Patent ID: 8514127

Claim:
A method of calculating low probability events for evaluation of precision performance of a satellite navigation system comprising a space segment transmitting radiolocation signals to a receiver segment, comprising the steps: measuring, with a system, an estimated error of location of a receiver of the system for a plurality of samples and calculating a maximum location error threshold, being a protection radius, that can be guaranteed by the system for said samples, the estimated error and the protection radius being defined in a dimension of a position frame of reference, calculating, with the system, a first proportion of a distribution of samples satisfying the conditions: i. the protection radius being less than an alert threshold, ii. a quotient of the protection radius and of the estimated location error being greater than a safety quotient, the safety quotient being the ratio of the alert threshold to a level of requirement of estimated error, calculating, with the system, a second proportion of the distribution of samples satisfying the conditions: iii. the protection radius being less than the alert threshold, iv. the quotient of the protection radius and of the estimated location error being less than the safety quotient, v. the estimated location error being less than the level of requirement of estimated error, modelling, with the system, at least one component of the distribution of samples, the component representing the samples of low probability of occurrence of the distribution and the modelling being calculated by applying the theory of extreme values on the basis of observed samples of the distribution.