Wikstrand J, Nilsson K, Wallentin I
Br Heart J. 1977 Sep;39(9):995-1005. doi: 10.1136/hrt.39.9.995.
A calibration unit and a capillary-damped pick-up, of funnel type, intended for apex cardiograms and other non-invasive cardiac pulse curves are presented. The physical properties of a recording system, suitable for non-invasive cardiac diagnostic techniques, are reviewed. In 4 identical recording units consisting of a funnel with and without capillary damping, connected via air transmission to a transducer, the overamplification in the underdamped systems varied between 2-4 and 4-3, and in the capillary-damped systems between 1-1 and 1-2. The capillary damping gave an approximately linear relation between phase shift and frequency in the high frequency range with a calculated delay of about 4ms. The low frequency time constant in the systems varied between 1-9 and 4-6 s, depending on the amplifier setting used, which for sine curves of frequency 0-5 and 2 Hz means an apparent prematurity for their maxima and minima varying between 53 and 1 ms, this being larger with lower frequency time constants and lower frequency curves.
介绍了一种用于心尖心动图和其他无创心脏脉搏曲线的校准单元和漏斗型毛细管阻尼传感器。回顾了适用于无创心脏诊断技术的记录系统的物理特性。在4个相同的记录单元中，由带有和不带有毛细管阻尼的漏斗组成，通过空气传输连接到一个换能器，欠阻尼系统中的过放大倍数在2 - 4和4 - 3之间变化，而在毛细管阻尼系统中在1 - 1和1 - 2之间变化。毛细管阻尼在高频范围内给出了相位偏移和频率之间近似线性的关系，计算得出的延迟约为4毫秒。系统中的低频时间常数在1 - 9和4 - 6秒之间变化，这取决于所使用的放大器设置，对于频率为0 - 5和2赫兹的正弦曲线，这意味着它们的最大值和最小值的明显提前量在53和1毫秒之间变化，低频时间常数越低和频率曲线越低，提前量越大。
