Application of RTK and network RTK

(A) the basic principles of RTK and network RTK

Conventional GPS measurement methods, such as static, fast static and dynamic measurement, need to be solved afterwards to obtain centimeter-level accuracy, while R TK is a measurement method that can obtain centimeter-level positioning accuracy in real time in the field. It adopts carrier phase dynamic real-time difference method, which is a major milestone in GPS application. Its appearance provides convenience for various control surveys such as engineering lofting and field verification of mining rights, and 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 collects GPS observation data, but also receives reference station data through data link, and forms differential observation values in the system for real-time processing, giving centimeter-level positioning results, which takes no more than one second. The mobile station can be stationary or moving; It can be initialized at a fixed point before entering dynamic operation, or it can be started directly under dynamic conditions to complete the search and solution of weekly ambiguity in dynamic environment. After solving the known number for the whole weekend, the real-time processing of each epoch can be carried out. As long as the tracking of the phase observations of more than four satellites and the necessary geometric figures can be maintained, the mobile station can give centimeter-level positioning results at any time.

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. R TK can be used after establishing its own control network, while network RTK does not need to establish its own control network.

Network R TK integrates GPS, wireless communication, computer technology and network management, and is showing great advantages in surveying and mapping technology. The whole system consists of several GPS CORS and a control center. The cost of a CORS station is about 500 thousand, and a provincial system is generally composed of 40 ~ 70 base stations. The whole network system consists of five parts: fixed reference station system, network control center, data transmission system, data transmission and broadcasting system and user system. The fixed reference station is responsible for collecting satellite data and transmitting it to the control center. The data link between the reference station and the control station can be through optical cable, Internet or ordinary telephone line; The control center consists of VR S (Virtual Reference Station) virtual reference station management software, computer and communication system. It receives data from a fixed reference station and rough coordinates from the user. According to the user's position, the computer calculates a set of optimal data, corrects satellite orbit errors, errors caused by ionosphere, troposphere and atmospheric refraction, and transmits high-precision differential signals to users, which is equivalent to establishing a virtual reference station dozens of meters near the mobile station (user), solving the problem of traditional RTK working distance and enabling users to obtain stable centimeter-level accuracy measurement results.

Compared with traditional RTK, network RTK has obvious advantages. Double-star system (GPS+GLO NASS dual-system navigation and positioning) is a hot spot in the development of GPS RTK, which can receive about 14 ~ 20 satellites, which is incomparable to conventional RTK. This technology enables GPS equipment to achieve centimeter-level accuracy in the shortest time, and has the strongest anti-interference and shielding ability. Virtual reference station improves the quality and distance of RTK positioning, enhances the reliability of RTK and reduces the initialization time. VRS technology can make the position accuracy of RTK positioning plane 1 ~ 2cm around 50km without establishing its own reference station. Traditional R TK must establish its own reference station every time, and network RTK avoids the errors caused by uneven precision and repeated station setting. Economically save manpower and material resources, as long as you register with the management department and pay the fees, you can get ideal results at any time.

(B) the application of network knowledge

In this field verification of mining rights, for the survey area that can receive GPS job site signals for a long time, the control point information is obtained directly through fast static positioning and network R TK without ground control survey. In areas with network R TK, network R TK system can be used first to improve work efficiency.

The precondition of using network R TK is that there is a recognized network R TK reference station in the survey area, and the receiver can continuously and stably receive good satellite signals and network signals. Data conversion is handled by the network RTK management department.

See appendix g for the recording format used by network R TK.

It is generally stipulated that the network R TK cannot be used as a control point. According to the accuracy requirements of field verification of mining rights, control points are allowed to be introduced into the mining area. Calibration difference refers to the result that the average value of several measurements of a known point is worse than that of a known point.