Accuracy assessment and improvement for level survey using real time kinematic (RTK) GPS

The Global Positioning System (GPS) is a satellite based positioning and navigation system that provides precise position, velocity and time information. The height accuracy in GPS is lower than the planimetric accuracy. This paper discusses about the height accuracy achievable in real time kinematic mode using single frequency GPS with Novatel's RT20 algorithm. Analysis was also done to see whether there is any correlation between the antenna velocity (speed) and the accuracy. As a core part of the research, a procedural was developed to improve the height accuracy based on the observed data in RTK mode. This was accomplished by using two calibration points as reference and distributing the errors among the observed points. This improved the accuracy to a few centimeters level (2-4 cm, RMS), which is a very significant improvement.