RTK common operation problems and solutions, full of dry goods, quick collection!
Causes and solutions of elevation mismatch of plane coordinates of RTK calculation parameters
Reason 1: The input of the rod height of the control point is wrong.
Solution: When calculating the conversion parameters again and measuring the control points in new projects, it is necessary to carefully check whether the actual height of the centering rod is consistent with the height of the rod entered when saving the points.
Reason 2: The elevation input of control points is wrong when calculating parameters.
Solution: Re-create the project calculation conversion parameters. When adding the calculation parameters of control points, carefully check the coordinate elevation of control points to avoid input errors.
Reason 3: Abnormal elevation change (key! ! ! ! )
Solution: First, create a new project, then recalculate the conversion parameters, calculate the plane fitting parameters with three control points, or calculate the surface fitting parameters with six control points.
Why do you need to calculate the "regional" local parameters?
We know that the geodetic coordinates of WGS84 provided by GPS are of little significance in most engineering applications. Actually, it is necessary to convert the 84 coordinates observed by GPS into national plane coordinates (such as BJ54) or engineering construction coordinates. For the conversion from WGS84 to BJ54, we can use Gaussian projection method. At this time, we need to determine the conversion parameters (three parameters or seven parameters) between WGS84 and BJ54 geodetic datum, and define the offset, rotation angle and scale difference of the three-dimensional rectangular coordinate axis. Only with the "regional" coordinate transformation parameters of the survey area can we obtain the grid coordinates we need in real time by RTK survey, because with the transformation parameters, the geodetic coordinates observed by GPS can be transformed into local coordinates.
When two different rectangular coordinate systems are transformed, the accuracy of coordinate transformation depends not only on the mathematical model of coordinate transformation and the coordinate accuracy of common points for solving transformation parameters, but also on the number of common points and geometric structure. In view of the fact that there may be some systematic errors in the ground network, which are not exactly the same in different areas, the accuracy of coordinate transformation can be improved by using partition transformation parameters and partition coordinate transformation.
If there is no known point, you want to test the accuracy of GPS equipment.
In this case, in the case of a fixed solution:
1, measure the coordinates of two points, and then use a steel rule to measure whether the relative position is accurate.
2, the same point repeated measurement for many times, see the coordinate difference (within the accuracy).
3. Distance measurement with total station and back calculation with GPS points.
When we use RTK to measure and use known points as reference stations (plane coordinates), after all the settings are completed, the reference and mobile LINK lights flash normally, but the manual always shows single point positioning. When we use unknown points to build stations, we can quickly get a fixed solution! Why?
Reasons: 1. The input coordinates of known points are wrong (wrong input, or wrong coordinates provided by users), and the difference should be less than one second by comparing the automatically obtained geodetic coordinates with the WGS-84 geodetic coordinates provided by users (users provided the adjusted ones, and automatically obtained the single-point positioning, with an accuracy of meters, so there is a deviation).
2. Before determining the conversion parameters from 84 coordinates to the plane coordinates used by users, the notebook software only supports the input of WGS84BLH coordinates.
What is the difference between the functions of three parameters, four parameters and seven parameters? How to use it?
Strictly speaking, the coordinate transformation between two ellipsoids needs seven parameters, such as WGS84 and BJ54, WGS84 and XIAN80. There is no uniform set of parameters for the transformation between them, so it should be calculated according to some common points in the region. Three parameters is a special case of seven parameters, which only considers the translation in three directions between two ellipsoids. Four parameters are needed to convert in different plane coordinate systems of the same ellipsoid, such as BJ54 and BJ63 coordinate systems, Beijing 54 and Shenzhen coordinate systems, etc. Of course, it is also feasible to apply four parameters to transform two plane coordinates after different ellipsoid projections. At least one point is used to calculate three parameters, two points are used for four parameters and three points are used for seven parameters.
Failed to get access point/source list.
First, check the settings of the mobile station (whether it is set to the network mode of the mobile station), then check whether the parameters (IP ports) are set correctly. If they are all set correctly, finally check whether it is caused by network reasons, and check whether the SIM card is plugged in properly or whether the SIM card is in arrears. If you are connecting to a wifi hotspot, check whether the wifi hotspot can connect to the network normally (it is recommended to open a webpage for testing), or replace it with another wifi hotspot.
Base stations and mobile stations are often disconnected when in use.
Solution: 1. First, confirm how the peripheral signals are, or use 4G or 3G cards.
2. Change the difference format to RTCM3.0 and double star.
3. Change the cut-off angle
4. Check whether the firmware version has been successfully upgraded.
5, signal strength from the data link state
6, mobile phone card problem, some mobile phone cards can be boarded when they are in arrears, but they cannot transmit differential signals.
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