GNSS positioning accuracy index calculation

According to whether there is a reference point （ Truth value ）, There are two calculation methods .

Mode one ： No truth value
No truth value , Then the calculation is the internal coincidence accuracy —— Positioning deviation （position deviation）;
Because there is no external reference , Therefore, the average value should be used for data analysis center.
The most important thing is to change the coordinate system into ENU, Again according to deviation Formula of , It is divided into 2D and 3D In the form of .

Mode two ： True value
True value , Explain that there are external references , It is necessary to calculate center From the average value to the true value point . At this point, you can calculate CEP50,CEP95,RMS Three indicators ;
1、CEP50 and CEP95
stay BLH In a coordinate system , Among them, we need to use the knowledge of geodesic , Sort the calculated distance , take 50% or 95% that will do .
2、RMS
In the plane , stay ENU Calculate in the coordinate system ; On elevation , stay BLH Coordinate system .