Multifrequency Vector Impedance Measurement: Undersampled DFT with Noise Pre-filtering

Multifrequency vector impedance measurement can be used for bio-impedance analysis, and in many other test and measurement applications. Computationally, efficient digital signal processing algorithm for multifrequency vector impedance measurement uses the synchronous under-sampled discrete Fourier transform (DFT). The main practical problem arising from this approach is significantly high noise level, due to aliasing of whole signal spectrum over multiples of under-sampling frequencies. For aliased noise suppression, a solution of digital bandpass pre-filtering of the signals is proposed and analysed on practical examples using MATLAB simulations. The efficiency of the proposed solution is shown