A method to calibrate a transducer, whereby the transducer provides a first
signal, and whereby a reference provides a reference signal. The first
signal is sampled at a sampling rate comprising a reference frequency, and
a digital measured first signal waveform is formed. The reference signal
is sampled at the sampling rate, and a digital measured reference signal
waveform is formed. The real and imaginary components of the measured
first signal waveform are determined at (P) harmonics of the reference
frequency. A filtered first signal waveform is formed using those real and
imaginary components. The real and imaginary components of the measured
reference signal waveform are determined at (P) harmonics of the reference
frequency. A filtered reference signal waveform is formed using those real
and imaginary components. A transfer function is formed using the filtered
first signal waveform and the filtered reference signal waveform. A
calibration curve is formed using that transfer function.
