FIELD: determination of level and amount of water in reservoirs of water supply systems. SUBSTANCE: ultrasonic level indicator has generator of probing signals, indication unit, first piezoelectric pickup in the form of radiating and receiving converters installed horizontally and uniaxially and provided with concentrators of ultrasonic oscillations, second piezoelectric pickup mounted in one case with first pickup with displacement relative to the latter by fixed distance along direction of change of controlled level, driving mechanism coupled to case of pickups by flexible element in the form of steel strip having longitudinal row of through holes and two light guides brought uniaxially to flexible element with provision of optical contact through holes. Inlet plane of one of light guides is brought to source of light flux and output plane of the other - to photoconverter connected via photosignal amplifier to indication unit. Driving mechanism is fitted with electric motor which shaft carries pulley for flexible element and unit to control its operation also connected to indication unit composed of three electron keys, logic OR gate, logic AND gate and reversible counter. EFFECT: simplified design, enhanced operational reliability. 3 dwg
