GNSS positioning accuracy units CEP, RMS, 2D RMS In GNSS products, manufacturers provide several accuracy parameters: CEP, RMS. The meaning of these accuracy parameters will be described in detail below: CEP and RMS are the positioning accuracy units of GNSS. Units of probability. Let’s take 5M CEP, which means that a circle is drawn with a radius of 5M, and 50% of the points can be drawn within the circle. That is to say, the probability of GNSS positioning at 5M accuracy is 50%, and the corresponding RMS (66.7%) 2DRMS (95%) Of course, many businesses are willing to give CEP, because the unit is bigger, the number in front is smaller, it looks good. The horizontal accuracy is the circular probability error (CEP) which means that 50% of the results are within the given circle diameter and 50% of the results are outside the circle.
The RMS is 1 sigma or 1 standard deviation. If the result is unbiased, the probability is 67%. 2dRMS is 2 sigma or 2 times the standard deviation, the probability is 95%. Their mutual conversion can follow the following rules: CEP multiplied by 1.2 can be converted to RMS, CEP multiplied by 2.4 can be converted to 2d RMS.
