Automated and continual determination of radio telescope reference points with sub-mm accuracy: results from a campaign at the Onsala Space Observatory

The Global Geodetic Observing System (GGOS) requires sub-mm accuracy, automated and continual determinations of the so-called local tie vectors at co-location stations. Co-location stations host instrumentation for several space geodetic techniques and the local tie surveys involve the relative geometry of the reference points of these instruments. Thus, these reference points need to be determined in a common coordinate system, which is a particular challenge for rotating equipment like radio telescopes for geodetic Very Long Baseline Interferometry. In this work we describe a concept to achieve automated and continual determinations of radio telescope reference points with sub-mm accuracy. We developed a monitoring system, including Java-based sensor communication for automated surveys, network adjustment and further data analysis. This monitoring system was tested during a monitoring campaign performed at the Onsala Space Observatory in the summer of 2012. The results obtained in this campaign show that it is possible to perform automated determination of a radio telescope reference point during normal operations of the telescope. Accuracies on the sub-mm level can be achieved, and continual determinations can be realized by repeated determinations and recursive estimation methods.     

ITRF中GNSS/SLR并址站归心基线的“一步解”

提出将SLR望远镜的参考点和两轴偏差作为未知参数,在ITRF中联合并址站归心测量中GNSS基线网和地面网观测量（水平方向、垂直角和边长）,建立SLR站观测设备的参考点与观测标志、观测标志之间、参考点和两轴偏差与其他未知参数之间的多种约束条件来求解归心基线的“一步解”。利用“一步解”解算出“陆态网络”中北京、昆明和西安3个GNSS/SLR并址站在ITRF2014中的归心基线及其协方差阵。结果显示：归心基线的中误差优于2 mm,与已有分步解相比,差值不超过2 mm;水平轴和垂直轴之间的偏差分别为3.8、0.7和3.6 mm,中误差分别为1.3、1.2和1.3 mm。     

使用参照物的射电望远镜中心坐标测量方法

为满足新建射电望远镜在单站或多站联合进行的深空探测或射电天文观测对中心坐标精确测定的要求,提出一种利用已知精确中心坐标的望远镜作为参照物,测量地平式射电望远镜中心点坐标的方法和测量数据处理方法。这一方法对场地和设备的要求较低,能够得到毫米级或亚毫米级的位置精度。尤其适合对天线阵列的中心位置进行测量。对国家天文台密云观测站的40 m射电望远镜进行了中心坐标测量,位置均方根误差为2.312 mm,满足了后续的观测工作对其位置的需求。     

基于SDCORS的网络RTK在工程测量中的精度分析

针对基于SDCORS网络RTK测量精度进行研究,通过实验分别对两种GPS接收机安置方式的测量精度进行对比,并对网络RTK测量精度的时间变化进行分析,结果表明:1)网络RTK平面控制测量时应该使用三脚架安置GPS接收机。对于高程测量,利用三脚架与对中杆安置GPS接收机对大地高程测量精度影响较小;2)网络RTK测量偶有大误差测量结果出现,应取多次观测结果进行成果检核;3)网络RTK测量相近历元的观测误差具有相关性,如果有条件,最好在不同时间段多次测量取平均值。     

桥梁与隧道GPS网的设计与应用

计算了江阴公路长江大桥GPS网所能达到的精度,阐述了隧道GPS网布设的一般规律,对长梁山13km隧道实测GPS网进行了计算。从比较分析可以看出:1)GPS网能够满足桥梁和隧道工程的精度要求;2)在GPS网中适当加入一些高精度的边长有利于提高GPS网的精度和可靠性,并使得最后GPS网的尺度与施工测量时保持一致;3)GPS用于隧道与桥梁工程测量具有精度高、工期短、效益高等特点。     

Data transformation for super-totalstation positioning system integrated by GPS and totalstation

This paper focuses on the integration and data transformation between GPS and totalstation.It emphasizes on the way to transfer the WGS84 Cartesian coordinates to the local two-dimensional plane coordinates and the orthometric height GPS receiver,totalstation,radio,notebook computer and the corresponding solftware work,together to form a new surveying system(SPS) and a new surveying model for terrestrial surveying.With the help of this system,the positions of detail points can be measured.     

Height bias and scale effect induced by antenna gravitational deformations in geodetic VLBI data analysis

The impact of signal path variations (SPVs) caused by antenna gravitational deformations on geodetic very long baseline interferometry (VLBI) results is evaluated for the first time. Elevation-dependent models of SPV for Medicina and Noto (Italy) telescopes were derived from a combination of terrestrial surveying methods to account for gravitational deformations. After applying these models in geodetic VLBI data analysis, estimates of the antenna reference point positions are shifted upward by 8.9 and 6.7 mm, respectively. The impact on other parameters is negligible. To simulate the impact of antenna gravitational deformations on the entire VLBI network, lacking measurements for other telescopes, we rescaled the SPV models of Medicina and Noto for other antennas according to their size. The effects of the simulations are changes in VLBI heights in the range [−3, 73] mm and a net scale increase of 0.3–0.8 ppb. The height bias is larger than random errors of VLBI position estimates, implying the possibility of significant scale distortions related to antenna gravitational deformations. This demonstrates the need to precisely measure gravitational deformations of other VLBI telescopes, to derive their precise SPV models and to apply them in routine geodetic data analysis.     

港珠澳大桥沉管隧道施工控制网布设研究

针对港珠澳大桥沉管隧道特殊的测量环境和超高的贯通精度要求,对其施工平面控制问题进行了研究。依据测量误差分配理论,研究了长距离沉管隧道贯通误差的合理分配方案;采用贯通误差严密估算方法,分析了沉管隧道内外控制网横向贯通误差影响规律。提出了一种适宜沉管隧道结构的双线形联合锁网布测方法,通过陆地上1:1模拟试验和工程实际应用验证了双线形联合锁网的精度和可靠性。与全导线网相比,其平面控制精度提高15%~30%,平均多余观测分量提高约4%,能够满足外海超长沉管隧道的贯通精度要求,有效保障了工程的精准贯通。     

润扬大桥北汊桥施工控制网测量及分析

通过对润扬大桥北汊桥施工控制网三种测量方案的设计，并对实测成果进行分析比较。根据实践成果得出大型桥梁控制网测量采用测边网或边角网方案可以达到精密施工控制网的精度要求，边角网平差计算采用验后定权法较合理。在精密测距边角网中，通过增加方向观测值方法来提高控制网的精度作用不明显。     

Design of high precision horizontal control network for large-scale hydropower project

A new solution of combination network of GPS and high precise distance measurements with EDM is proposed. Meanwhile, it's inadvisable only using GPS network without distance measurements. Three schemes: terrestrial network, GPS network and combination network are discussed for horizontal control network design of Xiangjiaba Dam in view of precision, reliability, coordinate and outlay in detail.     

Design of high precision horizontal control network for large-scale hydropower project

IntroductionThe design of high precision horizontal controlnetwork for large-scale hydropower project toconstruct control network and measure deforma-tion of monitoring network.It can be also divid-ed into horizontal control network and verticalcontrol ne…     

A Method for Surveying Control Network Optimization Based on Reliability Properties

Surveying control network optimization design is related to standards,such as precision,reliability,sensitivity and the cost,and these standards are related closely to each other.A new method for surve...     

大型桥梁高程控制网的布设和精度分析

结合一个大型桥梁施工控制网测量项目,详细介绍了高程工程网的布设和测量等工作,精度分析结果表明,控制网的布设和测量方案是合理的。     

大型射电望远镜背架精密安装技术

对65 m射电望远镜的背架安装做了尝试,取得较满意的结果.针对天线背架尺寸大、质量重、焊接变形大、几何精度要求高等特性,采用全站仪工业测量系统实现背架的快速、无接触、高精度定位测量,点位测量精度优于1 mm;采用独特的施工工艺和焊接技术,最大限度控制焊接变形,最终点位偏差优于1.5 cm.提出基于设计坐标系建立安装测量...     

CCTV主楼施工变形监测技术应用研究

以中央电视台新址主楼工程为背景,介绍了塔楼1和塔楼2的变形测量监测方案。根据现场条件建立平面及高程变形监测基准控制网和建筑物内部控制网;根据监测点的位置和特点,平面位移监测分别采用内部观测和外部观测方法;高程监测分别采用几何水准和静力水准测量方法施测,保证了监测成果的准确性和可靠性。对倾斜超高层建筑的变形监测在理论和实践中作了有益的探索。     

剥蚀法计算GPS观测网独立环闭合差

在GPS测量中，往往需要计算三角形、多边形闭合差，以便及时发现观测粗差、衡量GPS观测精度。本文提出了剥蚀法计算GPS观测网独立环闭合差，这种方法利用计算机自动确定观测网中的独立环个数，并计算所有独立环闭合差。它适合各种复杂的观测图形，所计算的独立环个数是唯一的，独立环为观测网中的最小闭合单元，并且环与环之间不出现包含和重复。     

基于网络RTK图根控制测量数据后处理及分析

GPS网络RTK技术在工程应用领域发展比较迅猛,目前国内许多城市已经建立了自己的网络RTK系统,将其大面积应用于工程测量领域,而对其采集的数据精度再分析及改进没有相关的研究,文章将结合工程实践及自由网平差理论提出改进网络RTK图根控制点点组整体精度的方法,通过比较研究得出的结论使观测数据精度进一步提高,对网络RTK观测数据误差研究具有参考价值。     

二塘沟水库施工控制网平面坐标系的建立和观测

通过对二塘沟水库库区地理位置的分析,得出该地区每公里变形值较大,为满足施工放样精度及业主建设水库的进场公路和下一级水库规划使用的要求,根据二塘沟现有的测绘资料,建立了二塘沟水库施工控制网平面坐标系。采用三等GPS网进行观测,通过统计测量精度,得出该测量精度高等优点。     

控制网选点系统的研究

为适应城市、工矿地区测图和各种工程的需要,无论采用GPS观测或是常规控制方法观测均需要建立一定精度和密度的控制网。根据任务要求,拟定合理的观测方案,在图上设计出一个图形结构较强、点位分布较好的网形。设计好的控制网,是否合乎实际,还需要到实地验证,最终确定控制点的适宜位置。在Visual Basic设计的选点系统里,对控制网的精度与可靠性进行估算,用AutoCAD读入地形图再一次进行图形的编辑与精度查看。正是由于省掉了不必要的选点工作,使得选点工作变得更具条理性。同时网点总数的降低,也节省了一定的经济开销,所以本系统具有一定的经济价值。     

流动VLBI选址探讨

本文结合流动VLBI参加的"地壳运动观测网络工程"和"探月工程",从建立和维护我国地心参考框架和深空探测两个角度讨论了流动VLBI站址的选择、以及所选站址对我国VLBI观测网的改善。提出了将流动VLBI站设在海南,这样既增加了南北基线长度,也扩大了可观测射电源的范围,同时在建立和维持我国地心参考框架方面也是较好的选择。