Hamouda Assia, Manck Otto, Hafiane Mohamed Lamine, Bouguechal Nour-Eddine
Institut für Technische Informatik und Mikroelektronik, Technische Universität Berlin, Einsteinufer 17, Berlin 10587, Germany.
Laboratoire d'Electronique Avancée, Département d'Electronique, Université Batna 2, Rue Chahid Boukhlouf, Batna 05000, Algeria.
Sensors (Basel). 2016 Jun 29;16(7):1008. doi: 10.3390/s16071008.
This paper proposes a new, improved method for water flow metering. It applies to a transit time ultrasonic flow meter device. In principle, the flow of a given liquid in a pipe is obtained by measuring the transit times of an ultrasonic wave in the upstream and downstream directions. The difference between these times is, in theory, linearly proportional to the liquid flow velocity. However, the fainter the flow is, the smaller the transit time difference (TTD) is. This difference can be as low as a few picoseconds, which gives rise to many technical difficulties in measuring such a small time difference with a given accuracy. The proposed method relies on measuring the TTD indirectly by computing the phase difference between the steady-state parts of the received signals in the upstream and downstream directions and by using a least-square-sine-fitting technique. This reduces the effect of the jitter noise and the offset, which limit measurement precision at very low flow velocity. The obtained measurement results illustrate the robustness of the proposed method, as we measure the TTD at no-flow conditions, with a precision as low as 10 ps peak-to-peak and a TTD offset of zero, within a temperature range from room temperature to 80 °C. This allows us to reach a smaller minimum detectable flow when compared with previous techniques. The proposed method exhibits a better trade-off between measurement accuracy and system complexity. It can be completely integrated in an ASIC (application specific integrated circuit) or incorporated in a CPU- or micro-controller-based system.
本文提出了一种新的、改进的水流计量方法。它适用于渡越时间超声流量计装置。原则上，通过测量超声波在管道中上游和下游方向的渡越时间来获取给定液体在管道中的流量。理论上，这些时间之间的差值与液体流速成线性比例。然而，流量越微弱，渡越时间差（TTD）就越小。这个差值可能低至几皮秒，这在以给定精度测量如此小的时间差时会引发许多技术难题。所提出的方法依靠通过计算上游和下游方向接收信号稳态部分之间的相位差并使用最小二乘正弦拟合技术来间接测量TTD。这减少了抖动噪声和偏移的影响，而这些在极低流速下会限制测量精度。所获得的测量结果说明了所提方法的稳健性，因为我们在无流量条件下测量TTD，在室温至80°C的温度范围内，精度低至峰峰值10皮秒且TTD偏移为零。与先前技术相比，这使我们能够达到更小的最小可检测流量。所提方法在测量精度和系统复杂性之间展现出更好的权衡。它可以完全集成在专用集成电路（ASIC）中，或并入基于CPU或微控制器的系统中。
