Özet:

Instrumentation and measurement have become a very important field in the developing industry. This development reveals requirements such as minimization of measurement errors. Accurate measurement of flow and consumption is a significant process to avoid wrong billing and entanglement for water utilities. This paper presents an ultrasonic Time-of-Flight (TOF) estimation algorithm evaluation for liquid or gas flow rate measurement applications for electronic smart meters. Transducers, as a piezoelectric material, are employed in flow measurement industry, and generate ultrasonic sound waves against pressure. Reciprocal located transducers in a flow medium are triggered to obtain ultrasonic sound waves in both flow direction. Due to the small distance between transducers and speed of sound in flow medium, TOF calculation becomes a challenging process. Equivalent circuit model of a transducer is implemented on MATLAB/Simulink environment numerically, and both upstream and downstream signals, which are the transit waves between transducers and named in order to triggering order, are obtained. Firstly, behavior of an excited transducer is evaluated on simulation environment, and a random signal, which simulates measurement noise, is employed to mimic the real-world conditions. Problem definitions and proposed algorithms given in the literature are investigated, and candidate TOF measurement algorithms are selected. Each method is implemented. Afterward, obtained transit waves are employed with the conventional method to compute TOF at each zero-crossing point. To improve the measurement performance, a cross-correlation based method is proposed for TOF estimation process, and results are compared to conventional method-based measurements. Possible future directions of the study are indicated.

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