Design of tri-level excitation signals for broadband bioimpedance spectroscopy.
Bioimpedance spectroscopy (BIS) measurement methods have been evolving from the traditional frequency-sweep approach to the multi-frequency simultaneous measurement technique which can drastically reduce measuring time and will be increasingly attractive for time-varying biological applications. Multi-frequency mixed (MFM) signals with sparsely distributed spectra are desirable for broadband BIS measurement. This paper proposes a synthesis method to design a series of tri-level MFM signals which contain only three values (+1, 0, -1), and has majority energy distributed on its (2(n))th primary harmonics. Tri-level MFM signals have both high energy efficiency and a low crest factor. An impedance measurement experiment excited by an 8th-order tri-level MFM signal on a RC three-element equivalent model has been performed, and the results on 8 primary harmonic frequencies ranging from 8 to 1024 kHz show a high accuracy with the mean amplitude relative error of 0.41% and mean phase absolute error of 0.18°, which has validated the feasibility of the tri-level MFM signals for broadband BIS measurement.
Department of Precision and Instrumentation Engineering, Xi'an University of Technology, Xi'an, People's Republic of China.
Yuxiang
Y
Yang
Lianhuan
L
Wang
Peipei
P
Wang
Xiufang
X
Yang
Fu
F
Zhang
He
H
Wen
Zhaosheng
Z
Teng
D058266:Dielectric Spectroscopy / Q000379:methods*; D005240:Feasibility Studies