CORS system consists of five parts: reference station network, data processing center, data transmission system, positioning and navigation data broadcasting system and user application system. Each reference station and monitoring and analysis center are connected into a whole through a data transmission system to form a private network.
Reference station network: The reference station network consists of reference stations evenly distributed in the range. Responsible for collecting GPS satellite observation data and transmitting them to the data processing center to provide system integrity monitoring services.
Data processing center: the control center of the system, which is used to receive the data of each reference station, process the data, form multi-reference station differential positioning user data, form a data file with a certain format, and distribute it to users. Data processing center is the core unit of CORS and the key to realize high-precision real-time dynamic positioning. According to the real-time observation data collected by each reference station, the center continuously models and calculates the whole area for 24 hours, automatically generates virtual reference stations corresponding to the position of the mobile station (including reference station coordinates and GPS observation information), and provides code phase/carrier phase differential correction information to various users who need to measure and navigate in an international common format through the existing data communication network and wireless data broadcasting network, so as to calculate the accurate position of the mobile station in real time.
Data transmission system: the data of each reference station is transmitted to the monitoring and analysis center through optical fiber dedicated line. The system includes data transmission hardware equipment and software control module.
Data broadcasting system: The system broadcasts positioning and navigation data to users through mobile networks, UHF radio stations and the Internet.
User application system: including user information receiving system, network RTK positioning system, post-event and fast precise positioning system, autonomous navigation system and monitoring positioning system. According to the different application precision, the user service subsystem can be divided into millimeter user system, centimeter user system, decimeter user system, meter user system and so on. According to different user applications, it can be divided into surveying and mapping and engineering users (centimeter and decimeter level), vehicle navigation and positioning users (meter level), high-precision users (post-processing), meteorological users and so on.
CORS system has completely changed the traditional RTK survey operation mode, and its main advantages are: 1) it has improved the initialization time and expanded the effective working range; 2) By using the continuous base station, users can observe at any time, which is convenient to use and improves work efficiency; 3) Having a perfect data monitoring system can effectively eliminate system errors and cycle slips and enhance the reliability of differential operation; 4) Users don't need to set up a reference station, thus realizing stand-alone operation and reducing the cost; 5) Adopt a fixed and reliable data link communication mode to reduce noise interference; 6) Providing remote Internet service to realize data sharing; 7) Expanding the application range of GPS in the dynamic field, which is more conducive to the accurate navigation of vehicles, planes and ships; 8) It provides new opportunities for building a digital city.
CORS system is not only a dynamic and continuous positioning frame benchmark, but also an important urban infrastructure to quickly and accurately obtain spatial data and geographical elements. CORS can provide high-precision, high-reliability and real-time positioning information to a large number of urban users at the same time, realize the complete unification of urban surveying and mapping data, and will have a far-reaching impact on the collection and application system of modern urban basic geographic information systems. It can not only establish and maintain the benchmark framework of urban surveying and mapping, but also provide high-precision spatio-temporal information in a fully automatic, all-weather and real-time manner, and become the basis of regional planning, management and decision-making. The system can also provide differential positioning information, open up new applications of traffic navigation, and provide high-precision, high spatial-temporal resolution, all-weather, near-real-time and continuous water vapor change sequences, thus gradually forming a regional disastrous weather monitoring and forecasting system. In addition, CORS system can be used for high-precision time synchronization between communication system and power system, and can provide monitoring and forecasting services for land subsidence, geological disasters and earthquakes. And study and discuss the temporal and spatial evolution process of disasters.
CORS can be defined as one or several fixed and continuously running GPS reference stations, which use the network composed of modern computer, data communication and Internet (LAN/WAN) technology to automatically provide different types of GPS observations (carrier phase, pseudorange), various corrections, status information and other related GPS services to users of different types, needs and levels in real time.