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Volume 44 Issue 10
Oct.  2019
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LI Zongchun, LU Zhiyong, GUO Yinggang, ZHANG Guanyu, HE Hua, FENG Qiqiang, CHEN Shaoqing, WANG Junwei. Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting[J]. Geomatics and Information Science of Wuhan University, 2019, 44(10): 1449-1456. doi: 10.13203/j.whugis20180064
 Citation: LI Zongchun, LU Zhiyong, GUO Yinggang, ZHANG Guanyu, HE Hua, FENG Qiqiang, CHEN Shaoqing, WANG Junwei. Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting[J]. Geomatics and Information Science of Wuhan University, 2019, 44(10): 1449-1456.

# Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting

##### doi: 10.13203/j.whugis20180064
Funds:  The Open Foundation of CETC Key Laboratory of Aerospace Information Applications
• Author Bio:

LI Zongchun, professor, PhD specializes in precise engineering survey. E-mail:13838092876@139.com

• Publish Date: 2019-10-05
• In traditional method, the model of elevation axis fitting is not rigor, which influences the accuracy and reliability of rotation center. To overcome this drawback, two new methods are proposed to get rotation center respectively based on elevation axes intersecting and spherical fitting. The trajectory of target points in different azimuths are fitted to acquire elevation axes which contain azimuth information, and the intersection of elevation axes is taken as rotation center, which is called as the elevation axes intersection method. This method is more reliable than the traditional method. The target points are fitted as a sphere to obtain a series of spherical centers, and their average is taken as the rotation center, which is named as the spherical fitting method. This method avoids the process of circle fitting and axes intersecting, which is more reasonable than the others. An uplink antenna array consists of three φ3 m antennas is taken as experimental object. Total station and industrial photogrammetric system are combined to get the coordinates of points on antenna. By employing the two new proposed methods, the antenna rotation centers are precisely acquired in a sub-millimeter level.
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###### 通讯作者: 陈斌, bchen63@163.com
• 1.

沈阳化工大学材料科学与工程学院 沈阳 110142

Figures(10)  / Tables(10)

## Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting

##### doi: 10.13203/j.whugis20180064
###### 1. Institute of Geospatial Information, Information Engineering University, Zhengzhou 450001, China2. CETC Key Laboratory of Aerospace Information Applications, Shijiazhuang 050081, China
Funds:  The Open Foundation of CETC Key Laboratory of Aerospace Information Applications
• Author Bio:

Abstract: In traditional method, the model of elevation axis fitting is not rigor, which influences the accuracy and reliability of rotation center. To overcome this drawback, two new methods are proposed to get rotation center respectively based on elevation axes intersecting and spherical fitting. The trajectory of target points in different azimuths are fitted to acquire elevation axes which contain azimuth information, and the intersection of elevation axes is taken as rotation center, which is called as the elevation axes intersection method. This method is more reliable than the traditional method. The target points are fitted as a sphere to obtain a series of spherical centers, and their average is taken as the rotation center, which is named as the spherical fitting method. This method avoids the process of circle fitting and axes intersecting, which is more reasonable than the others. An uplink antenna array consists of three φ3 m antennas is taken as experimental object. Total station and industrial photogrammetric system are combined to get the coordinates of points on antenna. By employing the two new proposed methods, the antenna rotation centers are precisely acquired in a sub-millimeter level.

LI Zongchun, LU Zhiyong, GUO Yinggang, ZHANG Guanyu, HE Hua, FENG Qiqiang, CHEN Shaoqing, WANG Junwei. Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting[J]. Geomatics and Information Science of Wuhan University, 2019, 44(10): 1449-1456. doi: 10.13203/j.whugis20180064
 Citation: LI Zongchun, LU Zhiyong, GUO Yinggang, ZHANG Guanyu, HE Hua, FENG Qiqiang, CHEN Shaoqing, WANG Junwei. Two Measuring Methods for Antenna Rotating Center Based on Elevation Axes Intersection and Spherical Fitting[J]. Geomatics and Information Science of Wuhan University, 2019, 44(10): 1449-1456.
• 上行天线组阵技术[1-2]利用多台天线向同一个深空探测器发射上行信号[3]，具有提升系统性能、增强可操作性、降低成本和提高系统运行灵活性等明显优势[4-5]。为了实现各发射信号在目标处的同相合成，需要精确测定各天线参考点的相对位置[6]。具有长基线的天线阵可以支持相关的科学应用，如国际地球参考框架(international terrestrial reference frame，ITRF)的建立和维持[7]、深空探测、射电天文学研究等。ITRF的建立和维持需要综合利用甚长基线干涉测量(very long baseline interferometry，VLBI)、卫星激光测距(satellite laser ranging，SLR)、全球导航卫星系统(global navigation satellite system，GNSS)、多普勒轨道学与无线电定位集成卫星(Doppler orbitography and radiopositioning integrated by satellite，DORIS)等空间大地测量技术来实现[8]，多种大地测量技术的综合利用要求将相应的观测台站并置[9]。并置台站的本地连接[10]误差是构建毫米级精度地球参考框架的重要影响因素[11-12]，这就需要提高天线参考点测量结果的精度和可靠性。为此，本文分析了传统测量方法所存在的缺陷，并就如何获取精密、可靠的天线参考点进行了深入的探讨。

天线旋转中心[13]是指天线方位轴与俯仰轴的交点，通常位于天线内部，不易直接观测，一般通过先观测天线上的标志点，再采用相关算法间接得到。标志点的布设、观测方法以及数据处理方法直接影响着旋转中心的精度和可靠性。

国内外许多学者对天线旋转中心测量方法进行了研究。文献[14]分析讨论了在天线方位旋转受限的条件下，轴拟合、圆拟合等的几何条件对旋转中心精度的影响。文献[15]和文献[16]对VLBI天线参考点的自动监测进行了研究。文献[17]通过三维空间圆拟合来获取方位轴和俯仰轴，两轴相交得到VLBI天线的旋转中心。文献[18]采用旋转天线的方法，运用最小二乘曲线拟合得到旋转中心，外符合精度达到1 cm。文献[19]在上海天文台佘山φ25 m射电望远镜归心测量中，对测量结果进行拟合，取俯仰轴与方位轴交点作为旋转中心，外符合精度达到1 mm。文献[20]在上海天文台φ65 m天马望远镜的方位轴和俯仰轴正交度测量中，通过不同的拟合方式求取方位轴和俯仰轴，对比了各拟合方式的特点。文献[21]对国家授时中心昊平站φ40 m天线的旋转中心进行了测定，在2000国家大地坐标系下的点位精度优于8 mm。文献[22]对利用GNSS数据监测VLBI天线进行了仿真分析，期望对旋转中心实现1 mm级的监测。

以上文献大多应用全站仪测量天线上标志点、拟合方位轴和俯仰轴，取两轴交点为旋转中心，如图 1所示。此方法存在两个缺陷：①标志点数目较少，易受测量误差、结构变形等干扰，测量结果不可靠；②生成俯仰轴的方式不够严密，主要表现为拟合俯仰轴时只在一个方位下进行观测，且标志点轨迹至多能覆盖1/4圆周，不利于圆心的准确拟合，而且受自重变形等因素的影响，用圆拟合标志点运动轨迹会引入模型误差。以上因素导致俯仰轴的测量结果可靠性不高，而方位轴的拟合不受这些因素的影响，这就导致方位轴和俯仰轴精度不匹配，从而影响了旋转中心的精度和可靠性。

Figure 1.  Sketch Map of Generating Traditional Rotation Center

为此，本文拟构建基于俯仰轴相交和球拟合两种天线旋转中心测量方法，以提高旋转中心的测定精度和可靠性。

Reference (22)

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