along the coasts of Greenland are quite complex under different mechanisms of sea level changes.     

Undifferenced Cycle Slip Estimation of Triple-Frequency BeiDou Signals with Ionosphere Prediction

With the rapid development of BeiDou satellite navigation system (BDS), high-quality service has been provided in the Asia-Pacific region currently, which will be extended to the whole world very soon. BDS is the first Global Navigation Satellite System that all satellites broadcast the triple-frequency signals. The triple-frequency signals in theory can improve the cycle slip detection that is one of the preconditions in precise positioning by making use of carrier phase. This paper discusses the development of a cycle slip detection method for undifferenced BDS triple-frequency observations in kinematic scenario. In this method, two geometry-free extra-wide-lane combinations and one geometry-free narrow-lane (NL) combinations are employed. The key is to mitigate the between-epoch ionospheric biases in the geometry-free NL combinations. We propose to predict the ionospheric biases of current epoch by using those from its consecutive foregoing epochs. The method is tested with extensive experiments in varying observation scenarios. The results show that in case of sampling interval as small as 5 s, the between-epoch ionospheric biases can be ignored and the correct cycle slips can be determined. Meanwhile in case of lower sampling frequency, one needs to compensate the ionospheric biases of current epoch by using the predicted ionospheric biases. The presented method can correctly detect all cycle slips even if they are as small as 1 cycle.     

精密单点定位中双频GPS数据的周跳探测与修复

周跳的探测与修复,特别是小周跳的探测是实现GPS高精度实时定位的关键技术基础之一。分析了非差相位观测值线性组合模式,比较了几种周跳修复的方法,得出宽巷和电离层组合方法更适用于精密单点定位中双频GPS数据的周跳探测和修复。通过实例分析,证明该方法能够有效地探测并修复周跳。     

GPS/GLONASS组合单点定位精度分析

介绍了GPS/GLONASS组合导航定位的基本原理,分析了需要解决的技术难点,比较了4阶、8阶RK(Runge-Kutta)数值积分方法,针对GPS、GLONASS两类观测值合理定权进行了讨论,利用一组实测数据,进行了组合定位的实际计算,分析了不同方案的伪距实时定位精度。     

GPS技术在城市交通状况实时检测技术中的应用

该文介绍 1种检测城市交通状况的新方法。在利用 GPS对车辆的定位与导航的基础上 ,进一步利用 GPS提供的即时速度和准确的时间信息 ,通过数学建模 ,得到交通流量、平均车速、行程时间、车道占有率等一系列重要交通状况信息 ,以实现交通状况的实时检测 ,为城市交通管理系统智能化的实现提供必要保证。     

GPS精密单点定位数据解算的精度对比

分别采用GAMIT和GrafNav两种不同的软件对南海区域不同时间、不同地点所测得的GPS精密单点定位数据进行了解算,并对同一数据的解算结果进行了精度分析。研究结果表明:这两种方法解算所得结果互差达到厘米级,说明GrafNav满足GPS精密单点定位数据解算要求,具有一定的应用参考价值。     

GPSRTK技术在舰船抗冲击试验中的应用

在舰船实船海上抗冲击试验中,需要对爆源与被试舰的相对位置关系进行实时定位监测。对基于GPSRTK技术的试验定位系统的设计思路、工作原理、数据处理方法、组成与实现等方面进行了阐述,最后介绍了系统应用效果。     

Performance of Real-Time Precise Point Positioning

The IGS Real-time Pilot Project (IGS-RTPP) provides real-time precise orbits and clocks, which support real-time positioning for single stations over large areas using the Precise Point Positioning (PPP) technique. This paper investigates the impact of real-time orbits, network configuration, and analysis strategies on real-time PPP implementation and demonstrates the real-time PPP performance. One month of data from the IGS network is analyzed in a real-time simulation mode. Results reveal the following: (1) In clock estimation, differential approaches are much more efficient than the zero-differenced approach. (2) The precision of IGS Ultra rapid (IGU) orbits could meet the IGS-RTPP requirement for precise clock estimation and PPP positioning. (3) Considering efficiency and precision, a network with 50 stations is recommended for the IGS-RTPP. It is demonstrated that the real-time satellite clock precision is 0.1 ns supporting hourly static PPP with a mean precision of 2–3 cm in the North component and 3–4 cm in the other components. Kinematic PPP assessed with onboard GPS data collected from a buoy provided mean coordinate precision of 2.2, 4.2, 6.1 cm in the North, East and Up directions, compared to the RTK solutions.