Buxi Dilpreet, Dugar Rahul, Redoute Jean-Michel, Yuce Mehmet Rasit
Annu Int Conf IEEE Eng Med Biol Soc. 2017 Jul;2017:693-696. doi: 10.1109/EMBC.2017.8036919.
This paper describes a continuous wave (CW) radar system with body-contact antennas and basic signal processing. The goal is to assess the signals' reproducibility across different subjects as well as a respiration cycle. Radar signals using body-contact antennas with a carrier frequency of 868 MHz are used to acquire the cardiac activity at the sternum. The radar I and Q channel signals are combined to form their magnitude. Signals are collected from six healthy males during paced breathing conditions. The electrocardiogram (ECG) and impedance cardiogram (ICG) signals are acquired simultaneously as reference. The chosen feature in the radar signal is the maximum of its second derivative, which is closest to the ICG B-point. The median and mean absolute errors in pre-ejection period (PEP) in milliseconds between the ICG's B-point and chosen feature in the radar signal range from -6-119.7 ms and 7.8-62.3 ms for all subjects. The results indicate that a reproducible radar signal is obtained from all six subjects. More work is needed on understanding the origin of the radar signals using ultrasound as a comparison.
本文描述了一种带有身体接触式天线和基本信号处理的连续波（CW）雷达系统。目标是评估信号在不同受试者以及一个呼吸周期内的可重复性。使用载波频率为868 MHz的身体接触式天线的雷达信号用于获取胸骨处的心脏活动。雷达的I和Q通道信号被组合以形成其幅度。在有节奏的呼吸条件下从六名健康男性收集信号。同时采集心电图（ECG）和阻抗心动图（ICG）信号作为参考。雷达信号中选择的特征是其最接近ICG B点的二阶导数的最大值。对于所有受试者，ICG的B点与雷达信号中所选特征之间的射血前期（PEP）的中位数和平均绝对误差（以毫秒为单位）范围为-6 - 119.7毫秒和7.8 - 62.3毫秒。结果表明从所有六名受试者都获得了可重复的雷达信号。需要开展更多工作，以超声作为比较来理解雷达信号的来源。
