Near-binary multisine design with arbitrary sparse spectrum for fast BIS measurement

Bioimpedance spectroscopy (BIS) measurement is widely used in various biological medical applications. Broadband excitation signals with sparse spectra can be beneficial to increasing the signal-to-noise ratio (SNR) and decreasing the time of BIS measurements. This study introduces a rapid synthesis method to generate near-binary multisines (NBMs) with arbitrary sparse spectra that have the advantage of lower crest factor and less aliasing compared with the traditional multisines or binary signals. One of the NBM examples, abbreviated as Quasi-Log-Flat-19, which contains 19 quasi-logarithmical and flat desired components from 1 kHz to 1 MHz is used as the voltage source or the current source for BIS measurements (only 1 ms required). The results show that the impedance SNR by using Quasi-Log-Flat-19 (68.9 dB in average from the voltage source and 63.5 dB in average from the current source) is always higher in comparison of the corresponding optimised multisine with the same desired spectrum (65.1 dB in average from the voltage source and 58.5 dB in average from the current source). It can be concluded that NBMs can be used as good alternatives to traditional optimised multisines with sparse spectrum distribution in fast BIS measurement.