作者：王红闯 程连柱

摘要：目前，城镇地籍测量采用的主要方法是常规GPs结合传统测量技术。这种方法的缺点是：在进行静态控制测量无法获得控制点的实时坐标，单基站RTK测量作业距离受到限制。本文通过一个实例证明：在进行城镇地籍测量中，采用CORS的网络RTK技术来进行城镇地籍侧量各项精度指标都可以达到规范的要求，而且能够减少劳动强度，提高城镇地籍测量的工作效率，完全可以代替常规仪器来进行城镇地籍测量工作。 

    关键词： CORS     网络RTK    工作原理    城镇地籍测量 

    中图分类号：P23    文献标识码：A    文章编号：1674一3695一（2009)04一07一02 

    1 引言

    随着全球定位系统（GPS）技术的快速发展，特别是GPS RTK技术在工程测量中的应用，因其精度高、实时性和高效性强，在很大程度上提高了作业质量和工作效率。而近年来，发展出了一种更为高效和先进的技术一连续运行参考站系统（CORS）技术。而此技术中的网络RTK成为因为其经济性和高效性，成为测绘技术中的新宠。本文结合生产实践经验介绍了网络RTK技术城镇地籍测量中的应用，供读者参考。 

    2 网络RTK基本工作原理

    CORS系统由参考站子系统、数据处理中心子系统、数据通信子系统和用户应用子系统四部分组成。各子系统由数据通信子系统互联，形成一个分布于整个城市的局域网。

    CORS是在一个较大的区域内均匀的布设多参考站，构成一个参考站网，各参考站按设定的采样率连续观测，通过数据通信系统实时的将观测数据传输给系统控制中心，系统控制中心首先对各个站的数据进行预处理和质量分析，然后对整个数据进行同意解算，实时估算出网内的各种系统误差改正项（电离层、对流层、卫星轨道误差）获得本区域的误差改正模型。把改正数据传给流动站，获得高精度的可靠的定位结果。

    网络RTK技术是CORS产生最重要原因和最主要的应用方式。目前，我国大多数CORS系统建立最主要的是进行网络RTK测量，网络RTK技术与常规RTK技术相比，不论是在作业范围、测量精度、可靠性和高效性方面，都是测量技术的巨大进步。 

    CORS目前主要的几种网络RTK技术有虚拟参考站（VRS）技术、主辅站技术（i一MAx）、区域改正参数（FKP）技术和综合误差内插法技术等。 

    3 zzc0Rs（郑州连续运行卫星定位综合服务系统）简介 

    zzCORS于2008年4月开始建设，2008年8月投人使用。共有7个参考站组成，数据中心与各个参考站点通过架设的光纤专线进行数据交换，政府专网作为备份线路。系统完全覆盖郑州市7446.2平方公里。ZZCORS能够全年365天，每天24小时连续不断地运行，全面取代常规大地测量控制网。用户只需一台GPS接收机即可进行毫米级、厘米级、分米级、米级的实时、准实时的快速定位、事后定位。通过建设zzCORS系统，建立城市空间基础设施的三维动态地心坐标参考框架，同时建立起城市独立坐标、国家坐标（北京54、西安80、CGCS2000）和国际标准地心坐标（WGS84)转换关系，通过已建立的似大地水准面模型，实现由大地高到正常高的转换，建立郑州市的统一的坐标基准。彻底解决了郑州市各部门之间坐标系统的差异问题。经过几个月的运行和工作中的使用，无论在工作效率和测量精度等方面，都取得了明显的提高。 

    4 网络RTK技术在城镇地籍测量中的应用实例 

    4.1工程概述

   测区位于郑州市某城区，该城区为行政区和商业区，建筑物密集、楼层较高，交通繁忙，街道两旁树木密集。本次需测量的宗地地块遍布整个城区，总测量面积约40平方公里，权属关系复杂，用地种类较多，宗地数目多，权属界址点数量大。我们过去采用的是单基站RTK作业模式，由于距离测区较远，已超出了RTK的控制范围。如果采用常规测量手段施测十分困难，很难在短时间内完成这么大量的地籍测量工作。由于我们正好刚刚建立起了郑州连续运行卫星定位综合服务系统（ZZCORS)，因而在本次城镇地籍测量采用ZZCORS作为首级控制测量，网络RTK技术直接测量界址点和细部地物点，部分隐蔽地区，加密图根点配合用全站仪实测。采用CORS技术作为进行城镇地籍测量，在我院还是第一次，在《城镇地籍测量规范》和《全球卫星定位系统技术规范》等相关的技术规范中也没有关于CORS应用的具体要求，因此，本次测量可作为网络RTK应用领域的一个有益尝试。为确保测量的精度，我们首先选取测区内4平方公里的范围作为试验区，先进行精度测试和分析，再进行整个测区的工作。 

    4.2 试验区内网络R丁K精度检验

   首先选取试验区范围内，用网络RTK测量原4个E级GPS控制点，并加密6个图根控制点和10个宗地权属界址点。在进行RTK控制测量观测时要注意以下几点要求：l）观测时使用三脚架，仪器架设要严格对中、整平并量取天线高；2）流动站接收机只有经过初始化完成后才能进行RTK测量；3)RTK作业前要进行严格的卫星预报，选取PDoP<6，卫星数＞6的时间进行测量；4)RTK测量时进行两个时段的观测，并进行坐标较差检核，符合限差要求的，取两次测量的平均数作为控制点坐标。然后采用静态GPS测量技术、全站仪测量技术测量，按《城市测量规范》和《全球定位系统城市测量技术规程》中的要求进行复测。将这些测量结果、已知成果与网络RTK测量结果相比较，其较差列于下表中。

    4.3 网络R丁K精度分析

   根据上表统计结果可以看到：网络RTK测量结果与其他常规测量技术获取的测量结果都在厘米级，较差最大值为1.7厘米，最小值为0.1厘米，平均较差1.1厘米。检测点位中误差为：0.8厘米。因此ZZCORS技术中的网络RTK完全可以用于本次城镇地籍测量的图根控制和界址点测量。  

    4.4地籍控制测量 

    在试验区成功经验的基础上，开始测区的地籍测量工作。先进行地籍控制测量，选点埋石参照《城镇地籍测量规范》的要求，为保证观测精度的可靠，在开始观测时，要先检测测区内的已知点，校核无误后，方可开始测量。 

    整个测区内共测设控制点800个，为保证整个控制网的精度，减少人为错误，对这些控制点抽取50%进行复测比较，并统计最大点位较差为1.5厘米，整个点位中误差为0.8厘米。 

    4.5 界址点和细部测量

   界址点和细部点采用网络RTK或全站仪野外实测坐标。当使用RTK时要先用图根控制点进行校核，符合限差要求时，才能开始测量。当采用全站仪用解析交会、极坐标法等方法施测界址点时，当设置好测站后，至少要检核一个除本站和后视点以外的已知点，以保证实测的精度。以全部界址点的解析坐标和解析边长为基础，测出其他地籍、地形要素的几何图形，并依据宗地草图的有关数据检核后成地籍图。 

    5 结束语

    利用网络RTK进行控制测量不受大气、地形、通视等条件的限制，控制测量操作简便、机动性强，工作效率比传统方法提高数倍，大大节省人力，不仅完全能够达到地籍控制测量和界址点的精度要求，而且误差分布均匀，不存在误差积累问题。比起单基站RTK技术来说，更是克服了随着作业半径的增大，精度和可靠性降低的作业瓶颈。同时也要注意以下问题：为保证网络RTK测量精度，尽可能地检测一定数量的测区内和相邻的控制点进行检核；在做控制测量时需采用一些如延长测量时间、选择最佳观测时段、增加观测次数的方法来提高测量精度；同精度两次测量值的较差取2厘米以下为宜。

参考文献：

[1]黄俊华，陈文森．连续卫星定位综合服务系统建设与应用．北京．科学出版社，2009.1

[2]李元征，黄劲松．GPS测量与数据处理．武汉：武汉大学出版社，2007.1

[3]王勇，吴俐民．网络RTK技术在城市控制测量中的试验与研究[J]，城市勘测，2006年04期

Abstract: At present, Cadastral Survey is the primary means used by conventional GPs combining the traditional measurement techniques. Disadvantage of this approach are: making a static control surveying unable to obtain real-time coordinates of control points, single-base RTK measurement of operating distance is limited. In this paper, an example of that: Before Cadastral Survey, using CORS Network RTK technology to carry out the amount of Cadastral side of the precision index can achieve specification requirements, but also can reduce labor intensity and improve the efficiency of the Cadastral Survey, can replace the conventional instrument to carry out Cadastral survey work.

     Key words: CORS network RTK works Cadastral Survey

     Key words: P23 Abstract: A Article ID: 1674 1 3695 1 (2009) 04 1 07 1 02

     1 Introduction

     With the global positioning system (GPS) technology, rapid development, especially the GPS RTK technology in the engineering survey of the application, because of its high accuracy, real-time and efficiency is strong, in large part to improve the quality and efficiency of operations. In recent years, developed a more efficient and advanced technology a Continuously Operating Reference Station System (CORS) technology. And this technology's network RTK into because of its economy and efficiency to become the new darling of mapping technology. This paper describes practical experience in the production of network RTK technology Cadastral Survey for readers reference.

     Two basic working principle of the network RTK

     CORS reference station system consists of subsystems, data processing center subsystems, data communications subsystems and user applications subsystems four parts. The various subsystems interconnected by a data communication subsystem to form a local area network distributed throughout the city.

     CORS is in a large area evenly laid multiple reference stations, constitutes a reference station network, the reference station by setting a sampling rate of continuous observation, through data communication systems will be observed real-time data transmission to the system control center, the system Control Center data for all stations first pre-process and quality analysis, and then agreed that the entire data solver, real-time estimate the net systematic error correction of a variety of items (ionosphere, troposphere, satellite orbit errors) was the region error correction model. Mobile stations to transmit correction data to obtain reliable high-precision positioning results.

     CORS Network RTK technology is the most important cause of produce and the application of the most important way. At present, most of the CORS system is most important is the establishment of the network RTK measurement, network RTK, compared with conventional RTK technology, whether in the operating range, measurement accuracy, reliability and efficiency, the measurement techniques are the tremendous progress in .

     CORS is currently the major types of network RTK technology Virtual Reference Station (VRS) technology, the main auxiliary station technology (i 1 MAx), the regional correction parameters (FKP) technology and integrated error in interpolation technology.

     3 zzc0Rs (Zhengzhou continuous operation of integrated services satellite positioning system) Overview

     zzCORS in April 2008 began construction in August 2008 to vote for human use. A total of seven reference stations, data centers and various reference sites set up fiber-optic line through the data exchange, the Government has special network as a backup line. System is fully covered in Zhengzhou City, 7446.2 square kilometers. ZZCORS to 365 days a year to run continuously 24 hours a day, completely replace the conventional geodetic control network. Users only need a single GPS receiver can be carried out millimeter, centimeter, decimeter level, meter-scale, real-time, quasi real-time fast positioning, after positioning. By building zzCORS system, the establishment of infrastructure in urban space the three-dimensional dynamic geocentric coordinate reference frame, while building urban independent coordinates, the state coordinates (54, Beijing, Xi'an 80, CGCS2000) and international standards in geocentric coordinates (WGS84) conversion relationship, through the established quasi-geoid model, to achieve a high from the earth to the normal high conversion, the establishment of a unified coordinate Zhengzhou benchmark. Completely settled among the various departments in Zhengzhou coordinate system differences. After several months of operation and the use of the work, both in efficiency and accuracy, etc., have made remarkable improvement.

     4 Network RTK technology in the Cadastral Survey Applications

     4.1 Project Overview

    Measurement area is located in Zhengzhou city, a city, the urban area for the administrative and commercial, building density, the higher floors with heavy traffic and dense trees along the street. The measurements were required to land all over the city, with a total area measuring about 40 square kilometers, the complex relationship between ownership, land use types are more the number of cases to more than ownership of the large number of boundary points. We have used a single-base RTK mode of operation, as far away from the surveyed area has been beyond the control of RTK. If the test facilities using conventional means of measurement is very difficult, it is difficult to achieve so much in a short time cadastral survey work. Since we just recently established a continuous operation of satellite positioning, Zhengzhou Integrated Service System (ZZCORS), and therefore in this first-stage Cadastral measured by ZZCORS as a control measure, the network RTK technology, direct measurement of boundary point and the detailed features in point, part of the hidden region, the root point with the encryption map measured with the total station. Use of CORS technology, to serve as a Cadastral measurements in our hospital is the first time in the "Cadastral Survey norms" and "global satellite positioning system specification" and other relevant technical specifications there is no specific requirements on the CORS applications, therefore, the measurements can be used as the network RTK applications in a useful attempt. In order to ensure measurement accuracy, we first select the range of measuring four square kilometers area as a pilot area and made a precision measurement and analysis, and then carry out the work of the entire surveyed area.

     4.2 Test area network R Ding K Precision Test

    First, within the selected test area, using the network RTK measurements of the original four E-class GPS control points, and encryption 6 Topographic Control Points and 10 cases of land ownership boundary points. RTK Control Survey during observation should pay attention to the following requirements: l) observed the use of a tripod, equipment set up to strictly right in the amount of leveling and taking the antenna is high; 2) The mobile station receiver can be completed only after initialization for RTK measurement; 3) RTK operation before strict satellite prediction, select PDoP <6, Number of Satellites "6 measured the time; 4) RTK measurements carried out two periods of observation, and the coordinate less check, meet the limit of bad requirements, taking the average of two measurements as the control point coordinates. Then static GPS measurement techniques, measurement techniques to measure total station, according to "urban measurement norms" and "Global Positioning System Technical Specification for Urban Survey" in the retest request. The results of these measurements, the results are known to the network RTK measurements compared to its poor out in the following table.



     4.3 Accuracy Analysis of the network R Ding K

    Based on the statistical results can be seen in Table: Network RTK measurement results with other conventional measurement techniques to obtain the measurement results are in cm level, less a maximum of 1.7 centimeters, the minimum is 0.1 cm, with an average 1.1 centimeters less. Detection point and the error is: 0.8 centimeters. So ZZCORS Network RTK technology can be used in this graph Cadastral Survey Control and Boundary-point measurements of the root.

     4.4 Cadastral Control Survey

     Successful experience in the pilot area, based on the cadastral surveyed area began survey work. First conduct a cadastral control survey, the Commission buried stone reference points, "Cadastral Survey Standards" requirements in order to ensure the accuracy of observation and reliable, at the beginning of observation, the first test measured the area known points, checking correct only after the beginning measurements.

     The entire test area measuring a total of 800 control points set up in order to ensure the accuracy of the entire control network, reduce human error, these control points at 50% for re-measurement comparisons and statistical maximum point and lower 1.5 cm, the counting of bits margin of error of 0.8 centimeters.

     4.5 Boundary points and detailed measurement of

    Boundary points and detailed point of a network RTK or total station field survey coordinates. When using RTK with the plan when you first check of the root control point, in line with allowable error requirements, in order to start the measurement. When using Total Station using the analytic intersection, in polar coordinates law approach with measured boundary point, when the station set up, at least one addition to be examined outside the site and post point of view known points in order to ensure the accuracy of the measured . To all the coordinates of boundary points, analytical and analytical side length-based measure of other cadastral, topographical elements of geometry, and based on the draft plan were to review the audit of the relevant data into the cadastral map.

     5 Conclusion

     Control the use of network RTK measurements from the atmosphere, terrain, pass the restrictions depending on conditions, the control measurements easy to operate, highly mobile, working to improve several times more efficient than traditional methods, considerable savings in manpower, not only to achieve full control of cadastral surveying and community locational accuracy requirements and uniform error distribution, there is no error accumulation. Compared to single-base RTK Technically speaking, it is overcome with the radius increases, the accuracy and reliability of the operation to reduce bottlenecks. At the same time also pay attention to the following questions: To ensure the network RTK measurement accuracy, as much as possible to detect a certain number of measurements within and adjacent to the control point Checklist; in control measurements need to do things like extend the measurement time used to select the best observation time, increasing the number of observation methods to improve measurement accuracy; with the precision of the two measurements taken 2 cm below the less suitable.

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[2] Li Zheng, Jin-Song Huang. GPS measurements and data processing. Wuhan: Wuhan University Press, 2007.1

[3] WANG Yong, WU Li-Min. Network RTK technology in city control of the test and measurement study [J], urban survey, 2006 04