circular error probable (sat com) (CEP)
Circular Error Probable(CEP) is the scatter radius with which the position accuracy of navigation devices is specified. The CEP value is a probability value. It is given as a percentage and refers to the radius of a circular area whose center is determined by the GPS system.
The most commonly used CEP values are the 50% value R50, the 67% value R67, and the 95% value R95. For example, if the displayed CEP value is 50% for a radius of 5 m, then this means that half of all measurement results are within this radius of 5 m, but also half of the measurement values are outside. Furthermore, it is the case that 95 % of all measurement points are located in a circle with a radius twice as large, which would correspond to 10 m.
The location accuracy of the CEP value can be improved by combining it with other navigation systems.