Patent ID: 7299146

Claim:
A method to calibrate a transducer receiving an input signal and generating an output signal, comprising the steps of: providing an input signal to said transducer; generating an output signal by said transducer, wherein said output signal comprises noise; establishing a sampling rate comprising a reference frequency; sampling said input signal at said sampling rate; sampling said output signal at said sampling rate; forming a measured input signal waveform; forming a measured output signal waveform; determining at (P) harmonics of said reference frequency the real components and the imaginary components of said measured input signal waveform; forming a filtered input signal waveform; determining at (P) harmonics of said reference frequency the real components and imaginary components of said measured output signal waveform; forming a filtered output signal waveform; calculating a transfer function comprising a mathematical relationship between said filtered output signal waveform and said filtered input signal waveform; forming a calibration curve using said transfer function, wherein said calibration curve comprises a relationship between said input signal and said output signal minus said noise; calibrating said transducer.