Patent ID: 6915240

Claim:
A method for determining an exponential decay rate of a signal in the presence of noise, said method comprising: receiving an exponentially decaying signal from a detector; digitizing said signal to form a first array of data points; estimating a baseline value of said signal by averaging a final fraction of said data points; subtracting said baseline value from said first array to generate a second array; identifying a last data point on said second array occurring before a negative or nil valued data point on said second array; scaling an ordinate value of said last data point by a factor greater than unity to determine a new first data point for a baseline fit on said first array; fitting remaining data on said first array to a straight line to determine an estimate for a sloping baseline and said noise; subtracting said straight line from said data points to establish a resulting array; identifying a last data point on said resulting array occurring before a negative or nil valued data point on said resulting array; performing a logarithmic transformation of said resulting array up to said last data point on said resulting array; and determining said decay rate of said signal; wherein said noise includes broadband noise and excess low frequency noise and wherein said low frequency noise has spectral components having a period greater than four times a record length.