多频生物电阻抗高精度模拟解调技术的研究

在多频生物电阻抗模拟解调技术中,针对正交解调中需要预先测量或定标参考信号的幅值,从而引入额外测量误差的问题,提出了基于3路模拟乘法器和低通滤波器的幅值和相位独立解调法。该方法采用2路正交输出求取相位,用1路单独求取幅值。其优点是不需要对参考信号的幅值进行精确测量或定标,只要满足正交解调中的参考信号在相同频率下幅值相等即可,在高精度、多频生物电阻抗测量中具有较好的应用前景。

High-accuracy analog demodulation technology for multi-frequency bioelectrical impedance

In the analog quadrature demodulation of multi-frequency bio-electrical impedance, the amplitude of the reference signal has to be measured or calibrated previously, which would introduce extra system errors to the measured signal. So a new method based on the 3rd channel analog multipliers and low pass filters is designed. The2nd channel multipliers as quadrature demodulators are applied to the demodulation of the phase of signal, and the other one is for the amplitude independently. Its advantage is that it only requires the amplitudes of the 2 quadrature reference signals are equal when at the same frequency, and their amplitudes have not to be measured or calibrated. The method proves effective in high-accuracy measurement of multi-frequency bioelectrical impedance.