The reference station is built at a known point or an unknown point;
Satellite signals received by reference stations are sent to users in real time through wireless communication networks;
The user receiver calculates the received satellite signal and the reference station signal in real time to obtain the coordinate increment (baseline vector) between the reference station and the rover station.
The following is a detailed introduction of RTK:
RTK, which sends the carrier phase collected by the reference station to the user receiver for differential and coordinate calculation. In GPS survey, such as static, fast static and dynamic survey, centimeter-level accuracy can be obtained only after solving, and RTK (real-time differential positioning) is a measurement method that can obtain centimeter-level positioning accuracy in real time in the field, and its appearance greatly improves the efficiency of field work.
High-precision GPS measurement must adopt carrier phase observation. RTK positioning technology is a real-time dynamic positioning technology based on carrier phase observation, which can provide the three-dimensional positioning results of the station in the specified coordinate system in real time and achieve centimeter-level accuracy. In RTK working mode, the reference station transmits its observation values and station coordinate information to the rover station through the data link.
The mobile station not only receives data from the reference station through data link, but also collects GPS observation data, and forms differential observation values in the system for real-time processing, giving centimeter-level positioning results, which lasts less than one second. The mobile station can be stationary or moving; It can be initialized at a fixed point before dynamic operation, or it can be started directly under dynamic conditions to complete the search and solution of integer ambiguity in dynamic environment.
After the unknown solution of the whole period is fixed, the real-time processing of each epoch can be carried out. As long as the phase observations of more than four satellites can be tracked and the necessary geometric figures can be maintained, the mobile station can give centimeter-level positioning results at any time.
Extended data:
RTKLIB is an open source software package developed by Tokyo Ocean University in Japan, which is used for the application of standard and accurate GNSS global navigation satellite system. RTKLIB includes a portable program library and several application program (AP) libraries.
Characteristics of RTKLIB:
(1) supports standard precise positioning algorithms: GPS, GLONASS, QZSS quasi-zenith satellite system, Beidou and SBAS.
(2) Support multiple positioning modes and GNSS real-time and post-processing: single point, DGPS/DGNSS, dynamic, static, moving baseline, fixed point, PPP motion, PPP static and PPP fixed point.
(3) GNSS supporting various standard formats and protocols:
RINEX？ 2. 10，2. 1 1，2. 12 OBS /NAV/ GNAV / HNAV，RINEX 3.00 OBS / NAV，RINEX 3.00CLK，RTCM？ V.2.3，V.3. 1 RTCM 1.0，RTCA NTRIP/NMEA DO-229 c？ 0 183, SP3-C, IONEX 1.0, ANTEX 1.3, NGPCV and EMS 2.0.
Key technologies:
The key of RTK technology lies in data processing technology and data transmission technology. RTK positioning needs the reference station receiver to transmit observation data (pseudo-range observation and phase observation) and known data to the rover receiver in real time. The amount of data is relatively large, which generally requires a baud rate of 9600, so it is not difficult to realize it in a radio station.
With the continuous development of science and technology, RTK technology has developed from the traditional 1+ 1 or 1+2 to WADGPS, and CORS systems have been established in some cities, greatly improving the measurement range of RTK. Of course, great progress has been made in data transmission. Wireless transmission has developed to GPRS and GSM networks, which greatly improves the efficiency and scope of data transmission. In terms of instruments, it is not only high in accuracy, but also simpler and easier to operate than traditional RTK.
Success stories:
RTK helps Anhui power transmission project to the east;
20 13 16 CCTV news broadcast reported that with the last conductor crossing the Huaihe River in place, "Anhui Power Transmission to the East" was carried out from Huainan to Shanghai. [1] The main project of crossing the Huaihe River in UHV power transmission and transformation project has been completed. The Anhui Power Transmission Project, which adopts the world's top UHV transmission technology, successfully completed the construction of crossing the Huaihe River at an altitude of nearly 200 meters today, once again achieving a historic breakthrough in China power grid construction.
Anhui East Transmission 1 1,000 kV UHV transmission line starts from Huainan, Anhui, passes through Zhejiang and Jiangsu, and reaches Shanghai, with a total length of 656 kilometers. At present, it is a double-circuit transmission line on the same tower with the highest voltage level and the largest transmission capacity in the world, with a total investment of 186 billion yuan, and it is planned to be put into operation at the end of this year.
UHV refers to the voltage levels of AC 1000 kV and above and DC±800 kV and above. Compared with general transmission lines, UHV has the advantages of large transmission capacity, long transmission distance and low power consumption. But at the same time, its technical difficulty and high demand for equipment are unprecedented. In the 1960s and 1990s, the former Soviet Union, the United States, Japan, Italy and other countries conducted preliminary research on UHV AC transmission, but failed to form mature technology and equipment. In China, not only has it made a comprehensive breakthrough in theoretical innovation, technical research and engineering practice of UHV, but it has also become the first and only country in the world to successfully master and actually apply this cutting-edge technology.
Taking G970 RTK equipment undertaking the project of "Anhui Power Transmission to the East" as an example, it applies high-precision GIS acquisition and measurement technology, and with its precise GPS positioning function, centimeter-level acquisition accuracy, real-time data interaction and high stability, it can play a role in power survey, design, construction and lofting, providing accurate data sources for design, construction and decision makers, and providing reliable basis for information construction and management of power system.
At present, there are three UHV transmission lines that have been built and commercialized in China, including "Anhui Power Transmission to the East" and three UHV lines under construction. According to the plan, China will build a smart grid covering the whole country on the basis of UHV backbone network to further alleviate the contradiction between energy distribution and use.
References:? RTK- Baidu encyclopedia? RTK survey-Baidu encyclopedia