Modified Ultrasonic Liquid Level Transducer Using Wave Intensity as the Informative Parameter

The conventional ultrasonic liquid level measurement techniques are generally based on time of flight (TOF) measurement technique of reflected sound wave from liquid surface in a storage tank. In the present paper, a modified ultrasonic liquid level transducer is developed using the intensity of a 40 kHz ultrasonic pulsating echo signal reflected from the liquid surface as the sensing parameter. A simple transducer circuit converts this pulsating signal into a D.C. voltage signal which is taken as a measure of the intensity of the reflected pulses obtained from the ultrasonic receiver probe. The characteristic equation showing the relation between the transducer output voltage and liquid level is derived in the paper. A proto type unit is developed and tested experimentally to determine the static characteristic of the proposed ultrasonic level transducer. The experimental results are reported in the paper. A nonlinear static characteristic with very good repeatability is observed.