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Method of measuring the propagation time of a sound signal in a fluid by means of a zero-crossing of said sound signal
Method of measuring the propagation time of a sound signal in a fluid by means of a zero-crossing of said sound signal
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机译:通过所述声音信号的零交叉来测量声音信号在流体中的传播时间的方法
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摘要
Measuring the propagation time of a sound signal between two spaced-apart transducers disposed in a fluid flow involves determining the zero-crossing of the signal. Each received sound signal is sampled and digitized, then for each period of the sampled and digitized signal the maximum amplitudes P− and P+ of the two lobes of the period under examination are determined. The ratio of the amplitudes are compared to an ideal amplitude ratio between the maximum amplitudes Pi− and Pi+ of two lobes of a first ideal characteristic period. The first zero-crossing of the characteristic oscillations of the signal is determined. And, as a function of the result of the comparison relative to a threshold value Gs, the period under examination is accepted or ignored as a characteristic period. The zero-crossing thereof is determined or not determined between the two lobes of the characteristic period.
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