Patent ID: 8335948

Claim:
A method comprising: repeatedly comparing an input signal with a first number of thresholds to obtain a value at each comparison, each value belonging to a value range comprising a second number of different possible values, said second number being equal to said first number plus one; counting the number (f b ) of equal values during a period of time thereby obtaining said second number of counts; comparing said counts with a count threshold, the counts exceeding said count threshold being defined as reliable counts, and the counts lower than or equal to said count threshold being defined as unreliable counts; determining an order for use in an extrapolating function for extrapolating a probability density function in a tail region by: calculating a next unreliable count using a lower and a higher value for a determined order to obtain a next first unreliable count for said lower value of said order and a next second unreliable count for said higher value of said order, wherein an order of said extrapolating function is considered equal to said lower value, if said next first and second unreliable counts differ less than or equal to a count difference.