Patent ID: 7593815

Claim:
A method for improving the signal-to-noise ratio of a signal S(t), S(t) containing Signal and noise, the method comprising: (a) obtaining a measurement of S(t) at a frequency-of-interest; (b) obtaining noise measurements of S(t) at one or more noise frequencies where the Signal portion of S(t) is expected to be small; (c) estimating the noise at the frequency-of-interest using the noise measurements at the one or more noise frequencies, wherein estimating the noise at the frequency-of-interest, N(T), comprises: minimizing ⁢ ⁢ ∑ T ∈ { T 1 , T 2 } ⁢ ⁢  S ⁡ ( T ) - N ⁡ ( T )  2 ⁢ ⁢ where ⁢ ⁢ N ⁡ ( T ) = c 1 ⁢ n 1 ⁡ ( T ) + c 2 ⁢ n 2 ⁡ ( T ) + c 3 ⁢ n 3 ⁡ ( T ) + … ⁢ ; ⁢ and; where c 1 , c 2 , c 3 , . . . are complex coefficients; n 1 , n 2 , n 3 , . . . are the measurements of noise at the noise frequencies; and T 1 and T 2 define a time period when little or no Signal is present in S(t); and (d) subtracting the estimated noise from the measurement of S(t) at the frequency-of-interest.