FIELD: physics.
SUBSTANCE: acoustic radiator 1 mounted perpendicular to the outer surface of the walls of a reservoir is used to excite simultaneously symmetric and antisymmetric zero-mode Lamb waves which propagate on the inner and outer surface of the walls of the reservoir. Acoustic oscillations of these waves are received by an acoustic receiver 2 which is identical to the radiator and is mounted at a certain distance from the radiator. The control zone, which is bounded by two extreme parallel positions of the level of the liquid, lies between the acoustic receiver 1 and the acoustic radiator 2, which lie outside this zone. The value of the ratio of energy characteristics of the received and emitted signals associated with the symmetric and antisymmetric zero-mode Lamb waves are uniquely linked to the position of the level of liquid 13, relative the line where the radiator and the emitter are mounted. The reference signal, with which the information signal is compared and from which the relative value is determined, is the signal of the symmetric zero-mode Lamb wave which arrives first and is located in the "clean" zone free from interference since that wave has the highest speed compared to the antisymmetric wave of the same mode. The apparatus has two acoustic transducers: a radiator 1 and a receiver 2, which include piezoelectric transducers 2, a receiving amplifier 6, a power amplifier 5, and a signal generating and conversion unit 7, which is in form of a microcontroller.
EFFECT: high reliability and accuracy of measuring the level of liquid in a reservoir.
5 cl, 2 dwg
