[A brief discussion on the technical characteristics and application status of CORS] Carmelo Anthony’s technical characteristics

CLC classification number: TN96 Document identification code: A Abstract: CORS, with its many advantages, has become the latest technology for GPS applications in China and even around the world and represents its development direction. As a phased development result of GPS technology, CORS has many characteristics such as strong real-time performance, high accuracy, and rapid positioning. This article mainly introduces the application status of the world's representative CORS systems, and classifies them according to their application fields. It summarizes the current application characteristics of the CORS system; the future application directions and fields of the CORS system; and provides ideas for the application and development of the domestic CORS system. .

Keywords: CORS; Application Overview; Technical Characteristics; Existing Problems

1 Introduction

CORS is the Continuous Operation Satellite Positioning Integrated Service System, which is a satellite Positioning technology, computer network technology, digital communication technology and other high-tech multi-faceted and deeply crystallized products are the results of the technological development of the global positioning and navigation system GNSS (that is, what we are familiar with and commonly known as GPS). It is used to solve problems related to positioning, Navigation and meteorological related issues. Its definition is: establishing a local area network consisting of several continuously operating reference stations, data communication links, data centers and user terminals within the research area, comprehensively applying GNSS positioning technology, computer technology, data communication and the Internet (LAN /WAN) technology performs real-time differential correction information calculation, and automatically provides different types of verified GPS observation values ??(carrier phase, pseudo-range), various correction numbers, and Status information, and other systems related to GPS services. CORS technology has been widely used in many aspects such as resource extraction and construction abroad. However, in our country, the application of CORS is in most cases limited to basic levels such as geodetic surveying and urban planning. It can be seen that CORS technology is widely used in highways. The engineering field has very broad prospects. Based on the characteristics of this technology and actual measurement results, this article will look into its three main aspects of surveying, health detection, and automatic control in the field of highway engineering.

2 Overview of the application of global CORS systems

IGS is a successful case of GNSS continuous operation reference station network and integrated service system worldwide. It provides free of charge to global users precise ephemerides and precise satellite clock errors, IGS global tracking station coordinates and their annual change rates, the Earth's rotation rate, and original observation files of all IGS tracking stations; it supports the development of geodesy and geodynamics disciplines It has played a positive role in the field of scientific research and has since been extended to various scientific research fields such as ionospheric research, GPS meteorology, crustal deformation monitoring, Earth rotation parameter solution, and maintenance of the international Earth reference frame. EPN is established by EUREF, the European subcommittee of the IAG Reference Framework. EUREF established the EPN to define, establish and maintain the European reference frame's horizontal datum ETRS89 (European Terrestrial Reference System) and elevation datum EVRS (European Vertical Reference System); and expand its application to areas such as geodynamic research, sea level monitoring and European regions. Weather forecasting and other scientific research fields. The Canadian Spatial Reference System CSRS (Canadian SpatialRef-erence System) is established and maintained by the Canadian Department of National Resources and Geosciences. It provides plane and elevation reference datums and earth orientation parameters for the entire Canadian country. CSRS provides a variety of online services: including online precise single-point positioning services, online precise ephemeris and raw observation data downloads, online coordinate conversion and elevation conversion, etc.

3 Overview of the application of domestic CORS systems

The main domestic projects include China Crustal Movement Observation Network CMONOC, China Coastal Radio Beacon-Differential Positioning System (RBN-DGPS) and other projects, followed by A large-scale infrastructure construction phase has begun in various provinces and cities, and there are mainly two core technologies used, namely VRS and MAC. If divided by these two skills, those who use VRS technology mainly include Shenzhen City, Beijing City, Tianjin, Wuhan, Guangdong City, Guangdong Province, etc.; while those who use MAC technology mainly include Kunming City, Chongqing City, Nanning City, Hong Kong, Macau, Jiangyin, Chengdu, Jiangsu Province, etc.

4 A brief discussion on CORS system technology and characteristics

The current CORS system technology includes virtual reference station technology, regional correction number technology, main and auxiliary station technology, and the other is improved technology, which is Enhanced reference station technology. Each of them has unique characteristics and is supported by different theoretical algorithms.

4.1 VRS (Virtual Reference Station)

It uses the coordinates and real-time observation data of each base station to solve the real-time error model in the area, and then uses a certain mathematical model and flow The rough coordinates of the station are used to simulate the observation data of a virtual reference station adjacent to the rover, and then an observation equation is established to solve the ultra-short baseline between the virtual reference station and the rover.

4.2 FKP (regional correction number)

The FKP (regional correction number) technology estimates the non-difference parameters at each reference station and uses the spatial correlation error model of the non-difference parameters of the reference station. Calculate the correction number of the rover to achieve real-time precise positioning, and its broadcast method is one-way. The difference from VRS is in the final positioning method and error correction method. It also has certain shortcomings, that is, there is a risk of inconsistency in the tropospheric model used by the server and the rover.

4.3 MAC (Main and Auxiliary Station)

MAC (Main and Auxiliary Station) technology means that the rover calculates the space between its own station and each reference station according to a customized space-related error area model. related errors. It is essentially an optimization of the regional correction number (FKP). Compared with the first two technologies, its main features are: (1) Intelligent selection of a sufficient number (at least 3) of reference stations in the network for network solution (VRS only uses 3, FKP uses all reference stations); (2) Reduces the data communication load and improves operating efficiency; (3) It is a real network solution, a standardized network RTK, and the published data format is RTCM3.0.

4.4 ARS (Augmented Reference Station)

It was proposed by Dr. Zhou Letao of Southwest Jiaotong University. The basic idea is to fuse the MRS observation data and transmit the fused data. Differential positioning on the rover realizes multi-baseline solution. It has certain advantages in terms of data processing and data transmission.

5 Problems in Domestic CORS Applications

5.1 Single Target and Sparse Network Networks

Due to the industrialization between various departments, the network construction target is single and failed. Realize all the ideas of this technology in the construction of the national economy. Moreover, due to factors such as the initial investment in network construction, the network construction outlets are relatively sparsely distributed, and blind spots in the work cannot be ruled out.

5.2 Network construction is scattered and lacks overall planning and coordination

At present, network construction in my country is planned and constructed by each province and city, and is jointly constructed by relevant departments of each province and city, such as the Surveying and Mapping Institute, Meteorological Bureau, Transportation Bureau, etc. have limited coverage, lack of overall planning at the national level, and unified, coordinated and parallel implementation.

5.3 Serious insufficient resource sharing

Due to the differences in the construction and program facilities of the CORS systems established by various departments, data sharing problems have become increasingly prominent. Especially between CORS systems across provinces and municipalities, there are differences in data links and transmission methods, as well as data processing technologies. For users and departments, the problem of resource sharing needs to be solved, which is conducive to optimization. The rational use of capital will promote the pace of national economic construction.

5.4 The scope of application services is limited, high investment, and low returns

The initial network construction planning was insufficient, and the scope of services in practical applications was limited, often with high investment and low returns. , its application and promotion are not enough, its application effect in navigation has not been fully exerted, and its important role in the construction of major national projects and national infrastructure has not been fully exerted.

6 Conclusion

From the above content, we can see that through the analysis of the application status of global and domestic CORS systems, there are still many problems in the application of the system in our country. The establishment and operation of the CORS system network should develop in the direction of overall planning, comprehensive goals, balanced regional development, standard implementation, maximum sharing of data, uniform outlets, extensive services, and benefits higher than investment.

References:

[1] Guo Wanli, Zhang Yong, et al., A review of the application of Urban GPS Continuous Operation Reference Station Network (CORS) [J]. People's Pearl River, 2008. (1 ):65-67.

[2] ponents/prods. html

[3] http: //www. ngs. noaa. gov/CORS/links1/