Ultrasonic liquid level determination device comprises an instrument with a digital sampling frequency that is at least three times the sound frequency so that the sound velocity can be precisely determined from fixed reflectors

摘要

Method for determining the liquid height in a container uses ultrasonic time of flight measurements. Accordingly an ultrasonic transducer is aimed at the fluid surface and the time elapsed when the echo is detected is calculated. At least one fixed reflector is placed in the measurement path to enable determination of the sound velocity. The echo signal is sampled at a frequency which is at least three times that of the sound frequency so that the echo signals can be accurately assigned to either a reflector or the liquid surface.