Patent ID: 7133791

Claim:
A method for two-mean estimating level-crossing time intervals and signal frequencies, comprising the steps of: collecting a plurality of time difference samples from a signal g(x), said plurality of time difference samples further comprising N=2p+1 number of consecutive time samples x(k), x(k−1), . . . x(k−2p−1), where said p=1,2 . . . and is a positive integer, and a plurality of noises; generating a time sequence input for a means for filtering from said plurality of time difference samples; calculating a time interval estimate output in said filtering means, said filtering means having 2p+1 number of shift registers, a group of adders and a set of coefficients {−1, −1, . . . , 1, 1}, said time interval estimate output having the formula: z ⁡ ( k , k - 2 ⁢ p - 1 ) = 1 ( p + 1 ) 2 ⁢ ∑ j = 0 2 ⁢ p + 1 ⁢ ⁢ α ⁡ ( j ) ⁢ x ⁡ ( k - j ) calculating an N-sample level crossing time interval having the formula: z ⁡ ( k , k - 2 ⁢ p - 1 ) = 1 ( p + 1 ) 2 ⁡ [ ∑ i = 0 p ⁢ ⁢ x ⁡ ( k - i ) - ∑ i = 0 p ⁢ ⁢ x ⁡ ( k - i - p - 1 ) ] providing a plurality of shift register outputs from said shift registers to said adders; generating an increased accuracy N-sample level-crossing time interval estimate from estimating said N-sample level crossing time interval by two mean values, ∑ i = 0 p ⁢ ⁢ x ⁡ ( k - i ) ⁢ ⁢ and ⁢ ⁢ ∑ i = 0 p ⁢ ⁢ x ⁡ ( k - i - p - 1 ) , and averaging out said plurality of electronic noises; and sending a filtered output to an amplifier, said filtered output including said increased accuracy N-sample level-crossing time interval estimate; calibrating and gain adjusting said filtered output; and providing an average time difference z(k,k−2p−1) and an estimated level-crossing time interval output from said increased accuracy N-sample level-crossing time interval estimate.