DPSD算法在人体阻抗测量中的应用仿真

Application simulation of DPSD algorithm in human body impedance measurement

针对人体阻抗测量中,采样的电压、电流信号往往十分微弱,通常掺杂入复杂噪声的特点,提出了一种数字相敏检波(Digital Phase Sensitive Detection,DPSD)算法。该算法可以避免模拟滤波所带来的相移问题,同时在低信噪比条件下精确地提取出原信号的幅度和相位。根据电压、电流的幅度和相位可以进一步算出人体阻抗值,提高电压、电流幅度和相位的计算精度,有利于减小阻抗值的计算误差。为验证该算法的有效性,文中以电压信号为例,通过Matlab仿真,在信噪比为30 dB,频率分别为10 kHz、100 kHz的条件下,得到的相位误差小于0.1°,幅度误差小于0.005 mV。

In the human body impedance measurement,the voltage and current signals sampled are often very weak,usually mixed into the complex noise characteristics.A Digital Phase Sensitive Detection(DPSD)algorithm is proposed.This algorithm can avoid the phase shift caused by analog filtering and accurately extract the amplitude and phase of the original signal under the condition of low SNR.The human body impedance value can be further calculated according to the voltage and current amplitude and phase.Therefore,improving the calculation accuracy of voltage,current amplitude and phase is beneficial to reduce the calculation error of the impedance value.In order to verify the effectiveness of the algorithm,this article takes the voltage signal as an example,through Matlab simulation,when the signal⁃to⁃noise ratio is 30 dB,the frequency is 10 kHz,100 kHz respectively,the phase error is less than 0.1°,the amplitude error is less than 0.005 mV.