METHOD AND APPARATUS FOR DIGITAL DEMODULATION AND FURTHER PROCESSING OF SIGNALS OBTAINED IN THE MEASUREMENT OF ELECTRICAL BIOIMPEDANCE OR BIOADMITTANCE IN AN OBJECT
Methods and apparatus for digital demodulation of signals obtained in the measurement of electrical bioimpedance or bioadmittance of an object. One example comprises: generating an excitation signal of known frequency content； applying the excitation signal to the object； sensing a response signal of the object； sampling and digitizing the response signal to acquire a digitized response signal representing the response signal with respect to frequency content, amplitude and phase； correlating, for each frequency fAC of the excitation signal applied, digitized samples of the response signal, with discrete values representing the excitation signal； calculating, using the correlated signals for each frequency fAC of the excitation signal applied, complex values for the bioimpedance Z(fAC)； providing, over time, a set of digital bioimpedance waveforms Z(fAC,t))； separating the base bioimpedance Z0(fAC), from the waveforms； and separating the changes of bioimpedance ΔZ(fAC,t), from the waveforms.
