RESONANCE ACOUSTIC LEVEL METER Russian patent published in 2012 - IPC G01F23/28 

FIELD: physics.

SUBSTANCE: resonance acoustic level meter has a sounding pipe along the axis of which there is at least one diaphragm with a centre hole, an electroacoustic transducer and a microphone, fitted in the top part of the pipe. The level meter also has a phase-shift keyed signal generator connected to the input of the electroacoustic transducer, series-connected and connected to the microphone output - a preamplifier, an analogue-to-digital converter, a first Fourier transform unit, a logarithmation unit, a second Fourier transform unit, a cepstrum function maximum selection unit, a selection unit, as well as a liquid level calculating unit and an indicator connected in series. The level meter also has a unit for correcting the position of cepstrum function maxima, connected between the output of the selection unit and the input of the level calculating unit.

EFFECT: high accuracy of measuring the level of a liquid in its entire range of variation by reducing systematic error in determining the level of the liquid arising when sound speed changes along the gaseous cavity of the tube, owing to use of signals from two reflecting diaphragms near the liquid and correcting the position of the cepstral maximum from the reflecting diaphragm nearest to the liquid, taking into account the effect thereon of the cepstral maximum from the liquid.

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