The selection of coordinate parameters has a great influence on the measured results. The GPS uses the WGS-84 coordinate system, and the umbrella calculations are performed in this coordinate system. The first results after processing are WGS-84 coordinates. However, what the user needs is the national grid coordinates or local coordinates. Only the independent coordinate system of Taiyuan GPS was used for this measurement, and then it was projected onto the Gaussian plane. Therefore, the accuracy of coordinate conversion is also a very important issue. In actual operations, the conversion parameters are selected using known common points. Its accuracy is not only related to the position and number of selected points, but also closely related to the coordinate accuracy of the selected points. When selecting common points, you should select known points within the survey area.
The influencing factors of the GPS system itself include the number of GPS satellites, satellite graphics, and atmospheric conditions. For this reason, the ephemeris forecasting operation should be done well. When satellite conditions are not good, some auxiliary operations (such as base station handling) should be performed.
Strict and standardized operation to reduce the influence of human factors on measurement accuracy. RTK practice has proved that the professional level and experience of the observer has a great impact on the accuracy and reliability of the effect. Any errors in centering errors, measuring antenna heights, or inputting reference station coordinates will affect all measured coordinates. It is necessary for the observer to hold the rod straight so that it is located on the plumb line of the measurement point for control measurement. It is recommended that the tripod base be centered and leveled. The observer should also carefully check the RTK equipment, the level on the tripod base and the rover rod. It is necessary to check and correct in order to eliminate the effect of any system error on the observed value.
In order to eliminate occasional noise and improve the accuracy and reliability of RT K measurement, it is necessary to add the number of epochs observed and repeat the measurement.
If you want to choose RTK elevation, it is necessary to do:
When calculating the conversion parameters, there must be a certain number of control points on the periphery of the measurement area to measure the fourth-level level in parallel. The selected common point should not be too far away from the measurement area and be evenly distributed in the measurement area. Observe to measure its gross error, and perform a certain number of known point inspections.