KMS of Xinjiang Astronomical Observatory, CAS
| 南山26m 天线轨道高差测量及其对指向精度的影响 | |
| Alternative Title | Measurement of NSRT 26m Antenna Track Unevenness and Influence on Pointing Accuracy |
温浩兴
| |
| Subtype | 硕士 |
| Thesis Advisor | 王娜 |
| 2018-06 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学硕士 |
| Degree Discipline | 天文技术与方法 |
| Keyword | 轨道高差 南山26m天线 整体轨道 十字扫描 指向偏差 |
| Abstract | 指向精度是射电望远镜系统中重要的指标之一，指向精度的高低直接关系到天文观测结果的好坏。影响指向精度的因素很多，可归纳为结构和控制两方面的因素。天线轨道高差是影响天线指向精度的主要因素之一，天线轨道是整个天线的基础，支撑整个天线，实现天线方位方向的运动。轨道面精度会使天线方位轴、俯仰轴、光轴出现偏差，直接影响天线的指向精度。 南山 26m 射电望远镜轨道于2015 年改造完成，轨道更新为11 段弧形整体焊接式轨道。在天线正常运行一段时间后，我们对轨道的整体高差进行了测量。本论文基于中国科学院新疆天文台南山观测站26m 射电望远镜的整体焊接式轨道测量数据，研究了轨道高差对指向的影响，具体工作如下： （1）南山26m 轨道高差测量。由于白天太阳照射温差很大对测量数据的准确性产生较大影响，因此测量时间调整到夜间23:30 以后，此时温差较为均匀，测得的数据比较准确。测量工作使用徕卡高精度水准仪和高度尺，在轨道上布设220 个观测点进行测量。 （2）建立轨道高差计算天线指向偏差模型。天线通过四个轮子跟轨道接触，轨道上四点的高差共同决定天线此位置的指向偏差。基于天线座架的几何分析，建立天线坐标系X-Y-Z，通过天线某一位置所对应的四点高差计算出天线分别绕X、Y、Z 轴转角。根据得到的转角，计算得到天线方位和俯仰的指向偏差，综合得到天线的指向偏差。 （3）实测与本模型计算的指向偏差分析。通过“十字扫描”方法，对多颗标准源进行指向测量，高斯拟合出真实的指向偏差，并与利用本模型算的指向偏差进行对比用以修正指向偏差。 结果表明，指向偏差最大的地方不是天线轨道高差最大的地方，因为指向偏差是通过四点的高差计算得到；采用高精度整体焊接轨道技术后NSRT 天线轨道峰峰值由改造前的1.200mm 提高到0.254mm，满足设计要求的0.450mm；使用本文模型计算得到方位俯仰指向偏差，并对实测的指向偏差进行修正，提高天线指向精度。 |
| Other Abstract | Pointing accuracy is one of the most important specifications in the radio telescope system. The accuracy of pointing is directly related to the quality of the astronomical observation. There are many factors affecting the pointing accuracy, which can be summed up in two aspects of structure and control. Antenna track is the foundation of the whole antenna, supporting the whole antenna and realizing the motion of the antenna's azimuth direction. The unevenness of antenna track is one of the main factors that affect the precision of antenna pointing. Therefore, the accuracy of the track surface will make the antenna azimuth axis, elevation axis and optical axis deviation, and directly affect the pointing accuracy of the antenna. The NSRT 26m radio telescope track was reformed in 2015. And the track was updated to 11 sections of arc welded rail as a whole. The overall unevenness of the track was measured during the normal operation of the antenna for a period of time. This paper is based on the overall welding track measurement data of the NSRT 26m, and study the impact of track height difference on pointing error. The specific work is as follows: (1) Measurement of track height difference. The high temperature produced by the Sun in the daytime have a great impact on the accuracy of the measured data, therefore the measurement time is adjusted to 23:30 at night when the temperature difference is more uniform, and the measured data are more accurate. Using a level and a height ruler, 220 observation points are set up on the track to measure. (2) The calculation of pointing error model for track unevenness. The antenna is in contact with the track through four wheels, and the height difference at four points in the track determines the pointing error. The antenna coordinate system X-Y-Z is set up, and the antenna is calculated by the four point height difference corresponding to one position of the antenna. The deviations of the azimuth and elevation are calculated according to the obtained rotation angle, and the pointing error of the antenna is obtained. (3) Analysis of the pointing error between measured and calculated model. The method of cross scanning of standard sources is used for pointing measurement. Gauss fit is applied for obtaining the true pointing error, and this is validated with a model to compensate for the antenna pointing error. |
| Pages | 40 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/2477 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 温浩兴. 南山26m 天线轨道高差测量及其对指向精度的影响[D]. 北京. 中国科学院大学,2018. |
| Files in This Item: | ||||||
| File Name/Size | DocType | Version | Access | License | ||
| 学位论文-温浩兴.pdf（1816KB） | 学位论文 | 暂不开放 | CC BY-NC-SA | Application Full Text | ||
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