Overview
The Yellow River is China's second largest river in the meaning of his very important, the same harm his people two thousand years is very worried, which is why the Yellow River in China every year, invested heavily to govern; however, rapid changes in the surrounding environment of the Yellow River is that we input is constantly increasing, how can we track and monitor the water conservancy project management and construction play a real role has become our most pressing problems. Water survey is the same as a very important task, but also very strict, he derived the accuracy and correctness of the data will have a direct impact on the targets of the whole project. Usually we order to calculate the flood discharge and dredging out the river channel capacity, the need for vertical and horizontal cross-section of the river measured to arrive at the reliability of the data we need. For the conventional channel cross-section measurements we often use intersection, sight distance law and the law slant range measurement, depth measurement is mainly sounding rod method, ultrasonic echo detection method, etc., but with the development of technology GPS-RTK technology continues to mature, and the Huanghe River water and the surrounding environment, the changing, conventional methods can not fully meet our demand for real-time information on the Yellow River, which prompts us to continuously explore new ways to use existing technology and equipment to search for more big breakthrough. GPS-RTK for us, no longer an alien concept, and the use of RTK technology and digital detector and the depth of the river cross-section measurement is regarded as a good attempt.

RTK technology constitutes a
RTK technology, the main reason for the promotion so fast, or its technical and precision is reflected in other technologies can not match its dynamic real-time measurement method is more rapid technological catch up to other makes. RTK (Real Time Kinematic) positioning which is based on real-time carrier phase differential settlement of a technology, it needs to solution in a shorter period of time was calculated ambiguity values, the dynamics solver Ambiguity There are two common methods Species: ambiguity function method, least-squares search method, which can achieve centimeter-level accuracy. Use of RTK can be used simultaneously to measure two or more GPS receivers usually have a GPS receiver mounted on a known control point, I dream often referred to as base stations; In addition several of the terrain in real time as a mobile station measurements. Base stations and mobile stations are a group of satellite observations, the base station will observe the data connected by data sent to the mobile stations, mobile stations that the observed data and the data itself is bad decomposition operator, which are mobile stations, and between the base station with high precision relative position of the mobile station will eventually calculate the solution of the three-dimensional data storage and transfer them to complete the dynamic observation.
The use of RTK for dynamic real-time measurement time to note the following issues:
A first base station will be set up in an open place, to avoid any obstructions blocking the satellite signal, so that it always can be quickly fixed, stable reference station at the top of the number of stable star at work. The second is to give full consideration to whether the surrounding electromagnetic interference, the base stand and the difference between the targeted mobile station when the Solution is the commonly used radio signals, if the electromagnetic field around the gun will lead to the stability of the data signal transmission, and therefore make our work efficiency has been greatly reduced, RTK there can be no advantage of playing, so power lines, water, radio transmission towers, high-power motors are not suitable for erecting around the GPS base station.
2 pairs of GPS hand-book set of parameters, including a reference to prop up the ball, using the coordinate system, the central meridian, projection models, and a known point data, radio frequency, etc., should be used on your system and to be carried out by full understanding of the task, the only way the process of conducting the tests, in order to ensure that the entire system to work properly.
3 Strictly speaking, RTK is also a need to verify the data, but a stable set of GPS systems are usually very stable, we recommend the use of Trimble GPS, but the data output can also be a time when the raw data for testing.

RTK in the Yellow River section measurement
As the Yellow River and is surrounded by a wider complex geological conditions, so we choose to cross the river laid a number of fourth-grade GPS static control points, all of the GPS control points of the site must comply with the RTK base station measurements election so request, the away from interference. The same time, four control points such as GPS elevation measurements we use the standard geometry, so for us to directly use the base station data, to reduce unnecessary trouble. We first use of the hands of the existing topographic map of the location of the Yellow River to the preliminary design section, and then buried in the ground reconnaissance election marked stone, laid two sections a day cross-section basis points, respectively, are not located in the two ends of the Yellow River levee, and then complete the point plane coordinates, and elevation measurements. 2 basis points for each cross-section of the three-dimensional coordinates entered into the computer, in the professional software to complete the section of route with the help of the orientation of work, each section of cloth route.
Outside the data collection must also ensure that mobile stations and digital depth sounder in the same plane coordinates, so that collected in order to ensure that no deformation of the three-dimensional coordinates, while for the sampling interval is also necessary to keep pace. Acquisition process, we need real-time monitoring of sample verification to ensure data accuracy and correctness. Finally, the ultimate collection of data entered into a computer for data processing, processing should take full account of water depth, flow speed and suspended solids in water such objective unavoidable factors. Usually sudden jumps of data we can analyze ourselves, if we carefully analyze each and every section, we can remove most of the pseudo-data. However, the data for the various phenomena of false-leg we have the door to conduct a rigorous analysis, if necessary, we will provide timely tested additionally. When all the data through validation, it will use the final data mapping software to establish a more professional image of the data that we have seen the results - cross-section diagram, and as a final product available to the demand side.
Summary
RTK technology through cross-section of the Yellow River in the practice of Surveying Engineering, discusses the technical features of RTK measurement, for measuring cross-section of the Yellow River and digital sounder RTK we use should be said that relatively successful, both in the accuracy of the data or on its aging Upper is a very suitable, although sometimes RTK measurements unstable situation, but as long as we care to ensure that RTK in a good work environment, I believe that would be avoided.



References:
DGPS RTK technology in the channel measurement ZHOU Feng-nian of modern surveying and mapping
RTK technology in the river cross-section measurement Liu Yanxiang waterway port
GPS RTK positioning technology in the measurement of the Yellow River in Shandong Water Conservancy LIU ZHENG